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Objective To assess the public health risk to Singapore posed by the emergence of artemisinin-resistant (ART-R) malaria in the Greater Mekong Subregion (GMS). Methods We assessed the likelihood of importation of drug-resistant malaria into Singapore and the impact on public health of its subsequent secondary spread in Singapore. Literature on the epidemiology and contextual factors associated with ART-R malaria was reviewed. The epidemiology of malaria cases in Singapore was analysed. The vulnerability and receptivity of Singapore were examined, including the connectivity with countries reporting ART-R malaria, as well as the preparedness of Singaporean health authorities. Sources of information include international journals, World Health Organization guidelines, data from the Singapore Ministry of Health and National Public Health Laboratory of the National Centre for Infectious Diseases, and the International Air Transport Association. Results The importation of ART-R malaria into Singapore is possible given the close proximity and significant travel volume between Singapore and the GMS countries reporting artemisinin resistance. Singapore's vulnerability is further enhanced by the presence of foreign workers from neighbouring endemic countries. Nonetheless, the overall likelihood of such an event is low based on the rarity and decreasing trend of imported malaria incidence.​: With the presence of Anopheles vectors in Singapore, imported cases of drug-resistant malaria could cause secondary transmission. Nevertheless, the risk of sustained spread is likely to be mitigated by the comprehensive surveillance and control system in place for both infected vectors and human cases. Discussion This risk assessment highlights the need for a continued high degree of vigilance of ART-R malaria locally and globally to minimize the risk and public health impact of drug-resistant malaria in Singapore.

Singapore implements a school closure policy for institutional hand, foot, and mouth disease (HFMD) outbreaks, but there is a lack of empirical evidence on the effect of closure on HFMD transmission. We conducted a retrospective analysis of 197,207 cases of HFMD over the period 2003–2012 at the national level and of 57,502 cases in 10,080 institutional outbreaks over the period 2011–2016 in Singapore. The effects of school closure due to 1) institutional outbreaks, 2) public holidays, and 3) school vacations were assessed using a Bayesian time series modeling approach. School closure was associated with a reduction in HFMD transmission rate. During public holidays, average numbers of secondary cases having onset the week after dropped by 53% (95% credible interval 44–62%), and during school vacations, the number of secondary cases dropped by 7% (95% credible interval 3–10%). Schools being temporarily closed in response to an institutional outbreak reduced the average number of new cases by 1,204 (95% credible interval 1,140–1,297). Despite the positive effect in reducing transmission, the effect of school closure is relatively small and may not justify the routine use of this measure.

Background: Residents in nursing homes are at risk of high morbidity and mortality due to coronavirus disease 2019 (COVID-19). We report the first nursing home COVID-19 outbreak linked to a nursing staff’s household transmission through clinical, epidemiological, laboratory and phylogenetic investigations. Methods: Serial point prevalence testing was conducted among the residents and staff following identification of the index case (a symptomatic resident) with SARS-CoV-2 infection. Active contact tracing, screening of close contacts, whole genome sequencing and phylogenetic analysis were conducted to identify the source and extent of the outbreak. Results: Among the 108 residents and 56 healthcare workers (HCW) in the nursing home, 14 (13%) residents and two (3.6%) HCW were diagnosed with COVID-19, with case fatality rate of 28.6% (4/14) among the residents. Five residents were symptomatic (35.7%) and the others were asymptomatic (64.3%) before the point prevalence survey. The genomic virus typing in this nursing home outbreak was lineage B.6 which is rare among other GISAID clades globally but common regionally. Among the family contacts of the two infected healthcare workers, only one member was infected and had recent travel history. Interpretation: Nursing staffs can be a potential source of infection in nursing home. Through prompt active case finding, and infection prevention and control measures, the outbreak can be contained. Minimising community and household contacts among nursing care staffs may reduce the risk of SARS-CoV-2 introduction into nursing home. Funding: None. Conflict of Interest: The authors declared no conflict of interest. Ethical Approval: Data were collected under the Infectious Disease Act for outbreak investigation and approved by Ministry of Health, Singapore.

Aims: In Singapore, pneumococcal vaccination is recommended for the elderly (i.e. those ≥65 years of age) and people with chronic medical conditions. We investigated epidemiological characteristics associated with the uptake of pneumococcal vaccine based on a nationally representative cross-sectional sample of community-living adults aged ≥50 years. Methods: The data were obtained from the National Health Surveillance Survey (NHSS) 2013. Associations between pneumococcal vaccination and sociodemographic and health-related variables were analysed using univariable and multivariable logistic regression models. Results: Among 3672 respondents aged ≥50 years in the NHSS, 7.8% had taken the pneumococcal vaccination. A higher level of education and higher monthly household income were sociodemographic characteristics independently associated with pneumococcal vaccine uptake. Health-related characteristics predictive of pneumococcal vaccine uptake were better self-rated health and having a regular family doctor/general practitioner. Among those who responded to the two questions on vaccinations, 3.9% had been vaccinated against both seasonal influenza and pneumococcal infection, while 11.1% had taken only seasonal influenza vaccination in the past year. Conclusions: There is a need to boost pneumococcal vaccination coverage among community-dwelling older adults. These findings provide insights into reviewing and tailoring public-health strategies and programmes to increase vaccine uptake in at-risk population groups.

Cross-matching of records between Singapore's tuberculosis and HIV registries showed that 3.3% of individuals with tuberculosis (TB) were coinfected with HIV (2000-2014), the TB incidence among individuals with HIV infection was 1.65 per 100 person-years, and 53% of coinfections were diagnosed within 1 month of each other. The findings supported joint prevention programmes for early diagnosis and treatment.

Influenza is a major cause of mortality and morbidity. We aimed to examine the influenza-associated hospitalization rates and proportions for cardiovascular disease (CVD) in tropical Singapore. Hospital admissions for ischemic heart disease (IHD), congestive heart failure (CHF), and overall CVD were obtained from the national inpatient database for the period of 2010-2014. We used, as the key indicator of influenza virus activity, the overall proportion of specimens from outpatients with influenza-like illness in the community that tested positive for influenza as part of the national influenza surveillance program. The annual influenza-associated hospitalization rates per 100,000 person-years ranged from 9.5 to 12.2 for IHD, 7.7 to 9.1 for CHF, and 15.8 to 19.2 for overall CVD. The influenza-associated hospitalization rates increased with increasing age. Influenza was significantly associated with excess hospitalizations in elderly persons aged ≥80 years, with an excess hospitalization rate per 100,000 person-years of 242.7 for IHD (P = 0.02), 271.8 for CHF (P = 0.01), and 497.2 for overall CVD (P < 0.001). In the tropics, influenza accounts for excess cardiovascular-related hospitalizations, especially in the elderly.

We conducted a retrospective study of 40 case-patients and 58 controls as part of a nationwide investigation of a group B Streptococcus outbreak in Singapore in 2015. Eating a Chinese-style raw fish dish (yusheng) was a major risk factor for bacteremia, particularly caused by serotype III sequence type 283.

Singapore is situated in the tropics where the seasonality of influenza is not as well defined as that of temperate countries. We examined the circulation of influenza viruses in the community in terms of the characteristics of influenza activity. We reviewed laboratory-confirmed virological data collected between 2010 and 2014 under the national influenza surveillance programme. Influenza activity was measured by the proportion of specimens from outpatients with influenza-like illness tested positive for influenza virus based on 4-weekly moving interval. Seasonal epidemics occurred around the end of previous year or the beginning and middle of the year. Increases in influenza positivity were more pronounced when there was a change in the predominant circulating influenza virus type/subtype to influenza A(H3N2). Influenza epidemics lasted about 12 weeks on average, with longer duration when there was a change in the predominant influenza type/subtype and especially when it was associated with influenza A(H3N2). Continuous influenza surveillance is important as it could provide early warning of imminent surges in virus transmission, and allow for timely implementation of public health prevention and control interventions to minimize influenza-associated disease burden. J. Med. Virol. 88:2069-2077, 2016. © 2016 Wiley Periodicals, Inc.

Singapore has experienced periodic dengue epidemics despite maintaining a low Aedes house index. Each epidemic was associated with a switch in the predominant serotype. We investigated the temporal dynamics of dengue fever and dengue virus (DENV) and analyzed the epidemiological and entomological patterns of dengue in Singapore from 2004 to 2016. The case surveillance is based on a mandatory notification system that requires all medical practitioners to report clinically suspected and laboratory-confirmed cases. Circulating (DENV) serotypes are monitored through a virus surveillance program. Entomological surveillance involves inspections for larval breeding and monitoring of adults using gravitraps. Singapore experienced a similar epidemic pattern during 2004–2007 and 2013–2016. The pattern involved a 2-year DENV-1 epidemic occurring after a switch in the predominant serotype from DENV-2 to DENV-1, followed by a “lull” year. Thereafter, the predominant serotype switched back to DENV-2, tailed by a small-scale epidemic. Across the years, the highest incidence group was in the 25–44 years age group. The incidence rate of those aged ≥ 55 years was about half of that of the 15–24 years age group during DENV-1 predominant years. However, it was almost equal to the younger age group in DENV-2 predominant years. Types of Aedes aegypti breeding habitats remained similar. Dengue incidence was significantly higher in areas with high breeding percentage (BP) than areas with low BP (P < 0.05). In conclusion, the oscillation of DENV-1 and DENV-2, throughout the 13-year period, led to a cyclical epidemic pattern and older adults were more affected by DENV-2 than DENV-1. Published version

We conducted a pediatric seroprevalence study of dengue virus (DENV) infection in Singapore, a dengue endemic city-state. Residual sera from 1,200 Singapore residents aged 1-17 years seen in two hospitals between 2008 and 2010 were tested for anti-DENV IgG antibodies. The overall seroprevalence was 10.4% (95%CI: 8.7-12.1%). There had been a marked decline in seroprevalence in the 15-19-year age group over the last three decades, while the prevalence in the 1-5-year olds (12.6%) was significantly higher than that of the 1996-1997 pediatric survey (0.8%). The overall dengue seroprevalence in children and adolescents remained low.

Singapore is a tropical country with influenza seasons occurring bi-annually. We compared the profile of severely ill patients with laboratory confirmed influenza A(H1N1)pdm09 infection in Singapore during the pandemic and post-pandemic periods, and studied their risk factors associated with mortality.Three periods were defined for this study; pandemic period from 18 June to 29 August 2009, early post-pandemic period from 30 August 2009 to 12 February 2010, and late post-pandemic period from 13 February to 10 August 2010.A total of 172 severely ill patients were admitted to hospitals from 18 June 2009 to 10 August 2010, of whom 23.8% died. The median age in the late post-pandemic period was significantly older than that in the early post-pandemic period (52 years versus 35 years, P=0.02). The median age of patients who died was significantly older than those who survived (52 years versus 44 years, P0.01). The median length of stay under intensive care in the late post-pandemic period was twice that in the early post-pandemic (6 days versus 3 days, P=0.045). The proportion who died in the late post-pandemic period was more than 2.5 times that in the early post-pandemic period (29.8% versus 11.1%, P=0.043).Severely ill patients were of older age in the late post-pandemic period. Older age was also significantly associated with mortality. It is important to maintain heightened vigilance and continue the surveillance of severely ill patients with influenza post-pandemic, so that patients with suspected infections could be promptly identified for early diagnosis and treatment.

In May 2016, the WHO recommended a 9-12 month MDR-TB treatment regimen for pulmonary MDR-TB patients without confirmed resistance to a medicine in this regimen (excluding isoniazid resistance). The majority of MDR pulmonary TB (PTB) cases in Singapore originate from South-east Asian countries where capacity for full drug susceptibility testing (DST) is not widely available. We report the phenotypic drug susceptibility pattern of these cases to detemine their eligibility for the WHO shorter MDR-TB regimen. From 2002 to 2016, there were 214 foreign-born MDR PTB cases diagnosed in Singapore. These originated from Indonesia (n=76), Myanmar (n=54), China (n=37), Philiippines (n=18), Vietnam (n=15), India (n-7), Bangladesh (n=4) and others (n=3). Nine (4.2%) were XDR and 28 (13.1%) pre-XDR cases. Phenotypic DST showed 16.7% (35/209) resistance to ofloxacin, 5.2% (11/213) resistance to kanamycin, 23% (49/213) resistance to ethionamide, 47.2% (101/214) resistance to ethambutol, 56.7% (68/120) resistance to pyrazinamide and 5.4% (4/74) resistance to clofazimine. 151 (70.5%) of the 214 cases were resistant to at least one of these six constituent drugs of the WHO shorter MDR-TB treatment regimen, and only 15 (7%) showed confirmed susceptibility to all six drugs. The WHO shorter MDR-TB treatment regimen is not applicable in at least 70% of MDR-TB patients in South-east Asia if the patients in our study are representative of those in their countries.

Multidrug-resistant tuberculosis (MDR-TB) is a major public health challenge, with an estimated 480 000 new cases emerging globally each year [1]. Treatment success rates using the 20-month conventional World Health Organization (WHO) regimen have been low, being about 52% in 2013 [1]. Observational studies in Bangladesh and several African countries have shown success rates of 84% using a shorter regimen [2–4]. Based on these studies, in May 2016 the WHO conditionally recommended a standardised, shorter 9–12-month regimen for MDR pulmonary tuberculosis (PTB), comprising a 4–6-month intensive phase with a combination of kanamycin, moxifloxacin, prothionamide, clofazimine, pyrazinamide, high-dose isoniazid and ethambutol, followed by a 5-month continuation phase containing moxifloxacin, clofazimine, ethambutol and pyrazinamide [5]. Confirmed resistance (except to isoniazid) or suspected ineffectiveness to a drug in this regimen is one of the exclusion criteria [5]., About 30% of MDR pulmonary-TB patients in a SE Asian (Singaporean) sample are eligible for the WHO shorter regimen http://ow.ly/KF3330dMSVs

Summary Objectives We undertook an epidemiological review to determine the trend and characteristics of acute hepatitis E in Singapore over the last 12 years. Methods We analysed the epidemiological records of all laboratory-confirmed cases of acute hepatitis E maintained at the Communicable Diseases Division, Ministry of Health, from 2000 to 2011. Results A total of 540 laboratory-confirmed cases of acute hepatitis E was reported with more than half imported, mainly from India and Bangladesh. Among the indigenous cases, the mean annual incidence per 100,000 population increased from 0.05 in 2000–2002 to 0.92 in 2009–2011. There was a male predominance and the median age was 46 years. Among the 3 major ethnic groups of Singapore residents, Chinese and Indians had higher mean annual incidence rate compared to Malays. All the indigenous cases occurred singly and sporadically and could not be epidemiologically linked to one another by person, place or time. No common food item was implicated. Conclusions Indigenous acute hepatitis E has emerged as a major cause of acute viral hepatitis in Singapore. While epidemiological investigations are ongoing to elucidate the risk factors and modes of transmission, travellers should be reminded to practise a high standard of personal and food hygiene when visiting endemic countries.

A national pediatric survey was undertaken to determine the prevalence of hepatitis B virus markers in Singapore. The aim was to assess the impact of the national childhood immunization program against hepatitis B implemented for all newborns since 1987. The survey involved prospective collection of residual sera from Singapore residents aged 1–17 years attending inpatient services or day surgery in two public hospitals between August 2008 and July 2010. A total of 1,200 sera were collected comprising 400 in each of the three age groups of 1–6, 7–12, and 13–17 years. The sera were tested for hepatitis B surface antigen (HBsAg) and antibody to HBsAg (anti-HBs). Four of the 1,200 samples tested positive for HBsAg, giving an overall prevalence of 0.3%. One and three in the 7–12 years and 13–17 years age groups, respectively, were positive for HBsAg. About 40% possessed anti-HBs (≥10 mIU/ml); the antibody prevalence decreased significantly from 63.8% in children aged 1–6 years to 32.8% in 7–12 year olds, and 23.5% in 13–17 year olds (P

Introduction: Measles is an acute, highly communicable viral disease, with measles outbreaks usually occuring in settings where there are unvaccinated populations. After being notified of a cluster of five measles cases in a Singapore public hospital in August 2011, the Ministry of Health Singapore conducted an outbreak investigation.Methods: Active case detection was conducted, and all notified cases’ movement history within the hospital were reviewed to determine any common exposures in place and time. Cases were classified as nosocomial if they had contact with other measles cases in the hospital seven to 21 days before onset dates. Laboratory testing included serological and molecular diagnostic methods.Results: Of the 14 cases, seven cases were nosocomial cases. Investigations identified two wards where cases were epidemiologically linked. Two cases in Ward A were of D8 genotype and genotypically 100% identical, thus confirming a common source of infection. The six cases in Ward B (including one transferred from Ward A) had overlapping periods of admission and three cases were of the same D8 genotype, with a single nucleotide difference.Discussion: The epidemiological linkages of the cases and laboratory findings suggest nosocomial transmission in Wards A and B. As a result of this investigation, the hospital implemented a new policy of isolating suspected measles cases instead of waiting until they had been laboratory confirmed. This investigation emphasizes the importance of early identification and isolation of suspected measles cases within health care institutions and reinforces the requirement for high measles vaccination coverage of health care workers.

Background: During the period 2005 to 2015, there were 241 multidrug-resistant (MDR) TB cases diagnosed in Singapore. Of these, 183 (81.7%) were foreign-born. Using spoligotyping and MIRU-VNTR, we determined the pattern of MDRTB transmission in Singapore and compared the characteristics of the clustered versus non-clustered cases. Methods: The TB Notification Registry captures the drug susceptibility pattern of all Mycobacterium tuberculosis isolates grown in the two mycobacteriology laboratories in Singapore. Spoligotyping and MIRU-VNTR was performed on all MDR isolates at the Singapore Central TB Laboratory. Patient characteristics (age, ethnicity, country of origin, socioeconomic status), sputum smear status and strain (Beijing vs non-Beijing) of clustered versus non-clustered isolates was compared. Results: Of the 224 (93%) MDRTB cases with available DNA fingerprinting results, 77 (34.4%) cases belonged to 19 clusters with at least two MDR cases in each cluster (range 2-15 cases). In 2012, there was an MDRTB outbreak among 7 local-born persons. Compared to a median of 3 cases annually in the years 2005-2011, there were 6 local-born MDRTB cases in each of the years 2014 and 2015. Clustered cases were more likely to be male (OR 2.35, 95% CI 1.21-4.56, p=0.01), to be infected with the Beijing strain (OR 7.96, CI 3.46-18.30, p Conclusion: The recent rise in the number of MDRTB among local-born in Singapore is of concern. More effort and resources such as the increased use of rapid diagnostic tests for MDRTB are needed in the fight against this global threat.

Background: Dengue resurged in Singapore during 2013-14, causing an outbreak with unprecedented number of cases in the country. In the present study, we summarise the epidemiological, virological and entomological findings gathered through the dengue surveillance programme and highlight the drivers of the epidemic. We also describe how the surveillance system facilitated the preparedness to moderate epidemic transmission of dengue in the country. Methods: The case surveillance was based on a mandatory notification system that requires all medical practitioners to report clinically-suspected and laboratory-confirmed cases within 24 hours. The circulating Dengue virus (DENV) populations were monitored through an island wide virus surveillance programme aimed at determining the serotypes and genotypes of circulating virus strains. Entomological surveillance included adult Aedes surveillance as well as premise checks for larval breeding. Results: A switch in the dominant serotype from DENV-2 to DENV-1 in March 2013 signalled a potential spike in cases, and the alert was corroborated by an increase in average Aedes house index. The alert triggered preparedness and early response to moderate the impending outbreak. The two-year outbreak led to 22,170 cases in 2013 and 18,338 in 2014, corresponding to an incidence rate of 410.6 and 335.0 per 100,000 population, respectively. DENV-1 was the dominant serotype in 2013 (61.7 %, n = 5,071) and 2014 (79.2 %, n = 5,226), contributed largely by a newly-introduced DENV-1 genotype III strain. The percentage of houses with Ae. aegypti breeding increased significantly (p

Singapore is situated in the tropics where the seasonality of influenza is not as well defined as that of temperate countries. We examined the circulation of influenza viruses in the community in terms of the characteristics of influenza activity. We reviewed laboratory-confirmed virological data collected between 2010 and 2014 under the national influenza surveillance programme. Influenza activity was measured by the proportion of specimens from outpatients with influenza-like illness tested positive for influenza virus based on 4-weekly moving interval. Seasonal epidemics occurred around the end of previous year or the beginning and middle of the year. Increases in influenza positivity were more pronounced when there was a change in the predominant circulating influenza virus type/subtype to influenza A(H3N2). Influenza epidemics lasted about 12 weeks on average, with longer duration when there was a change in the predominant influenza type/subtype and especially when it was associated with influenza A(H3N2). Continuous influenza surveillance is important as it could provide early warning of imminent surges in virus transmission, and allow for timely implementation of public health prevention and control interventions to minimize influenza-associated disease burden. J. Med. Virol. 88:2069-2077, 2016. © 2016 Wiley Periodicals, Inc.

Erratum in - Correction: Temporal Patterns of Influenza A and B in Tropical and Temperate Countries: What Are the Lessons for Influenza Vaccination? PLoS One. 2016 May 2;11(5):e0155089. doi: 10.1371/journal.pone.0155089. Introduction: Determining the optimal time to vaccinate is important for influenza vaccination programmes. Here, we assessed the temporal characteristics of influenza epidemics in the Northern and Southern hemispheres and in the tropics, and discuss their implications for vaccination programmes. Methods: This was a retrospective analysis of surveillance data between 2000 and 2014 from the Global Influenza B Study database. The seasonal peak of influenza was defined as the week with the most reported cases (overall, A, and B) in the season. The duration of seasonal activity was assessed using the maximum proportion of influenza cases during three consecutive months and the minimum number of months with 80% of cases in the season. We also assessed whether co-circulation of A and B virus types affected the duration of influenza epidemics. Results: 212 influenza seasons and 571,907 cases were included from 30 countries. In tropical countries, the seasonal influenza activity lasted longer and the peaks of influenza A and B coincided less frequently than in temperate countries. Temporal characteristics of influenza epidemics were heterogeneous in the tropics, with distinct seasonal epidemics observed only in some countries. Seasons with co-circulation of influenza A and B were longer than influenza A seasons, especially in the tropics. Discussion: Our findings show that influenza seasonality is less well defined in the tropics than in temperate regions. This has important implications for vaccination programmes in these countries. High-quality influenza surveillance systems are needed in the tropics to enable decisions about when to vaccinate. The Global Influenza B Study is supported by an unrestricted research grant from Sanofi Pasteur. info:eu-repo/semantics/publishedVersion

Field epidemiology involves the implementation of quick and targeted public health interventions with the aid of epidemiological methods. In this article, we share our practical experiences in outbreak management and in safeguarding the population against novel diseases. Given that cities represent the financial nexuses of the global economy, global health security necessitates the safeguard of cities against epidemic diseases. Singapore's public health landscape has undergone a systemic and irreversible shift with global connectivity, rapid urbanization, ecological change, increased affluence, as well as shifting demographic patterns over the past two decades. Concomitantly, the threat of epidemics, ranging from severe acute respiratory syndrome and influenza A (H1N1) to the resurgence of vector-borne diseases as well as the rise of modern lifestyle-related outbreaks, have worsened difficulties in safeguarding public health amidst much elusiveness and unpredictability. One critical factor that has helped the country overcome these innate and man-made public health vulnerabilities is the development of a resilient field epidemiology service, which includes our enhancement of surveillance and response capacities for outbreak management, and investment in public health leadership. We offer herein the Singapore story as a case study in meeting the challenges of disease control in our modern built environment.

Background We assessed the seroepidemiology of pertussis, diphtheria and poliovirus antibodies in a cohort of highly immunized children, together with the burden of these diseases in Singapore. Methods Hospital residual sera collected between August 2008 and July 2010 from 1200 children aged 1–17 years were tested for the prevalence of IgG antibodies against Bordetella pertussis , diphtheria toxoid, and all three poliovirus types by enzyme-linked immunosorbent assays. Results We found an overall seroprevalence of 99.4% (95% CI 98.8–99.7%) for diphtheria, and 92.3% (95% CI 90.6–93.6%) for poliomyelitis, along with no indigenous cases of these diseases since 1993. However, the seroprevalence for pertussis was 60.8% (95% CI 58.0–63.5%) only. Among the subjects who had completed three doses of pertussis vaccination by the age of 2 years ( n = 1092), the pertussis seroprevalence was 85.0% (95% CI 79.7–89.2%) in those who received the last vaccination within a year before the study, and it decreased to 75.0% (95% CI 64.5–83.2%) and 63.1% (95% CI 50.9–73.8%) in those who had the last vaccination 1 year and 2 years before the study, respectively. The seroprevalence remained at about 50% for those whose last pertussis vaccination was administered 4 years and longer before the study. Conclusions The high seroprevalence for poliomyelitis and diphtheria confer solid herd immunity to eliminate these diseases in Singapore. In contrast, immunity against pertussis waned considerably over time, and routine boosters should be given to adolescents to ensure sustained immunity against pertussis.

From 29 June to 7 July 2009, Singapore hosted the inaugural Asian Youth Games (AYG), which brought 1210 athletes and 810 officials from 43 participating countries. On 11 June, just 1 week before the Games Village Medical Centre started operations, the World Health Organization officially declared a global H1N1 2009 pandemic. Working in close partnership with the Olympic Council of Asia Medical Commission, Singapore AYG Organising Committee and other government agencies, the AYG Medical Services Committee was successful in preventing the local transmission of H1N1, which would have been a threat to the games, as it could have led to the cancellation of these games. This article describes the experience and valuable lessons learnt from managing a sports-related mass gathering during the developing pandemic.

We describe the public health control measures implemented in Singapore to limit the spread of influenza A (H1N1-2009) and mitigate its social effects. We also discuss the key learning points from this experience. Singapore’s public health control measures were broadly divided into 2 phases: containment and mitigation. Containment strategies included the triage of febrile patients at frontline healthcare settings, admission and isolation of confirmed cases, mandatory Quarantine Orders (QO) for close contacts, and temperature screening at border entry points. After sustained community transmission became established, containment shifted to mitigation. Hospitals only admitted H1N1-2009 cases based on clinical indications, not for isolation. Mild cases were managed in the community. Contact tracing and QOs tapered off, and border temperature screening ended. The 5 key lessons learnt were: (1) Be prepared, but retain flexibility in implementing control measures; (2) Surveillance, good scientific information and operational research can increase a system’s ability to manage risk during a public health crisis; (3) Integrated systems-level responses are essential for a coherent public health response; (4) Effective handling of manpower surges requires creative strategies; and (5) Communication must be strategic, timely, concise and clear. Singapore’s effective response to the H1N1-2009 pandemic, founded on experience in managing the 2003 SARS epidemic, was a whole-of-government approach towards pandemic preparedness planning. Documenting the measures taken and lessons learnt provides a learning opportunity for both doctors and policy makers, and can help fortify Singapore’s ability to respond to future major disease outbreaks. Key words: Communications, Preparedness, Surge capacity

Introduction: Singapore was substantially affected by three 20th Century pandemics. This study describes the course of the pandemics, and the preventive measures adopted. Materials and Methods: We reviewed and researched a wide range of material including peer-reviewed journal articles, Ministry of Health reports, Straits Settlements reports and newspaper articles. Monthly mortality data were obtained from various official sources in Singapore. Results: The 1918 epidemic in Singapore occurred in 2 waves – June to July, and October to November – resulting in up to 3500 deaths. The 1957 epidemic occurred in May, and resulted in widespread morbidity, with 77,000 outpatient attendances in government clinics alone. The 1968 epidemic occurred in August and lasted a few weeks, with outpatient attendances increasing by more than 65%. The preventive measures instituted by the Singapore government during the pandemics included the closure of schools, promulgation of public health messages, setting up of influenza treatment centres, and screening at ports. Students, businessmen and healthcare workers were all severely affected by the pandemics. Conclusions: Tropical cities should be prepared in case of a future pandemic. Some of the preventive measures used in previous pandemics may be applicable during the next pandemic.

The national strategy against pandemic influenza essentially consists of 3 prongs: (i) effective surveillance, (ii) mitigation of the pandemic’s impact, and (iii) render the population immune through vaccination. When the pandemic hits Singapore, the response plan aims to achieve the following 3 outcomes: (i) maintenance of essential services to limit social and economic disruption, (ii) reduction of morbidity and mortality through antiviral treatment, and (iii) slow and limit the spread of influenza to reduce the surge on healthcare services. The biggest challenge will come from managing the surge of demand on healthcare services. A high level of preparedness will help healthcare services better cope with the surge. Key words: Essential services, Healthcare, National preparedness, Non-pharmaceutical measures

Pandemic preparedness plans must include cities that are global trading hubs., Tropical cities such as Singapore do not have well-defined influenza seasons but have not been spared from influenza pandemics. The 1918 epidemic in Singapore, which was then already a major global trading hub, occurred in 2 waves, June–July, and October–November, and resulted in >2,870 deaths. The excess mortality rate was higher than that for industrialized nations in the Northern Hemisphere but lower than that for less industrialized countries in Asia and Africa. The 1957 epidemic occurred in May and resulted in widespread illness. The 1968 epidemic occurred in August and lasted a few weeks, again with widespread illness. Tropical cities may be affected early in a pandemic and have higher mortality rates. With the increase in travel and trade, a future pandemic may reach a globally connected city early and spread worldwide. Preparedness and surveillance plans must be developed to include the megacities of the tropical world.

We conducted a pediatric seroprevalence study of dengue virus (DENV) infection in Singapore, a dengue endemic city-state. Residual sera from 1,200 Singapore residents aged 1-17 years seen in two hospitals between 2008 and 2010 were tested for anti-DENV IgG antibodies. The overall seroprevalence was 10.4% (95%CI: 8.7-12.1%). There had been a marked decline in seroprevalence in the 15-19-year age group over the last three decades, while the prevalence in the 1-5-year olds (12.6%) was significantly higher than that of the 1996-1997 pediatric survey (0.8%). The overall dengue seroprevalence in children and adolescents remained low.

Dengue is endemic in Singapore, and the most recent epidemic occurred in 2013. The mean of weekly number of dengue cases over a five-year period provides an indication of the baseline level. In view of increased laboratory testing for dengue in 2013, an adjustment was made to the computation of the baseline level for 2014. The assumption for our approach in incorporating an adjustment factor was that the proportion of hospitalizations among laboratory-confirmed cases remained constant between 2012 and 2013. This adjustment has helped to provide a more accurate indication of the baseline level of dengue for 2014.

Severe acute respiratory syndrome (SARS) was imported into Singapore in late February 2003 by a local resident who returned from a holiday in Hong Kong and started an outbreak in the hospital where she was admitted on 1 March 2003. The disease subsequently spread to 4 other healthcare institutions and a vegetable wholesale centre. During the period between March and May 2003, 238 probable SARS cases, including 8 imported cases and 33 deaths, were reported. Transmission within the healthcare and household settings accounted for more than 90% of the cases. Factors contributing to the spread of infection included the failure to recognise the high infectivity of this novel infection, resulting in a delay in isolating initial cases and contacts and the implementation of personal protective measures in healthcare institutions; and the super-spreading events by 5 index cases, including 3 with co-morbid conditions presenting with atypical clinical manifestations of SARS. Key public health measures were directed at prevention and control within the community and hospitals, and the prevention of imported and exported cases. An isolated laboratory-acquired case of SARS was reported on 8 September 2003. Based on the lessons learnt, Singapore has further strengthened its operational readiness and laboratory safety to respond to SARS, avian flu and other emerging diseases.

Objective In line with regional and global goals for the elimination of rubella and congenital rubella syndrome (CRS), we reviewed the epidemiological situation in Singapore, based on surveillance reports on rubella and CRS, national immunization coverage and seroprevalence surveys. The aim of our review was to identify current gaps and steps taken to achieve the targets set by the World Health Organization (WHO) Western Pacific Regional Office (WPRO). Methods Epidemiological data on clinical and laboratory-confirmed rubella cases, including CRS, notified to the Communicable Diseases Division, Ministry of Health, Singapore, from 2003 to 2013 were collated and analyzed. Vaccination coverage against rubella was obtained from the National Immunization Registry and School Health Services of the Health Promotion Board. The changing prevalence of rubella was determined from periodic serological surveys. Findings The incidence of indigenous rubella cases per million population decreased from 37.2 in 2008 to 7.6 in 2013 and there had been no indigenous case of CRS in 2012 and 2013. Therapeutic abortions performed due to rubella infections had become uncommon. The annual measles, mumps, and rubella (MMR) vaccination coverage in childhood population remained high ranging from 93% to 96%. The overall susceptibility to rubella in women aged 18–44 years had reduced significantly from 15.8% in 2004 to 11.0% in 2010. The prevalence of IgG antibody against rubella among Singapore children aged 1–17 years was maintained at 87.3% in 2008–2010. Conclusion All available data indicated that Singapore has made good progress towards the elimination of rubella and CRS. It has attained the targets set by the WHO WPRO for 2015. In preparation for verification of rubella elimination, an enhanced surveillance system has been implemented to ensure that all reported cases are laboratory confirmed, and genotyping of rubella virus strains isolated is carried out to provide evidence for interruption of endemic transmission.

Coxsackieviruses A6 (CV-A6) and A16 (CV-A16) and Enterovirus 71 (EV-A71) have caused periodic epidemics of hand, foot and mouth disease (HFMD) among children in Singapore. We conducted a cross-sectional study to estimate the seroprevalence of these enteroviruses among Singapore children and adolescents. The study was conducted between August 2008 and July 2010. It involved 700 Singapore residents aged 1–17 years whose residual sera were obtained following the completion of routine biochemical investigations in two public acute-care hospitals. The levels of neutralizing antibodies (NtAb) against CV-A6, CV-A16 and EV-A71 were analyzed by the microneutralization test. The age-specific geometric mean titer (GMT) of antibodies against each of the three enteroviruses and the 95% confidence intervals (CI) were calculated. The seroprevalence of CV-A6 and CV-A16 was high at 62.7% (95% CI: 59.1–66.2%) and 60.6% (95% CI: 56.9–64.1%), respectively. However, the seroprevalence of EV-A71 was significantly lower at 29.3% (95% CI: 26.0–32.8%). About 89.7% of the children and adolescents had been infected by at least one of the three enteroviruses by 13–17 years of age. About half (52.3%) were seropositive for two or all three enteroviruses, while only 16.1% had no NtAb against any of the three enteroviruses. High NtAb levels were observed in the younger age groups. CV-A6 and CV-A16 infections are very common among Singapore children and adolescents, while EV-A71 infections are less common. Infection is continually acquired from early childhood to adolescent age.