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Swine are regarded as a mixing vessel for influenza A viruses (IAVs) (1). Avian, swine, and human IAVs can co-infect pigs and generate novel reassortants of zoonotic or pandemic potential. [...]

Cross-reactive antibodies with Fc receptor (FcR) effector functions may mitigate pandemic virus impact in the absence of neutralizing antibodies. In this exploratory study, we use serum from a randomized placebo-controlled trial of seasonal trivalent influenza vaccination in children (NCT00792051) conducted at the onset of the 2009 H1N1 pandemic (pH1N1) and monitored for infection. We found that seasonal vaccination increases pH1N1 specific antibodies and FcR effector functions. Furthermore, prospective baseline antibody profiles after seasonal vaccination, prior to pH1N1 infection, show that unvaccinated uninfected children have elevated ADCC effector function, FcγR3a and FcγR2a binding antibodies to multiple pH1N1 proteins, past seasonal and avian (H5, H7 and H9) strains. Whereas, children that became pH1N1 infected after seasonal vaccination have antibodies focussed to seasonal strains without FcR functions, and greater aggregated HA-specific profiles for IgM and IgG3. Modeling to predict infection susceptibility, ranked baseline hemagglutination antibody inhibition as the highest contributor to lack of pH1N1 infection, in combination with features that include pH1-IgG1, H1-stem responses and FcR binding to seasonal vaccine and pH1 proteins. Thus, seasonal vaccination can have benefits against pandemic influenza viruses, and some children already have broadly reactive antibodies with Fc potential without vaccination and may be considered 'elite influenza controllers'. In this study, the authors assessed influenza-specific antibody responses in a cohort of seasonally vaccinated children and report that seasonal vaccination is beneficial by enhancing pandemic influenza virus-specific antibodies and cross-reactive effector functions. [ABSTRACT FROM AUTHOR]

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) lineage B.1.617 (1) and 3 of its sublineages, B.1.617.1 (Kappa), B.1.617.2 (Delta), and B.1.617.3, were first detected in India. The Delta variant started [...]

The SARS-CoV-2 Omicron variant (Pango lineage B.1.1.529) emerged in November 2021. Within a few weeks, subvariants BA.1, BA.1.1, and BA.2 were detected in varying proportions on different continents, but BA.1 [...]

Hong Kong, China, has had 4 waves of coronavirus disease (COVID-19) outbreaks since the emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in December 2019. By February 1, 2021, [...]

A new variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), B.1.1.529, was identified in Botswana and South Africa in early November 2021 and was designated as variant of concern [...]

Hong Kong uses an elimination strategy to control coronavirus disease (COVID-19) that includes stringent travel restrictions to reduce the risk of introducing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) into [...]

To investigate a superspreading event at a fitness center in Hong Kong, China, we used genomic sequencing to analyze 102 reverse transcription PCR-confirmed cases of severe acute respiratory syndrome coronavirus [...]

Since the emergence of SARS-CoV-2, different variants and subvariants successively emerged to dominate global virus circulation as a result of immune evasion, replication fitness or both. COVID-19 vaccines continue to be updated in response to the emergence of antigenically divergent viruses, the first being the bivalent RNA vaccines that encodes for both the Wuhan-like and Omicron BA.5 subvariant spike proteins. Repeated infections and vaccine breakthrough infections have led to complex immune landscapes in populations making it increasingly difficult to assess the intrinsic neutralizing antibody responses elicited by the vaccines. Hong Kong's intensive COVID-19 containment policy through 2020–2021 permitted us to identify sera from a small number of infection-naïve individuals who received 3 doses of the RNA BNT162b2 vaccine encoding the Wuhan-like spike (WT) and were boosted with a fourth dose of the WT vaccine or the bivalent WT and BA.4/5 spike (WT + BA.4/5). While neutralizing antibody to wild-type virus was comparable in both vaccine groups, BNT162b2 (WT + BA.4/BA.5) bivalent vaccine elicited significantly higher plaque neutralizing antibodies to Omicron subvariants BA.5, XBB.1.5, XBB.1.16, XBB.1.9.1, XBB.2.3.2, EG.5.1, HK.3, BA.2.86 and JN.1, compared to BNT162b2 monovalent vaccine. The single amino acid substitution that differentiates the spike of JN.1 from BA.2.86 resulted in a profound antigenic change. [ABSTRACT FROM AUTHOR]

On December 19, 2017, a high number of dead birds from various species was reported in a live bird market in Riyadh, Saudi Arabia, by the Department of Animal Resources [...]

Background The epidemiological advantage of Omicron variant is evidenced by its rapid spread and the ability to outcompete prior variants. Among Omicron sublineages, early outbreaks were dominated by BA.1, while BA.2 has gained dominance since February 2022. The relative pathogenicity and transmissibility of BA.1 and BA.2 have not been fully defined. Methods We compared viral loads and clinical signs in Syrian hamsters after infection with BA.1, BA.2, or D614G variant. A competitive transmission model and next-generation sequencing were used to compare the relative transmission potential of BA.1 and BA.2. Results BA.1 and BA.2 caused no apparent clinical signs, while D614G caused more than 10% weight loss. Higher viral loads were detected in nasal wash samples and nasal turbinate and lung tissues from BA.1-inoculated hamsters compared with BA.2-inoculated hamsters. No aerosol transmission was observed for BA.1 or BA.2 under the experimental condition in which D614G transmitted efficiently. BA.1 and BA.2 were able to transmit among hamsters via direct contact; however, BA.1 transmitted more efficiently than BA.2 under the competitive transmission model. No recombination was detected from direct contacts exposed simultaneously to BA.1 and BA.2. Conclusions Omicron BA.1 and BA.2 demonstrated attenuated pathogenicity and reduced transmission potential in hamsters compared with early SARS-CoV-2 strains. [ABSTRACT FROM AUTHOR]

Background: Measures for mitigation of Coronavirus Disease 2019 (COVID‐19) were set to reduce the spread of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS‐CoV‐2). SARS‐CoV‐2 and other respiratory viruses share similar transmission routes and some common clinical manifestations. Co‐circulation of SARS‐CoV‐2 and other common respiratory viruses is imminent. Therefore, development of multiplex assays for detecting these respiratory viruses is essential for being prepared for future outbreaks of respiratory viruses. Methods: A panel of three reverse transcription droplet digital PCR (RT‐ddPCR) assays were developed to detect 15 different human respiratory viruses. Evaluations of its performance were demonstrated. A total of 100 local and 98 imported COVID‐19 cases in Hong Kong were screened for co‐infection with other common respiratory viruses. Results: All detected viral targets showed distinct signal clusters using the multiplex RT‐ddPCR assays. These assays have a broad range of linearity and good intra‐/inter‐assay reproducibility for each target. The lower limits of quantification for all targets were ≤46 copies per reaction. Six imported cases of COVID‐19 were found to be co‐infected with other respiratory viruses, whereas no local case of co‐infection was observed. Conclusions: The multiplex RT‐ddPCR assays were demonstrated to be useful for screening of respiratory virus co‐infections. The strict preventive measures applied in Hong Kong may be effective in limiting the circulation of other human respiratory viruses. The multiplex assays developed in this study can achieve a robust detection method for clinical and research purposes. [ABSTRACT FROM AUTHOR]

This document is a correction notice for an article titled "Influenza antibody breadth and effector functions are immune correlates from acquisition of pandemic infection of children" published in Nature Communications. The correction addresses errors in the original version of the article, including incorrect p-values for certain figures, mislabeling of panels, missing information in the legend, and a missing funding source in the acknowledgement section. These errors have been corrected in both the PDF and HTML versions of the article. The authors of the article are Janice Z. Jia, Carolyn A. Cohen, Haogao Gu, Milla R. McLean, Raghavan Varadarajan, Nisha Bhandari, Malik Peiris, Gabriel M. Leung, Leo L. M. Poon, Tim Tsang, Amy W. Chung, Benjamin J. Cowling, Nancy H. L. Leung, and Sophie A. Valkenburg. [Extracted from the article]

Several zoonotic influenza A viruses detected in humans contain genes derived from avian H9N2 subtypes. We uncovered a Eurasian avian-like H1N1 swine influenza virus with polymerase basic 1 and matrix gene segments derived from the H9N2 subtype, suggesting that H9N2 viruses are infecting pigs and reassorting with swine influenza viruses in China. [ABSTRACT FROM AUTHOR]

We sequenced ≈50% of coronavirus disease cases imported to Hong Kong during March-July 2021 and identified 70 cases caused by Delta variants of severe acute respiratory syndrome coronavirus 2. The genomic diversity detected in Hong Kong was similar to global diversity, suggesting travel hubs can play a substantial role in surveillance. [ABSTRACT FROM AUTHOR]

Coronavirus disease 2019 (COVID-19) is a global health concern as it continues to spread within China and beyond. The causative agent of this disease, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), belongs to the genus Betacoronavirus , which also includes severe acute respiratory syndrome-related coronavirus (SARSr-CoV) and Middle East respiratory syndrome-related coronavirus (MERSr-CoV). Codon usage of viral genes are believed to be subjected to different selection pressures in different host environments. Previous studies on codon usage of influenza A viruses helped identify viral host origins and evolution trends, however, similar studies on coronaviruses are lacking. In this study, we compared the codon usage bias using global correspondence analysis (CA), within-group CA and between-group CA. We found that the bat RaTG13 virus best matched the overall codon usage pattern of SARS-CoV-2 in orf1ab, spike and nucleocapsid genes, while the pangolin P1E virus had a more similar codon usage in membrane gene. The amino acid usage pattern of SARS-CoV-2 was generally found similar to bat and human SARSr-CoVs. However, we found greater synonymous codon usage differences between SARS-CoV-2 and its phylogenetic relatives on spike and membrane genes, suggesting these two genes of SARS-CoV-2 are subjected to different evolutionary pressures. [ABSTRACT FROM AUTHOR]