Contrasting SARS-CoV-2 epidemics in Singapore: cohort studies in migrant workers and the general population.

IMPORTANCE: Since January 2020, Singapore has implemented comprehensive measures to suppress SARS-CoV-2. Despite this, the country has experienced contrasting epidemics, with limited transmission in the community and explosive outbreaks in migrant worker dormitories. OBJECTIVE: To estimate SARS-CoV-2 infection incidence among migrant workers and the general population in Singapore. DESIGN: Prospective serological cohort studies. SETTING: Two cohort studies - in a migrant worker dormitory and in the general population in Singapore. PARTICIPANTS: 478 residents of a SARS-CoV-2-affected migrant worker dormitory were followed up between May and July 2020, with blood samples collected on recruitment and after 2 and 6 weeks. In addition, 937 community-dwelling adult Singapore residents, for whom pre-pandemic sera were available, were recruited. These individuals also provided a serum sample on recruitment in November/December 2020. EXPOSURE: Exposure to SARS-CoV-2 in a densely populated migrant worker dormitory and in the general population. MAIN OUTCOMES AND MEASURES: The main outcome measures were the incidences of SARS-CoV-2 infection in migrant workers and in the general population, as determined by the detection of neutralizing antibodies against SARS-CoV-2, and adjusting for assay sensitivity and specificity using a Bayesian modeling framework. RESULTS: No evidence of community SARS-CoV-2 exposure was found in Singapore prior to September 2019. It was estimated that < 2 per 1000 adult residents in the community were infected with SARS-CoV-2 in 2020 (cumulative seroprevalence: 0.16%; 95% CrI: 0.008-0.72%). Comparison with comprehensive national case notification data suggested that around 1 in 4 infections in the general population were associated with symptoms. In contrast, in the migrant worker cohort, almost two-thirds had been infected by July 2020 (cumulative seroprevalence: 63.8%; 95% CrI: 57.9-70.3%); no symptoms were reported in almost all of these infections. CONCLUSIONS AND RELEVANCE: Our findings demonstrate that SARS-CoV-2 suppression is possible with strict and rapid implementation of border restrictions, case isolation, contact tracing, quarantining, and social-distancing measures. However, the risk of large-scale epidemics in densely populated environments requires specific consideration in preparedness planning. Prioritization of these settings in vaccination strategies should minimize the risk of future resurgences and potential spillover of transmission to the wider community.

Highly functional virus-specific cellular immune response in asymptomatic SARS-CoV-2 infection.

The efficacy of virus-specific T cells in clearing pathogens involves a fine balance between antiviral and inflammatory features. SARS-CoV-2-specific T cells in individuals who clear SARS-CoV-2 without symptoms could reveal nonpathological yet protective characteristics. We longitudinally studied SARS-CoV-2-specific T cells in a cohort of asymptomatic (n = 85) and symptomatic (n = 75) COVID-19 patients after seroconversion. We quantified T cells reactive to structural proteins (M, NP, and Spike) using ELISpot and cytokine secretion in whole blood. Frequencies of SARS-CoV-2-specific T cells were similar between asymptomatic and symptomatic individuals, but the former showed an increased IFN-γ and IL-2 production. This was associated with a proportional secretion of IL-10 and proinflammatory cytokines (IL-6, TNF-α, and IL-1ß) only in asymptomatic infection, while a disproportionate secretion of inflammatory cytokines was triggered by SARS-CoV-2-specific T cell activation in symptomatic individuals. Thus, asymptomatic SARS-CoV-2-infected individuals are not characterized by weak antiviral immunity; on the contrary, they mount a highly functional virus-specific cellular immune response.

Prevalence and risk of acquisition of methicillin-resistant Staphylococcus aureus among households: A systematic review.

OBJECTIVE: Many studies have reported methicillin-resistant Staphylococcus aureus (MRSA) transmission from patients infected or colonized with MRSA to their household contacts, but the importance of household transmission for persistence of MRSA in the community and reintroduction into healthcare settings is not well understood. METHODS: This review was performed to evaluate evidence on (1) MRSA prevalence, (2) MRSA contact positivity, and (3) MRSA carriage duration in household contacts of MRSA-positive individuals. The MEDLINE and Embase databases were searched covering the period from January 1, 1960 to November 15, 2019 for studies with data on these outcomes. A random-effects model meta-analysis was conducted with included studies to calculate pooled prevalence ratios. RESULTS: A total 22 relevant articles were included. The meta-analysis showed that the pooled prevalence of MRSA among culture-positive MRSA household contacts was 25.0% (95% confidence interval 20.0-30.0%). A subset of studies with adequate comparison groups reported higher colonization prevalence among household contacts of MRSA-positive individuals compared with household contacts of MRSA-negative individuals. MRSA contact positivity varied between 19.0% and 33.0%, but variation in sampling frequency and follow-up duration made between-study comparisons challenging. CONCLUSIONS: Substantial MRSA transmission occurs in household settings. Improved understanding of household transmission dynamics and the relationship between transmission in healthcare and household settings will be critical to inform improved strategies to control MRSA.

The epidemiology and transmission of methicillin-resistant Staphylococcus aureus in the community in Singapore: study protocol for a longitudinal household study.

BACKGROUND/AIM: Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most common multidrug-resistant organisms in healthcare settings worldwide, but little is known about MRSA transmission outside of acute healthcare settings especially in Asia. We describe the methods for a prospective longitudinal study of MRSA prevalence and transmission. METHODS: MRSA-colonized individuals were identified from MRSA admission screening at two tertiary hospitals and recruited together with their household contacts. Participants submitted self-collected nasal, axilla and groin (NAG) swabs by mail for MRSA culture at baseline and monthly thereafter for 6 months. A comparison group of households of MRSA-negative patients provided swab samples at one time point. In a validation sub-study, separate swabs from each site were collected from randomly selected individuals, to compare MRSA detection rates between swab sites, and between samples collected by participants versus those collected by trained research staff. Information on each participant's demographic information, medical status and medical history, past healthcare facilities usage and contacts, and personal interactions with others were collected using a self-administered questionnaire. DISCUSSION/CONCLUSION: Understanding the dynamics of MRSA persistence and transmission in the community is crucial to devising and evaluating successful MRSA control strategies. Close contact with MRSA colonized patients may to be important for MRSA persistence in the community; evidence from this study on the extent of community MRSA could inform the development of household- or community-based interventions to reduce MRSA colonization of close contacts and subsequent re-introduction of MRSA into healthcare settings. Analysis of longitudinal data using whole-genome sequencing will yield further information regarding MRSA transmission within households, with significant implications for MRSA infection control outside acute hospital settings.

Trends in new species discovery of Orthoptera (Insecta) from Southeast Asia.

The orthopterans are diverse insects and play important roles in the ecosystem as well as having "love-hate relationship" with humans. Documentation of diversity in Southeast Asia has long history but remains incomplete. Using information of type specimens and Geographic Information System (GIS) techniques, we investigated the following questions on new species discovery for the region, specifically: (1) How are new species discoveries of orthopterans distributed in Southeast Asia? (2) How have new species discoveries changed with time? (3) How do new species discoveries relate to the countries of the type depositories? We found that new species discoveries, relative to sampling, are fragmentary in Southeast Asia and changes with different time periods. We also find type depositories tightly linked to the human (colonial) history of Southeast Asian countries. We provide some recommendations and hope that this can help to accelerate the study of orthopteran diversity in the region.

Socioeconomic status and fertility intentions among Chinese women with one child.

There has been a lack of socioeconomic status (SES) disparity analysis on women in China with only one child, the family planning target population. In 2008, the National Research Institute for Family Planning of China conducted a study investigating the relationship between SES and fertility intentions among 17,093 women in China who already had one child. A questionnaire was used to collect information on SES and fertility intentions, and logistic regression models were used to estimate the odds ratios and 95% CIs of fertility intentions according to SES. Compared with female farmers, women in other occupations intended to have fewer children (p < 0.05). Additionally, compared with women with low educational level (illiterate/primary), women with secondary and postsecondary education intended to have fewer children (p < 0.05) (OR = 0.70; 95% CI: 0.61-0.81 and OR = 0.56; 95% CI 0.47-0.66). A mother's education level was significantly and negatively associated with fertility intentions after adjustment for potential confounders (p < 0.05). Among Chinese women who had one child, the women with higher SES (e.g. higher educational level) had lower fertility intentions. There is an SES disparity in the fertility intention among Chinese women who already have one child. China's policy-makers should consider increasing high SES women's fertility intention.

Poor sleep quality associated with obesity in men.

OBJECTIVE: The objective of this study is to examine the association between sleep quality and obesity status. METHODS: A cross-sectional study of 3225 Chinese participants aged 18 to 65 years was conducted in Beijing in 2007. Body mass index (BMI) was classified according to the Working Group on Obesity in China, and sleep quality was assessed by the modified Pittsburg Sleep Quality Index questionnaire. Logistic regression models were applied to estimate the odds ratios (OR) and 95 % CIs of obesity by sleep quality adjusted for potential confounders. Two sets of potential confounders were used in the adjusted models. Model 1 was adjusted for sex and age. Model 2 was further adjusted for education level, occupation, marriage status, smoking, alcohol consumption, body pain, and health status. RESULTS: Poor sleep quality was significantly negatively associated with overweight/obesity in men but not in women. Additional adjustment for education level, occupation, marriage status, smoking, alcohol consumption, body pain, and health status did not attenuate the association (OR = 1.41 with 95 % CI 1.03-1.93; P < 0.05) among men. The adjusted OR per sleep quality score hour was 1.07 (1.01-1.14) for overweight/obesity, suggesting that for one score increase in sleep quality, obesity/overweight risk increased by 7 % in men. CONCLUSION: Sleep quality was negatively associated with overweight/obesity in Chinese men but not in women.

Season of birth, sex and sleep timing preferences.

OBJECTIVE: To evaluate whether the season of birth and sex are associated with preferences for bedtime among Chinese adults. METHODS: A national population-based study on sleep preferences was conducted among Chinese in 2008. A questionnaire was used to collect information on the sleep time of Chinese adults. Analysis of covariance was used to examine the relationship between season of birth and preferences for bedtime. Two sets of potential confounders were used in the adjusted models. Model 1 adjusted for age. Model 2 additionally adjusted for area, occupation, education level, smoking, and drinking. PARTICIPANTS AND MEASUREMENTS: The questionnaire was administered to a sample of 3959 Chinese adults. RESULTS: Men had a higher delayed mean sleep onset and offset time (22:38 and 6:32) than women (22:18 and 6:25). Men also slept for a shorter duration compared to women (7 h 54 min vs. 8 h 7 min). Women born in fall had the latest sleep onset time sleep offset time (22:23/6:30), compared to their counterparts born in winter. These associations were attenuated by additional adjustments of more confounders. CONCLUSIONS: There were significant differences in sleep timing preferences between men and women. Season of birth was not associated with sleep timing in Chinese adults.

Cluster of human infections with avian influenza A (H7N9) cases: a temporal and spatial analysis.

OBJECTIVES: This study aims to describe the spatial and temporal characteristics of human infections with H7N9 virus in China using data from February 2013 to March 2014 from the websites of every province's Population and Family Planning Commission. METHODS: A human infection with H7N9 virus dataset was summarized by county to analyze its spatial clustering, and by date of illness onset to analyze its space-time clustering using the ESRI® Geographic Information System (GIS) software ArcMap™ 10.1 and SatScan. RESULTS: Based on active surveillance data, the distribution map of H7N9 cases shows that compared to the rest of China, the areas from near the Yangtze River delta (YRD) to farther south around the Pearl River delta (PRD) had the highest densities of H7N9 cases. The case data shows a strong space-time clustering in the areas on and near the YRD from 26 March to 18 April 2013 and a weak space-time clustering only in the areas on and near the PRD between 3 and 4 February 2014. However, for the rest of the study period, H7N9 cases were spatial-temporally randomly distributed. CONCLUSIONS: Our results suggested that the spatial-temporal clustering of H7N9 in China between 2013 and 2014 is fundamentally different.