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Recombinant sequences of the SARS-CoV-2 Omicron variant were detected in surveillance samples collected in north-western Finland in January 2022. We detected 191 samples with an identical genome arrangement in weeks 3 to 11, indicating sustained community transmission. The recombinant lineage has a 5’-end of BA.1, a recombination breakpoint between orf1a and orf1b (nucleotide position 13,296–15,240) and a 3’-end of BA.2 including the S gene. We describe the available genomic and epidemiological data about this currently circulating recombinant XJ lineage.

ObjectiveWe compared the clinical characteristics, findings and outcomes of hospitalized patients with coronavirus disease 2019 (COVID-19) or influenza to detect relevant differences.MethodsFrom December 2019 to April 2020, we recruited all eligible hospitalized adults with respiratory infection to a prospective observational study at the HUS Jorvi Hospital, Finland. Influenza and SARS-CoV-2 infections were confirmed by RT-PCR. Follow-up lasted for at least 30 days from admission.ResultsWe included 61 patients, of whom 28 were COVID-19 and 33 influenza patients with median ages of 53 and 56 years. Majority of both COVID-19 and influenza patients were men (61% vs 67%) and had at least one comorbidity (68% vs 85%). Pulmonary diseases and current smoking were less common among COVID-19 than influenza patients (5 [18%] vs 15 [45%], P=0.03 and 1 [4%] vs 10 [30%], P=0.008). In chest x-ray at admission, ground-glass opacities and consolidations were more frequent among COVID-19 than influenza patients (19 [68%] and 7 [21%], P < 0.001). Severe disease and intensive care unit (ICU) admission occurred more often among COVID-19 than influenza patients (26 [93%] vs 19 [58%], P=0.003 and 8 [29%] vs 2 [6%], P=0.034). COVID-19 patients were hospitalized longer than influenza patients (6 days [IQR 4-21] vs 3 [2-4], PConclusionBilateral ground-glass opacities and consolidations in chest X-ray may help to differentiate COVID-19 from influenza. Hospitalized COVID-19 patients had more severe disease, required longer hospitalization and were admitted to ICU more often than influenza patients, which has important implications for public health policies.

Multiple introductions of SARS-COV-2 Omicron variant BA.1. and BA.1.1. lineages to Finland were detected early December 2021, and comprised the majority over Delta variant in 3 weeks in the capital region. Our sequence analysis demonstrates emergence of a large cluster of BA.1.1 in community transmission.

Novel SARS coronavirus causing COVID-19 was recognized in late 2019. Diagnostics was quickly ramped up worldwide based on the detection of viral RNA. Based on the scientific knowledge for pre-existing coronaviruses, it was expected that the RNA of this novel coronavirus will be detected at significant rates from symptomatic and asymptomatic individuals due to existence of non-infectious RNA. To increase the efficacy of diagnostics, surveillance, screening and pandemic control, rapid methods, such as antigen tests, are needed for decentralized testing and to assess infectiousness. The objectives were to verify analytical sensitivity and specificity, and assess the clinical sensitivity, specificity and usability of a novel automated mariPOC SARS-CoV-2 test based on sophisticated optical laser technology detecting viral structure proteins. Analytical performance was verified using bacterial and viral preparations. Clinical performance of the test was evaluated against qRT-PCR in a retrospective study with nasopharyngeal swab specimens (N=211) collected from symptomatic patients suspected of acute SARS-CoV-2 infections. Sensitivity and specificity of the mariPOC test were 92.3% (12/13) and 100.0% (198/198), respectively. The test’s limit of detection was 22 PFU/test and it had no cross-reactions with the tested respiratory microbes. Our study shows that the mariPOC can detect infectious individuals already in 20 minutes while clinical sensitivity close to qRT-PCR is achieved in two hours or less. The test targets conserved epitopes of SARS-CoV-2 nucleoprotein, making it robust against strain variations. The new test is a promising and versatile tool for syndromic testing of symptomatic cases and for high capacity infection control screening.

The gold standard for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection diagnosis is reverse transcription (RT)-PCR from a nasopharyngeal swab specimen (NPS). Its collection involves close contact between patients and health care workers, requiring a significant amount of workforce and putting them at risk of infection. We evaluated self-collection of alternative specimens and compared their sensitivity and cycle threshold (CT) values to those of NPS. We visited acute coronavirus disease 2019 (COVID-19) outpatients to collect concomitant NPS and gargle specimens and had patients self-collect gargle and either sputum or spit specimens the next morning. We included 40 patients and collected 40 concomitant NPS and gargle specimens, as well as 40 gargle, 22 spit, and 16 sputum specimens the next day (2 patients could not produce sputum). All specimens were as sensitive as NPS. Gargle specimens had a sensitivity of 0.97 (95% confidence interval [CI], 0.92 to 1.00), whether collected concomitantly with NPS or the next morning. Next-morning spit and sputum specimens showed sensitivities of 1.00 (95% CI, 1.00 to 1.00) and 0.94 (95% CI, 0.87 to 1.00]), respectively. The gargle specimens had significantly higher mean CT values of 29.89 (standard deviation [SD], 4.63; P < 0.001) and 29.25 (SD, 3.99; P < 0.001) when collected concomitantly and the next morning, respectively, compared to NPS (22.07 [SD, 4.63]). CT values obtained with spit (23.51 [SD, 4.57]; P = 0.11) and sputum (25.82 [SD, 9.21]; P = 0.28) specimens were close to those of NPS. All alternative specimen collection methods were as sensitive as NPS, but spit collection appeared more promising, with a low CT value and ease of collection. Our findings warrant further investigation. IMPORTANCE Control of the COVID-19 pandemic relies heavily on a test-trace-isolate strategy. The most commonly used specimen for diagnosis of SARS-CoV-2 infection is a nasopharyngeal swab. However, this method is quite uncomfortable for the patient, requires specific equipment (nose swabs and containers), and requires close proximity to health care workers, putting them at risk of infection. Developing alternative sampling strategies could decrease the burden for health care workers, help overcome potential shortages of equipment, and improve acceptability of testing by reducing patient discomfort. publishedVersion

An outbreak caused by the SARS-CoV-2 Delta variant (B.1.617.2) spread from one inpatient in a secondary care hospital to three primary care facilities, resulting in 58 infections including 18 deaths in patients and 45 infections in healthcare workers (HCW). Only one of the deceased cases was fully vaccinated. Transmission occurred despite the use of personal protective equipment by the HCW, as advised in national guidelines, and a high two-dose COVID-19 vaccination coverage among permanent staff members in the COVID-19 cohort ward. publishedVersion

Two SARS-CoV-2 Variants of Concern, Alpha (~ 80%) and Beta (~ 23%) rapidly became dominant in Finland in the spring of 2021 but diminished near summer. To assess their temporal epidemiological dynamics among Finnish cases, we began large-scale sequencing efforts to identify spreading events and sources via phylogenetic clustering analyses. The results show the majority belonged to clusters spreading in the community while few sequenced samples were singletons. The results highlight the importance of surveillance and preventative policies in controlling the epidemic.

SummaryBackgroundHousehold transmission studies offer the opportunity to assess both secondary attack rate and persistence of SARS-CoV-2 antibodies over time.MethodsWe invited confirmed COVID-19 cases and their household members to attend up to four household visits with collection of nasopharyngeal and serum samples over 28 days after index case onset. We calculated secondary attack rates (SAR) based on the presence of SARS-CoV-2 nucleoprotein IgG antibodies (IgG Ab) and/or neutralizing antibodies (NAb) overall and per households. Three and six months later, we assessed the persistence of SARS-CoV-2 antibodies.FindingsWe recruited 39 index cases and 90 household members. Among 87 household members evaluated, SAR was 48% (n=42), including 37 symptomatic secondary cases. In total, 80/129 (62%) participants developed both IgG Ab and NAb, while three participants only developed IgG Ab. Among participants who had both IgG Ab and NAb during the initial follow-up, 68/69 (99%) and 63/70 (90%) had IgG Ab and NAb at 3 months, while at 6 months, 59/75 (79%) and 63/75 (84%) had IgG Ab and NAb, respectively. Participants who required hospital care had initially 5-fold IgG Ab concentrations compared to cases with mild symptoms and 8-fold compared to asymptomatic cases.InterpretationFollowing detection of a COVID-19 case in a household, other members had a high risk of becoming infected. Follow-up of participants showed strong persistence of antibodies in most cases.FundingThis study was supported by THL coordinated funding for COVID-19 research (Finnish Government’s supplementary budget) and by the Academy of Finland (Decision number 336431).Research in contextEvidence before this studyHousehold transmission studies are pivotal to the characterization of transmission dynamics of emerging infectious diseases in a closed setting with homogenous exposure, including proportion of asymptomatic cases using serologic assessment of infection. Additionally, data on long-term persistence of immune response, including neutralizing antibodies following COVID-19 remains scarce. Our search on PubMed for articles published between January 1st 2020, and June 1st, 2021 using the search terms “household” AND “transmission” AND (“COVID-19” OR “SARS-CoV-2”) retrieved 381 results including 35 relevant articles: 21 original household transmission studies, 5 reviews and 9 statistical transmission, modelling or register linkage studies. Depending on the diagnosis method and the duration of follow-up, secondary attack rates (SAR) ranged from 4.6% when household contacts were followed for 14 days and tested only in case of symptoms to close to 90%. None of the household transmission studies involved long-term convalescent follow-up.Added value of this studyThis extensive (one month) active follow-up, using RT-PCR diagnosis and serological testing for SARS-CoV-2 nucleoprotein IgG antibodies (IgG Ab) and neutralizing antibodies (NAb) showed that household transmission was high, with a 48% (42/87) SAR overall and 50% [IQR: 0-100%] at the level of the household. All but one out of 64 RT-PCR confirmed participants had developed both IgG Ab and NAb after immediate convalescence. Six months after inclusion, majority of previously seropositive (IgG and/or NAb) participants still had IgG Ab (59/75) or NAb (63/75) showing long-term persistence of humoral immunity to SARS-CoV-2.Implications of all the available evidenceThe risk of transmission of SARS-CoV-2 infections within households is considerable. Isolation of the primary case, especially from household contacts with a high risk of severe disease, e.g. due to age or comorbidities, should be considered even though viral shedding might occur before confirmed diagnosis in household contacts. Long-term persistence of antibodies following infection, even in asymptomatic and mild cases, suggests enduring natural immunity and possibly protection from severe COVID-19.

Publisher Copyright: © 2021 Background shared accommodation may increase the risk of SARS-CoV-2 transmission. In April 2020, an increasing number of asylum seekers at a reception centre in Espoo, Finland presented with COVID-19 despite earlier implementation of preventive measures. We decided to screen the entire population of the centre for SARS-CoV-2. Methods we offered nasopharyngeal swab collection and SARS-CoV-2 real-time polymerase chain reaction (RT-PCR) analysis to the centre's clients. Symptoms were recorded at the time of diagnostic sample collection using electronic forms and followed up for two weeks through phone interviews and a review of medical records. Findings 260 clients were screened. Of them, 96 (37%) were found positive for SARS-CoV-2 and isolated. The high attack rate prompted the local public health authority to set the other clients in quarantine for 14 days to prevent further spread. Of the positive cases, 61 (64%) reported having had symptoms at the time of the screening or one week prior. Of the 35 initially asymptomatic individuals, 12 developed symptoms during follow-up, while 23 (or 18% of all screened SARS-CoV-2 positive clients) remained asymptomatic. No widespread transmission of COVID-19 was detected after the quarantine was lifted. Interpretation in this large COVID-19 outbreak, voluntary mass screening provided valuable information about its extent and helped guide the public health response. Comprehensive quarantine and isolation measures were likely instrumental in containing the outbreak. Funding Finnish Institution for Health and Welfare, Finnish Immigration Agency, City of Espoo

SummaryBackgroundThe role of children in SARS-CoV-2 transmission is unclear. We investigated two COVID-19 school exposure incidents in the Helsinki area.MethodsWe conducted two retrospective cohort studies after schools exposures, with a household transmission extension. We defined a case as an exposed person with either a positive RT-PCR, or positive microneutralisation testing (MNT) as confirmation of SARS-CoV-2 nucleoprotein IgG antibodies detection via fluorescent microsphere immunoassay (FMIA). We recruited close school contacts and families of school cases, calculated attack rates (AR) on school level and families, and identified transmission chains.FindingsIn incident A, the index was a pupil. Participation rate was 74% (89/121), and no cases were identified. In incident B, the index was a member of school personnel. Participation rate was 81% (51/63). AR was 16% (8/51): 6 pupils and 1 member of school personnel were MNT and FMIA positive; 1 pupil had a positive RT-PCR, but negative serology samples. We visited all school cases’ families (n=8). The AR among close household contacts was 42% (9/20 in 3/8 families) but other plausible sources were always reported. At three months post-exposure, 6/8 school cases were re-sampled and still MNT positive.InterpretationWhen the index was a child, no school transmission was identified, while the occurrence of an adult case led to a 16% AR. Further cases were evidenced in 3 families, but other transmission chains were plausible. It is likely that transmission from children to adults is limited.FundingThe Finnish Institute for Health and Welfare funded this study.Research in contextEvidence before the studyThe first autochthonous case of COVID-19 in Finland was identified on February 29th. Transmission of the virus has led to more than 7250 cases and over 300 deaths (As of July 12th 2020). On March 16th, assuming that children might have a role in transmission, the Finnish government ordered school closures, to the exclusion of pre-school and grades 1-3. Schools were closed from March 18 and reopened on May 14th. At the stage of closure, a very limited number of reports of school related COVID-19 clusters or exposure incidents had been published, and the potential extent of transmission in a school setting was unknown.Added value of this studyWe investigated two exposure incidents in two different schools from the Helsinki area to assess transmission among pupils, school personnel and household contacts of identified cases. In school A, contact with a COVID-19 pupil did not lead to further transmission, while in school B, out of 51 recruited contacts, eight (16%) were proved to have had COVID-19 infection, including one member of staff. Among the close household contacts of pupils who were tested positive, COVID-19 attack rate was 31% (5/16). However, in all investigated households, other sources of infections were plausible; hence household transmission following a pediatric COVID-19 case appears to be limited.Implications of all of the available evidenceIncidence of COVID-19 infections in children following school related exposure was limited, as well as secondary transmission within their household. We hope our findings will help prioritize mitigation measures as well as reduce worry among parents of school aged children as most EU countries are preparing for the start of a new school year in autumn.

Background Avian influenza A(H5N1) viruses have caused sporadic infections in humans and thus they pose a significant global health threat. Among symptomatic patients the case fatality rate has been ca. 50%. H5N1 viruses exist in multiple clades and subclades and several candidate vaccines have been developed to prevent A(H5N1) infection as a principal measure for preventing the disease. Methods Serum antibodies against various influenza A(H5N1) clade viruses were measured in adults by ELISA-based microneutralization and haemagglutination inhibition tests before and after vaccination with two different A(H5N1) vaccines in 2009 and 2011. Results Two doses of AS03-adjuvanted A/Indonesia/5/2005 vaccine induced good homologous but poor heterologous neutralizing antibody responses against different clade viruses. However, non-adjuvanted A/Vietnam/1203/2004 booster vaccination in 2011 induced very strong and long-lasting homologous and heterologous antibody responses while homologous response remained weak in naive subjects. Conclusions Sequential vaccination with two different A(H5N1) pre-pandemic vaccines induced long-lasting high level cross-clade immunity against influenza A(H5N1) strains, thus supporting a prime-boost vaccination strategy in pandemic preparedness plans.

Influenza A(H3N2), A(H1N1)pdm09 and B viruses co-circulated in Europe in 2017-18, predominated by influenza B. WHO-recommended, trivalent vaccine components were lineage-mismatched for B. The I-MOVE hospital network measured 2017-18 seasonal influenza vaccine effectiveness (IVE) against influenza A(H3N2) and B among hospitalised patients (≥65 years) in Europe. Following the same generic protocol for test-negative design, hospital teams in nine countries swabbed patients ≥65 years with recent onset (≤7 days) severe acute respiratory infection (SARI), collecting information on demographics, vaccination status and underlying conditions. Cases were RT-PCR positive for influenza A(H3N2) or B; controls: negative for any influenza. "Vaccinated" patients had SARI onset >14 days after vaccination. We measured pooled IVE against influenza, adjusted for study site, age, sex, onset date and chronic conditions. We included 3483 patients: 376 influenza A(H3N2) and 928 B cases, and 2028 controls. Most (>99%) vaccinated patients received the B lineage-mismatched trivalent vaccine. IVE against influenza A(H3N2) was 24% (95% CI: 2 to 40); 35% (95% CI: 6 to 55) in 65- to 79-year-olds and 14% (95% CI: -22 to 39) in ≥80-year-olds. Against influenza B, IVE was 30% (95% CI: 16 to 41); 37% (95% CI: 19 to 51) in 65- to 79-year-olds and 19% (95% CI: -7 to 38) in ≥80-year-olds. IVE against influenza B was similar to A(H3N2) in hospitalised older adults, despite trivalent vaccine and circulating B lineage mismatch, suggesting some cross-protection. IVE was lower in those ≥80 than 65-79 years. We reinforce the importance of influenza vaccination in older adults as, even with a poorly matched vaccine, it still protects one in three to four of this population from severe influenza. This study received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No. 634446. The I‐MOVE study team is very grateful to all patients, hospital teams, laboratory teams and regional epidemiologists who have contributed to the studies. Sí

The first case of coronavirus disease (COVID-19) in Finland was confirmed on 29 January 2020. No secondary cases were detected. We describe the clinical picture and laboratory findings 3–23 days since the first symptoms. The SARS-CoV-2/Finland/1/2020 virus strain was isolated, the genome showing a single nucleotide substitution to the reference strain from Wuhan. Neutralising antibody response appeared within 9 days along with specific IgM and IgG response, targeting particularly nucleocapsid and spike proteins.

Human coronaviruses (CoVs) are increasingly recognized as important respiratory pathogens associated with a broad range of clinical diseases. We sought to increase the insight into clinically relevant CoV infections by monitoring antigen concentrations in six confirmed CoV-positive patients using a newly developed assay for rapid detection of CoV OC43 infections. Antigen positivity lasted 3 to 6 days in secondary infections and 13 days in primary infection. CoV infections are clinically diverse, are common, and cannot be diagnosed from clinical symptoms alone. Keywords: Human coronavirus, point-of-care test, rapid antigen test, rapid detection, respiratory tract infection

Background Morbidity, severity, and mortality associated with annual influenza epidemics are of public health concern. We analyzed surveillance data on hospitalized laboratory-confirmed influenza cases admitted to intensive care units to identify common determinants for fatal outcome and inform and target public health prevention strategies, including risk communication. Methods We performed a descriptive analysis and used Poisson regression models with robust variance to estimate the association of age, sex, virus (sub)type, and underlying medical condition with fatal outcome using European Union data from 2009 to 2017. Results Of 13 368 cases included in the basic dataset, 2806 (21%) were fatal. Age ≥40 years and infection with influenza A virus were associated with fatal outcome. Of 5886 cases with known underlying medical conditions and virus A subtype included in a more detailed analysis, 1349 (23%) were fatal. Influenza virus A(H1N1)pdm09 or A(H3N2) infection, age ≥60 years, cancer, human immunodeficiency virus infection and/or other immune deficiency, and heart, kidney, and liver disease were associated with fatal outcome; the risk of death was lower for patients with chronic lung disease and for pregnant women. Conclusions This study re-emphasises the importance of preventing influenza in the elderly and tailoring strategies to risk groups with underlying medical conditions.

Influenza A(H1N1)pdm09 viruses have been circulating throughout the world since the 2009 pandemic. A/California/07/2009 (H1N1) virus was included in seasonal influenza vaccines for seven years altogether, providing a great opportunity to analyse vaccine-induced immunity in relation to the postpandemic evolution of the A(H1N1)pdm09 virus. Serum antibodies against various epidemic strains of influenza A (H1N1)pdm09 viruses were measured among health care workers (HCWs) by haemagglutination inhibition and microneutralization tests before and after 2010 and 2012 seasonal influenza vaccinations. We detected high responses of vaccine-induced neutralizing antibodies to six distinct genetic groups. Our results indicate antigenic similarity between vaccine and circulating A(H1N1)pdm09 strains, and substantial vaccine-induced immunity against circulating epidemic viruses. (C) 2019 Published by Elsevier Ltd.

BACKGROUND Influenza B virus strains in trivalent influenza vaccines are frequently mismatched to the circulating B strains, but the population-level impact of such mismatches is unknown. We assessed the impact of vaccine mismatch on the epidemiology of influenza B during 12 recent seasonal outbreaks of influenza in Finland. METHODS We analyzed all available nationwide data on virologically confirmed influenza infections in all age groups in Finland between 1 July 1999 and 30 June 2012, with the exclusion of the pandemic season of 2009-2010. We derived data on influenza infections and the circulation of different lineages of B viruses during each season from the Infectious Diseases Register and the National Influenza Center, National Institute for Health and Welfare, Finland. RESULTS A total of 34 788 cases of influenza were recorded. Influenza A accounted for 74.0% and influenza B for 26.0% of all typed viruses. Throughout the 12 seasons, we estimated that 41.7% (3750 of 8993) of all influenza B infections were caused by viruses representing the other genetic lineage than the one in the vaccine. Altogether, opposite-lineage influenza B viruses accounted for 10.8% of all influenza infections in the population, the proportion being highest (16.8%) in children aged 10-14 years and lowest (2.6%) in persons aged ≥70 years. CONCLUSIONS The population-level impact of lineage-level mismatch between the vaccine and circulating strains of influenza B viruses is substantial, especially among children and adolescents. The results provide strong support for the inclusion of both influenza B lineages in seasonal influenza vaccines.

The publisher regrets that the co-authors in the “European region influenza surveillance network” were not tagged correctly. The full and complete list of authors and their affiliations for this article is given above. The publisher would like to apologise for any inconvenience caused.

International audience; BACKGROUND: The global impact of the 2009 influenza A(H1N1) pandemic (H1N1pdm) is not well understood. OBJECTIVES: We estimate overall and age-specific prevalence of cross-reactive antibodies to H1N1pdm virus and rates of H1N1pdm infection during the first year of the pandemic using data from published and unpublished H1N1pdm seroepidemiological studies.METHODS: Primary aggregate H1N1pdm serologic data from each study were stratified in standardized age groups and evaluated based on when sera were collected in relation to national or subnational peak H1N1pdm activity. Seropositivity was assessed using well-described and standardized hemagglutination inhibition (HI titers ≥ 32 or ≥ 40) and microneutralization (MN ≥ 40) laboratory assays. The prevalence of cross-reactive antibodies to the H1N1pdm virus was estimated for studies using sera collected prior to the start of the pandemic (between 2004 and April 2009); H1N1pdm cumulative incidence was estimated for studies in which collected both pre- and post-pandemic sera; and H1N1pdm seropositivity was calculated from studies with post-pandemic sera only (collected between December 2009-June 2010).RESULTS: Data from 27 published/unpublished studies from 19 countries/administrative regions - Australia, Canada, China, Finland, France, Germany, Hong Kong SAR, India, Iran, Italy, Japan, Netherlands, New Zealand, Norway, Reunion Island, Singapore, United Kingdom, United States, and Vietnam - were eligible for inclusion. The overall age-standardized pre-pandemic prevalence of cross-reactive antibodies was 5% (95%CI 3-7%) and varied significantly by age with the highest rates among persons ≥ 65 years old (14% 95%CI 8-24%). Overall age-standardized H1N1pdm cumulative incidence was 24% (95%CI 20-27%) and varied significantly by age with the highest in children 5-19 (47% 95%CI 39-55%) and 0-4 years old (36% 95%CI 30-43%).CONCLUSIONS: Our results offer unique insight into the global impact of the H1N1 pandemic and highlight the need for standardization of seroepidemiological studies and for their inclusion in pre-pandemic preparedness plans. Our results taken together with recent global pandemic respiratory-associated mortality estimates suggest that the case fatality ratio of the pandemic virus was approximately 0.02%.

Although widely recommended, influenza vaccination of children is part of the national vaccination programme only in few countries. In addition to Canada and the United States (US), in Europe Finland and the United Kingdom have introduced live attenuated influenza vaccine (LAIV) for healthy children in their programmes. On 22 June 2016, the US Advisory Committee on Immunizations Practices, voted against further use of LAIV due to no observed vaccine effectiveness (VE) over three consecutive influenza seasons (2013/14 to 2015/16). We summarise the results of a nationwide, register-based cohort study (N=55,258 of whom 8,086 received LAIV and 4,297 TIV); all outcome (laboratory-confirmed influenza), exposure (vaccination) and confounding variable data were retrieved from four computerised national health registers, which were linked via a unique personal identity code assigned to all permanent Finnish residents regardless of nationality. Our study provides evidence of moderate effectiveness against any laboratory-confirmed influenza of the quadrivalent LAIV vaccine (VE: 51%; 95% confidence interval (CI): 28–66%) as well as the inactivated trivalent vaccine (VE: 61%; 95% CI: 31–78%) among two-year-olds during the influenza season 2015/16 in Finland. Based on these data, Finland will continue using LAIV for young children in its National Immunisation Programme this coming influenza season.

Members of the World Health Organization European Region and European Influenza Surveillance Network of the reporting countries - Portugal: Raquel Guiomar, Pedro Pechirra, Paula Cristovão, Inês Costa, Patrícia Conde, Baltazar Nunes, Ana Rodrigues Influenza A(H1N1)pdm09 viruses predominated in the European influenza 2015/16 season. Most analysed viruses clustered in a new genetic subclade 6B.1, antigenically similar to the northern hemisphere vaccine component A/California/7/2009. The predominant influenza B lineage was Victoria compared with Yamagata in the previous season. It remains to be evaluated at the end of the season if these changes affected the effectiveness of the vaccine for the 2015/16 season. info:eu-repo/semantics/publishedVersion

Influenza antigenic and genetic characterisation data are crucial for influenza vaccine composition decision making. Previously, aggregate data were reported to the European Centre for Disease Prevention and Control by European Union/European Economic Area (EU/EEA) countries. A system for collecting case-specific influenza antigenic and genetic characterisation data was established for the 2013/14 influenza season. In a pilot study, 11 EU/EEA countries reported through the new mechanism. We demonstrated feasibility of reporting strain-based antigenic and genetic data and ca 10% of influenza virus-positive specimens were selected for further characterisation. Proportions of characterised virus (sub)types were similar to influenza virus circulation levels. The main genetic clades were represented by A/StPetersburg/27/2011(H1N1)pdm09 and A/Texas/50/2012(H3N2). A(H1N1)pdm09 viruses were more prevalent in age groups (by years)

Background Influenza A(H1N1)pdm09 virus has been circulating in human population for three epidemic seasons. During this time, monovalent pandemic and trivalent seasonal influenza vaccination against this virus have been offered to Finnish healthcare professionals. It is, however, unclear how well vaccine-induced antibodies recognize different strains of influenza A(H1N1)pdm09 circulating in the population and whether the booster vaccination with seasonal influenza vaccine would broaden the antibody cross-reactivity. Objectives Influenza vaccine-induced humoral immunity against several isolates of influenza A(H1N1)pdm09 virus was analyzed in healthcare professionals. Age-dependent responses were also analyzed. Methods Influenza viruses were selected to represent viruses that circulated in Finland during two consecutive influenza epidemic seasons 2009–2010 and 2010–2011. Serum samples from vaccinated volunteers, age 20–64 years, were collected before and after vaccination with AS03-adjuvanted pandemic and non-adjuvanted trivalent seasonal influenza vaccine that was given 1 year later. Results Single dose of pandemic vaccine induced a good albeit variable antibody response. On day 21 after vaccination, depending on the virus strain, 14–75% of vaccinated had reached antibody titers (≥1:40) considered seroprotective. The booster vaccination 1 year later with a seasonal vaccine elevated the seroprotection rate to 57–98%. After primary immunization, younger individuals (20–48 years) had significantly higher antibody titers against all tested viruses than older persons (49–64 years) but this difference disappeared after the seasonal booster vaccination. Conclusions Even a few amino acid changes in influenza A HA may compromise the vaccine-induced antibody recognition. Older adults (49 years and older) may benefit more from repeated influenza vaccinations.

Influenza A virus nonstructural protein 1 (NS1A protein) is a virulence factor which is targeted into the nucleus. It is a multifunctional protein that inhibits host cell pre-mRNA processing and counteracts host cell antiviral responses. We show that the NS1A protein can interact with all six human importin α isoforms, indicating that the nuclear translocation of NS1A protein is mediated by the classical importin α/β pathway. The NS1A protein of the H1N1 (WSN/33) virus has only one N-terminal arginine- or lysine-rich nuclear localization signal (NLS1), whereas the NS1A protein of the H3N2 subtype (Udorn/72) virus also has a second C-terminal NLS (NLS2). NLS1 is mapped to residues 35 to 41, which also function in the double-stranded RNA-binding activity of the NS1A protein. NLS2 was created by a 7-amino-acid C-terminal extension (residues 231 to 237) that became prevalent among human influenza A virus types isolated between the years 1950 to 1987. NLS2 includes basic amino acids at positions 219, 220, 224, 229, 231, and 232. Surprisingly, NLS2 also forms a functional nucleolar localization signal NoLS, a function that was retained in H3N2 type virus NS1A proteins even without the C-terminal extension. It is likely that the evolutionarily well-conserved nucleolar targeting function of NS1A protein plays a role in the pathogenesis of influenza A virus.

Here, we report 40 new whole-genome sequences of influenza A(H1N1)pdm09 viruses isolated from Finnish patients during 2009 to 2014. A preliminary analysis of these and 186 other whole genomes of influenza A(H1N1)pdm09 viruses isolated from hospitalized and nonhospitalized patients during 2009 to 2014 in Finland revealed several viral mutations that might be associated with patient hospitalizations.

Virus strains in the seasonal influenza vaccine for the 2014/15 northern hemisphere season remained unchanged from those in 2013/14. During spring 2014, drifted influenza A(H3N2) viruses, subgroup 3C.3a, were detected in Finland; another subgroup, 3C.2a, emerged in the 2014/15 season and has predominated. We monitored antibody responses against vaccine and epidemic strains (2013/14 and 2014/15) among Finnish healthcare workers after influenza vaccination with the 2013/14 vaccine. The data suggest reduced cross-protection towards both subgroups of drifted A(H3N2) viruses.

Here, we report 40 complete genome sequences of influenza A/H1N1 strains isolated from 33 nonhospitalized and 7 hospitalized patients during the 2013-2014 epidemic season in Finland. An analysis of the aligned sequences revealed no oseltamivir-resistant genotypes. As a whole, the recent viruses have drifted from the prototype A/California/7/2009 virus by ca. 1.3%.

A new B/Shangdong/7/97-like influenza virus (Victoria/2/87 lineage) predominated during the 2002/2003 epidemic season in Finland and was estimated to account for 2246 of the 13496 feverish upper respiratory tract infections (URIs) occurring among conscripts in the Finnish army. The incidence (1716/10000 conscripts) was indicative of moderate epidemic activity at most. Analysis of the cross-reactive antibodies induced in 1988 suggests that the basis of the protection was probably established during the childhood of the conscripts. Vaccination in autumn 2002 prevented 42% of the URIs during the influenza B outbreak and 71% (95% CI 42–85) of infections interpreted as influenza B. Despite the low genetic variability of the Shangdong/7/97-like viruses, breakages of a potential glycosylation site in haemagglutinin (HA1, position 197) were frequent; their biological significance is discussed. The Shangdong/7/97-like strains were HA1/NA reassortants, as were also the less abundant strains that for HA1 belonged to the B/Yamagata/16/88 lineage. A further reassortment, which probably emerged during the outbreak in one of the garrisons, supports our hypothesis that circumstances in these settings may especially favour the emergence of diversity by reassortment.

A total of 102,600 upper respiratory infections (URI) were recorded among young military conscripts in the Finnish Defence Forces during the study period from October 1991 to March 1994. This period covered three outbreaks caused by H3N2-subtype influenza A virus and one outbreak of influenza B. During the 1991/92 outbreak caused by A/Beijing/353/89-like virus, the calculated influenza A incidence was 2,206/10,000 men. During the 1992/93 outbreak when influenza B was the predominant virus, a new drift variant of influenza A that belonged to the lineage of A/Beijing/32/92-like and A/Shangdong/9/93-like viruses circulated but the incidence of influenza A was not more than 1,044/10,000. A higher incidence, 2,810/10,000, was recorded during the 1993/94 outbreak, when the circulating virus was similar to the 1992/93 virus antigenically and with regard to haemagglutinin and neuraminidase (NA) gene sequences. Crossreactive haemagglutination-inhibition antibodies induced in 1991/92 probably were sufficient to restrict the epidemic activity in 1992/93 but no longer in 1993/94. Furthermore, during the 1991/92 outbreak, some of the A/Beijing/353/89-like viruses already had shared the NA sequence markers characteristic of the viruses in 1992/93 and 1993/94, which may also have strengthened protection in 1992/93.

Real-time reverse transcription-PCR assays specific for the nonstructural (NS) and hemagglutinin (HA) genes of the 2009 pandemic influenza A (H1N1) virus were developed and evaluated with clinical samples from infected patients. The tests are characterized by high sensitivity and specificity and performed well throughout the first year of the 2009 pandemic.

The influenza pH1N1 virus caused a global flu pandemic in 2009 and continues manifestation as a seasonal virus. Better understanding of the virus-host cell interaction could result in development of better prevention and treatment options. Here we show that the Akt inhibitor MK2206 blocks influenza pH1N1 virus infection in vitro . In particular, at noncytotoxic concentrations, MK2206 alters Akt signaling and inhibits endocytic uptake of the virus. Interestingly, MK2206 is unable to inhibit H3N2, H7N9, and H5N1 viruses, indicating that pH1N1 evolved specific requirements for efficient infection. Thus, Akt signaling could be exploited further for development of better therapeutics against pH1N1 virus.

Here we report full-length sequencing of the first large set of influenza A(H1N1)pdm09 virus genomes isolated in Finland between the years 2009 and 2013 and discuss the advantages and needs of influenza virus sequencing efforts.

Intraepidemic antigenic and genetic variation was indicated when H3N2-subtype influenza A virus strains isolated during the 1996–1997 epidemic season in Finland were studied for reactivity in the haemagglutination inhibition (HI) assay and for nucleotide sequences coding for the variable HA1 domain of viral haemagglutinin. Thirty prevaccination- and postvaccination-paired sera taken from subjects who had been vaccinated against influenza during the previous autumn were studied for the presence of HI antibody to the homologous vaccine virus A/Nanchang/933/95, and five field strains representing the genetic and antigenic variability of the 1996–1997 epidemic season. The lowest vaccination-induced HI titres in each of the three age groups were detected in the two field strains that had been isolated from vaccinated patients and belonged to two different genetic sublineages. The intraepidemic variability of the 1996–1997 field strains in HI reactivity may be indicative of circulation of virus strains that may be capable of breaking through vaccination-induced immunity better than the other strains. J. Med. Virol. 65:584–589, 2001. © 2001 Wiley-Liss, Inc.

Tutkimuksessa seurattiin männyn taimien orastumista neljällä äeskylvöalueella – Heinolassa, Kuorevedellä, Ruovedellä ja Sonkajärvellä. Kymmeneltä uudistusalalta laskettiin elävien männyn taimien lukumäärä muokkausjäljessä satunnaisesti sijoitetuilta 0,6 m2:n koealoilta kolmesti kylvökesänä sekä sitä seuraavan kasvukauden alussa ja lopussa. Kuudella alalla tehtiin käsinkylvöt samalla siemenerällä kuin konekylvöissä. Kylvö-muokkauskoneen toimintaa äeskylvössä seurattiin erillisessä kokeessa käyttämällä värjättyjä siemeniä ja laskemalla äesjäljistä löytyneet siemenet välittömästi kylvön jälkeen. Loppuinventoinnissa toisen vuoden syksyllä taimia oli Heinolan Kommerinkankaalla keskimäärin 2,93, Ruoveden Siikakankaalla 2,99, Kuorevedellä 2,79 ja Sonkajärvellä 0,56 kappaletta äesmetrillä. Tyhjien koealojen osuus vaihteli 14 prosentista 59 prosenttiin. Taimien frekvenssijakaumat olivat oikealle vinoja kaikissa inventoinneissa. Käsinkylvössä orastui noin puolet kylvetystä siemenestä ja kylvökohdissa oli keskimäärin 10–12 sirkkatainta elossa ensimmäisen kasvukauden lopulla. Värjätyn siemenen äeskylvössä kivennäismaapinnalle päätyi noin neljännes kokonaissiemenmäärästä. Tulosten mukaan muokkausjäljen laatuun ja siementen tasaiseen kylväytymiseen äesjälkeen on kiinnitettävä enemmän huomiota. Lisätutkimuksin on selvitettävä kylvökoneen toimintaa kenttäolosuhteissa sekä haettava ratkaisuja, joiden avulla siementen orastumista voidaan varmentaa.

Background: Swine influenza is an infectious acute respiratory disease of pigs caused by influenza A virus. We investigated the time of entry of swine influenza into the Finnish pig population. We also describe the molecular detection of two types of influenza A (H1N1) viruses in porcine samples submitted in 2009 and 2010. This retrospective study was based on three categories of samples: blood samples collected for disease monitoring from pigs at major slaughterhouses from 2007 to 2009; blood samples from pigs in farms with a special health status taken in 2008 and 2009; and diagnostic blood samples from pigs in farms with clinical signs of respiratory disease in 2008 and 2009. The blood samples were tested for influenza A antibodies with an antibody ELISA. Positive samples were further analyzed for H1N1, H3N2, and H1N2 antibodies with a hemagglutination inhibition test. Diagnostic samples for virus detection were subjected to influenza A M-gene-specific real-time RT-PCR and to pandemic influenza A H1N1-specific real-time RT-PCR. Positive samples were further analyzed with RT-PCRs designed for this purpose, and the PCR products were sequenced and sequences analyzed phylogenetically. Results: In the blood samples from pigs in special health class farms producing replacement animals and in diagnostic blood samples, the first serologically positive samples originated from the period July–August 2008. In samples collected for disease monitoring, < 0.1%, 0% and 16% were positive for antibodies against influenza A H1N1 in the HI test in 2007, 2008, and 2009, respectively. Swine influenza A virus of avian-like H1N1 was first detected in diagnostic samples in February 2009. In 2009 and 2010, the avian-like H1N1 virus was detected on 12 and two farms, respectively. The pandemic H1N1 virus (A(H1N1) pdm09) was detected on one pig farm in 2009 and on two farms in 2010. Conclusions: Based on our study, swine influenza of avian-like H1N1 virus was introduced into the Finnish pig population in 2008 and A(H1N1)pdm09 virus in 2009. The source of avian-like H1N1 infection could not be determined. Cases of pandemic H1N1 in pigs coincided with the period when the A(H1N1)pdm09 virus was spread in humans in Finland.

Background: Influenza B virus evolution is currently in a unique situation having two cocirculating main lineages B/Yamagata/16/88 (YM/88)-like and B/Victoria/2/87 (VI/87)-like viruses. Continuation of this bifurcation would mean development towards distinct forms resembling the HA subtypes of influenza A viruses. Objective: We wanted to examine both intraepidemic heterogeneity and recent evolution in these two lineages. The initial purpose was to determine the geographic distribution of the two sublineages of the VI/87-like viruses in Europe in 1989–1990 under circumstances of low epidemic activity. Due to the outbreaks of YM/88-like viruses since 1991, the study was extended to contain the evolution of these viruses and their genetic relationship with the vaccine strains of that time. Study design: The HA1 gene sequences of 33 influenza B strains isolated in ten European countries since 1989 were determined and compared with those available through databases or personal contacts. Results: The two main lineages, YM/88-like and VI/87-like viruses, both continued to circulate. In both lineages, changes in the potential glycosylation sites were observed. Two sublineages of the VI/87 lineage cocirculated during the 1989–1990 season with somewhat different geographic distributions. A high degree of intraepidemic heterogeneity was observed, as well as examples of conserved nucleotide sequences. Conclusions: It is important to follow the evolution and circulation of VI/87-like viruses. Current vaccines give poor or no protection against VI/87-like viruses in immunologically unprimed children or even in primed adults (Levandowski et al., 1991, Pyhala et al., 1994). Changes in the potential glycosylation pattern in the latest virus isolates of both main lineages have occured and it is interesting to see the significance of these changes to viral evolution.

The clinical picture of influenza may vary from mild respiratory infection to pneumonia requiring intensive care. Annual epidemics are most commonly caused by H3N2 or H1N1 type influenza A or influenza B viruses. The population's immune protection against a new virus type is low, whereupon morbidity and mortality may be high. Vaccinations are the most important means to decrease influenza morbidity. Annual variation and quick intercontinental migration of influenza viruses, combined with the possibility of the creation of reassortant viruses, are significant challenges for the development of influenza vaccines.

The first infection caused by pandemic influenza A(H1N1)2009 virus was confirmed in Finland on 10 May 2009. The spread of the disease and its impact were monitored using several surveillance systems, such as the national infectious disease register, notifications of clusters of influenza, influenza-like or influenza-related illnesses, as well as virological, hospital, case-based and mortality surveillance. The epidemic started in early October in the north and then spread to the south about two weeks later. Based on the data from laboratory-confirmed cases, the morbidity was highest in children. The daily number of patients hospitalised with influenza A(H1N1)2009 reached a maximum of over 400 in late November. Of the 1,580 hospitalised patients (median age 32 years), 672 (43%) had at least one chronic underlying illness, 35 (2%) were pregnant, 132 (8%) were treated in intensive care units and 74 (5%) required mechanical ventilation. The median age of patients admitted to intensive care units was 48 years and 78 ( 59%) of them had at least one chronic underlying disease, none were pregnant. Altogether 44 deaths related to influenza A(H1N1)2009 were recorded (median age 56 years): 40 belonged to high-risk groups on the basis of underlying chronic diseases. Combining data from different surveillance systems gave timely information about the spread of the pandemic and contributed to identifying risk groups.

Timely identification of respiratory pathogens is essential for appropriate patient care and cohorting. In order to do rapid identification-technology near the patient we utilized the field-deployable RAZOR EX-thermocycler with a reverse transcription real-time PCR assay that detects all subtypes of influenza A virus. In addition, we developed a RT PCR assay for specific detection of influenza A(H1N1)pdm09 virus. These assays amplified segments of the matrix (M)- and the hemagglutinin (HA)-gene, respectively. Detection limits of the M-gene and the influenza A(H1N1)pdm09-specific HA-gene assays were 0.15 PFU and 8.8 PFU per reaction, respectively. With 18 influenza A viruses of different subtypes and influenza B, C, and 7 other respiratory viruses the RAZOR EX and standard real-time PCR assay results were in total agreement. From 104 clinical samples identical results were obtained by both PCR methods. Additional 21 clinical samples were tested under field conditions with the RAZOR EX instrument. Results were achieved in 90 min, including 45 min for sample preparation and they were in complete agreement with those obtained by standard real-time PCR under laboratory conditions. These methods enable highly sensitive and rapid on-site diagnostics to reliably identify patients infected with influenza A, including the influenza A(H1N1)pdm09-virus.

Background Oseltamivir provides modest clinical benefits to children with influenza when started within 48 hours of symptom onset. The effectiveness of oseltamivir could be substantially greater if the treatment were started earlier during the course of the illness. Methods We carried out a randomized, double-blind, placebo-controlled trial of the efficacy of oseltamivir started within 24 hours of symptom onset in children 1-3 years of age with laboratory-confirmed influenza during the seasons of 2007-2008 and 2008-2009. Eligible children received either orally administered oseltamivir suspension or a matching placebo twice daily for 5 days. The children received clinical examinations, and the parents filled out detailed symptom diaries for 21 days. Results Of 408 randomized children who received the study drug (oseltamivir, 203, and placebo, 205), 98 had laboratory-confirmed influenza (influenza A, 79, and influenza B, 19). When started within 12 hours of the onset of symptoms, oseltamivir decreased the incidence of acute otitis media by 85% (95% confidence interval, 25%-97%), but no significant reduction was observed with treatment started within 24 hours. Among children with influenza A, oseltamivir treatment started within 24 hours shortened the median time to resolution of illness by 3.5 days (3.0 vs 6.5 days; P = .006) in all children and by 4.0 days (3.4 vs 7.3; P = .006) in unvaccinated children and reduced parental work absenteeism by 3.0 days. No efficacy was demonstrated against influenza B infections. Conclusions Oseltamivir treatment started within 24 hours of symptom onset provides substantial benefits to children with influenza A infection. Clinical trials registration. ClinicalTrials.gov identifier: NCT00593502.