A joint analysis of influenza-associated hospitalizations and mortality in Hong Kong, 1998–2013

published_or_final_versio

Brief Report: Incubation Period Duration and Severity of Clinical Disease Following Severe Acute Respiratory Syndrome Coronavirus Infection

postprin

The effect of age and recent influenza vaccination history on the immunogenicity and efficacy of 2009-10 seasonal trivalent inactivated influenza vaccination in children

published_or_final_versio

Interpreting Seroepidemiologic Studies of Influenza in a Context of Nonbracketing Sera

Background: In influenza epidemiology, analysis of paired sera collected from people before and after influenza seasons has been used for decades to study the cumulative incidence of influenza virus infections in populations. However, interpretation becomes challenging when sera are collected after the start or before the end of an epidemic, and do not neatly bracket the epidemic. Methods: Serum samples were collected longitudinally in a community-based study. Most participants provided their first serum after the start of circulation of influenza A(H1N1)pdm09 virus in 2009. We developed a Bayesian hierarchical model to correct for nonbracketing sera and estimate the cumulative incidence of infection from the serological data and surveillance data in Hong Kong. Results: We analyzed 4,843 sera from 2,097 unvaccinated participants in the study, collected from April 2009 to December 2010. After accounting for nonbracketing, we estimated that the cumulative incidence of H1N1pdm09 virus infection was 45% (95% credible interval [CI] = 40%, 49%), 17% (95% CI = 13%, 20%), and 11% (95% CI = 6%, 18%) for children ages 0–18 years, adults 19–50 years, and older adults >50 years, respectively. Including all available data substantially increased precision compared with a simpler analysis based only on sera collected at 6-month intervals in a subset of participants. Conclusions: We developed a framework for the analysis of antibody titers that accounted for the timing of sera collection with respect to influenza activity and permitted robust estimation of the cumulative incidence of infection during an epidemic.postprin

Variability in the immunogenicity of inactivated seasonal influenza vaccine in children due to age and recent previous influenza vaccination

Poster Session: VaccinesBackground: Annual receipt of trivalent inactivated influenza (TIV) vaccination is recommended for school-age children in some countries. However, there is little data on the variability of the immunogenicity of influenza vaccination in children and how this is affected by their age and recent influenza vaccination history. Materials and Methods: We used data on children in a Hong Kong community-based study who were randomized to receive TIV before the 2009-2010 influenza season. Antibody titers against seasonal and pandemic A(H1N1), seasonal A(H3N2), and two B influenza viruses (B/Brisbane and B/Florida) were measured by hemagglutination inhibition immediately before and 1 month after vaccination (Cowling et al. Clin Infect Dis. 2012). Multivariate regression models were fitted in a Bayesian framework to characterize the distribution of changes in antibody titers following vaccination and update previous findings by considering the correlation between virus strains (Ng et al. Pediatr Infect Dis J. 2013). Results: In 452 subjects, statistically significant rises in the geometric means of all antibody titers were observed, with those against the virus strains included in the TIV rising by geometric means of 7.95 to 13.36; those against pandemic A(H1N1) and B/Florida rose by 1.47 and 4.21, respectively. Geometric standard deviations were between 3.76 and 8.41 around the geometric means, with pandemic A(H1N1) showing the least variability in rises. The most closely correlated titer increases were those for the two influenza B viruses, while increases in pandemic A(H1N1) titers were unrelated to any other titer. Being vaccinated in either of the two previous years significantly reduced the increase in seasonal A(H1N1) and A(H3N2) antibody titers, while among children not vaccinated in the previous 2 years, those aged > 9 years experienced significantly higher increases in the influenza B titers than those aged 6-8 years. Conclusions: Increases in antibody titers following vaccination can vary depending on age and vaccination history. Results from our study suggest that humoral antibody response to TIV may be lower in children receiving repeated vaccination, but receipt of TIV induced seroprotection in most subjects.published_or_final_versio

Population-Based Pediatric Hospitalization Burden of Lineage-Specific Influenza B in Hong Kong, 2004–2014

postprin

A Smart Card-Based Electronic School Absenteeism System for Influenza-Like Illness Surveillance in Hong Kong: Design, Implementation, and Feasibility Assessment

published_or_final_versio

Increased risk of noninfluenza respiratory virus infections associated with receipt of inactivated influenza vaccine

We randomized 115 children to trivalent inactivated influenza vaccine (TIV) or placebo. Over the following 9 months, TIV recipients had an increased risk of virologically-confirmed non-influenza infections (relative risk: 4.40; 95 confidence interval: 1.31-14.8). Being protected against influenza, TIV recipients may lack temporary non-specific immunity that protected against other respiratory viruses. © 2012 The Author.postprin

Determinants of serum 25-hydroxyvitamin D in Hong Kong

Vitamin D plays an important role in skeletal health throughout life. Some studies have hypothesised that vitamin D may reduce the risk of other diseases. Our study aimed to estimate age-specific and sex-specific serum 25-hydroxyvitamin D (25(OH)D) status and to identify the determinants of serum 25(OH)D status in Hong Kong, a subtropical city in southern China. In 2009-2010, households in Hong Kong were followed up to identify acute respiratory illnesses, and sera from 2694 subjects were collected in three to four different study phases to permit measurement of 25(OH)D levels at different times of the year. A questionnaire survey on diet and lifestyle was conducted among children, with simultaneous serum collection in April and May 2010. The mean of serum 25(OH)D levels in age groups ranged from 39 to 63 nmol/l throughout the year with the mean values in all age groups in spring below 50 nmol/l. Children aged 6-17 years, and girls and women had significantly lower serum 25(OH)D levels than adults, and boys and men, respectively (all P< 0·001). We estimated that serum 25(OH)D levels in Hong Kong followed a lagged pattern relative to climatic season by 5 weeks with lowest observed levels in early spring (March). For children aged 6-17 years, reporting a suntan, having at least 1 servings of fish/week and having at least 1 serving of eggs/week were independently associated with higher serum 25(OH)D levels. Adequate sunlight exposure and increased intake of dietary vitamin D could improve vitamin D status, especially for children and females in the winter and spring.postprin

A comparative study of clinical presentation and risk factors for adverse outcome in patients hospitalised with acute respiratory disease due to MERS coronavirus or other causes

Middle East Respiratory syndrome (MERS) first emerged in Saudi Arabia in 2012 and remains a global health concern. The objective of this study was to compare the clinical features and risk factors for adverse outcome in patients with RT-PCR confirmed MERS and in those with acute respiratory disease who were MERS-CoV negative, presenting to the King Fahad Medical City (KFMC) in Riyadh between October 2012 and May 2014. The demographics, clinical and laboratory characteristics and clinical outcomes of patients with RT-PCR confirmed MERS-CoV infection was compared with those testing negative MERS-CoV PCR. Health care workers (HCW) with MERS were compared with MERS patients who were not health care workers. One hundred and fifty nine patients were eligible for inclusion. Forty eight tested positive for MERS CoV, 44 (92%) being hospital acquired infections and 23 were HCW. There were 111 MERS-CoV negative patients with acute respiratory illnesses included in this study as 'negative controls'. Patient with confirmed MERS-CoV infection were not clinically distinguishable from those with negative MERS-CoV RT-PCR results although diarrhoea was commoner in MERS patients. A high level of suspicion in initiating laboratory tests for MERS-CoV is therefore indicated. Variables associated with adverse outcome were older age and diabetes as a co-morbid illness. Interestingly, co-morbid illnesses other than diabetes were not significantly associated with poor outcome. Health care workers with MERS had a markedly better clinical outcome compared to non HCW MERS patients.published_or_final_versio