Introduction Transmission of COVID-19 within families and close contacts accounts for the majority of epidemic growth. Community mask wearing, hand washing and social distancing are thought to be effective but there is little evidence to inform or support community members on COVID-19 risk reduction within families. Methods A retrospective cohort study of 335 people in 124 families and with at least one laboratory confirmed COVID-19 case was conducted from 28 February to 27 March 2020, in Beijing, China. The outcome of interest was secondary transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) within the family. Characteristics and practices of primary cases, of well family contacts and household hygiene practices were analysed as predictors of secondary transmission. Results The secondary attack rate in families was 23.0% (77/335). Face mask use by the primary case and family contacts before the primary case developed symptoms was 79% effective in reducing transmission (OR=0.21, 95% CI 0.06 to 0.79). Daily use of chlorine or ethanol based disinfectant in households was 77% effective (OR=0.23, 95% CI 0.07 to 0.84). Wearing a mask after illness onset of the primary case was not significantly protective. The risk of household transmission was 18 times higher with frequent daily close contact with the primary case (OR=18.26, 95% CI 3.93 to 84.79), and four times higher if the primary case had diarrhoea (OR=4.10, 95% CI 1.08 to 15.60). Household crowding was not significant. Conclusion The study confirms the highest risk of transmission prior to symptom onset, and provides the first evidence of the effectiveness of mask use, disinfection and social distancing in preventing COVID-19. We also found evidence of faecal transmission. This can inform guidelines for community prevention in settings of intense COVID-19 epidemics.

Background: With the spread of SARS-CoV-2 worldwide, understanding the basic epidemiological parameter values of COVID-19 from real-world data in mega-cities is essential for disease prevention and control.Methods: To investigate the epidemiological parameters in SARS-CoV-2 infected cases in Beijing, we studied all confirmed cases and close contacts in Beijing from Jan 1st to Apr 3rd 2020. The epidemiological and virological characteristics of SARS-CoV-2 were analyzed.Results: A total of 602 cases were positive for SARS-CoV-2, including 585 confirmed patients and 17 asymptomatic infections. The imported cases were mainly from Wuhan initially and then from abroad. Among 585 confirmed case-patients, the median age was 39 years old. The mean incubation period was 6.3 days. The secondary attack rate among households was higher than social contacts (15.6 vs 4.6%). The secondary attack rate of healthcare workers (HCWs) was higher than non-HCWs’ (7.3 vs 4.2%). The basic reproduction number was 2.0, and the average serial interval was 7.6 days. No significant genetic variant was identified.Conclusions: The transmissibility of SARS-CoV-2 was relatively high, especially among households and from HCWs, which draws specific public health attention. So far, no evidence of widespread circulation of SARS-CoV-2 in communities in Beijing was found.

In 2023, through an ongoing respiratory pathogen surveillance system, we observed from mid-September onwards, an increase of respiratory illness among children aged ≤ 15 years presenting at hospital outpatient clinics in Beijing, China. Data indicated that illness was caused by multiple pathogens, predominantly Mycoplasma pneumoniae. Seasonality, periodicity and high prevalence of resistance to macrolide (30 of 30 strains sequenced with the A2063G mutation) were important characteristics of the M. pneumoniae epidemic, which resulted in a rise in consultations at specialised paediatric hospitals.

Objectives The present study aimed to estimate the influenza vaccination coverage rate in Beijing, China, and identify its determinants in older and younger adults. Methods A survey was conducted among Chinese adults using a self-administered, anonymous questionnaire in May–June 2015. The main outcome was seasonal influenza vaccination uptake. Multivariate logistic regression models were performed to identify factors associated with uptake. Results A total of 7106 participants completed the questionnaire. The overall coverage rate was 20.6% (95% CI 19.7% to 21.5%) in the 2014/2015 influenza season. Lower education (older adults: OR 1.6; 95% CI 1.2 to 2.1; younger adults: OR 1.9; 95% CI 1.4 to 2.6), having a chronic illness (older adults: OR 1.9; 95% CI 1.5 to 2.4; younger adults: OR 1.4; 95% CI 1.2 to 1.7) and recommendations from healthcare workers (older adults: OR 5.4; 95% CI 3.9 to 7.4; younger adults: OR 4.5; 95% CI 3.7 to 5.4) were positively associated with uptake; perceived side effects of vaccination had a negative impact (older adults: OR 0.6; 95% CI 0.4 to 0.7; younger adults: OR 0.8; 95% CI 0.7 to 1.0). Perceived susceptibility to influenza (OR 1.5; 95% CI 1.2 to 2.0) and awareness of the free influenza vaccine policy (OR 1.9; 95% CI 1.2 to 2.9) were only associated with vaccine uptake in older adults, while perceived effectiveness of vaccination (OR 2.2; 95% CI 1.7 to 2.8) was only a predictor for younger adults. Older adults were more likely to receive recommendations from healthcare professionals and perceive the severity of seasonal influenza, and less likely to worry about side effects of vaccination. Conclusion The influenza vaccination coverage rate was relatively low in Beijing. Apart from free vaccinations for older adults, age disparity in the rate between older and younger adults (48.7% vs 16.0%) may be explained by differing professional recommendations and public perceptions. Vaccination campaigns targeting increasing professional recommendations and public perceptions should be implemented in the coming years.

Background: In 2009, a novel influenza A(H1N1)pdm09 virus was detected and caused influenza pandemic. It is important to identify the risk factors for severe outcomes. However, inconsistent results regarding the effect of obesity were reported in previous studies. Methods: We conducted a systematic review to assess the association between obesity and poor prognosis for laboratory-confirmed A(H1N1)pdm09 influenza. We searched three English databases and three Chinese databases for relevant studies from April 2009 to October 2015: PubMed, the Cochrane library, Embase, CNKI, CBM, and Wanfang. Two investigators independently identified eligible articles, assessed quality using NOS, and extracted data. We performed meta-analyses and meta-regressions to estimate the association between weight and poor prognosis for influenza A(H1N1)pdm09 infection, when data were available. Results: We identified 22 articles enrolling 25,189 laboratory confirmed patients. The pooled estimates indicated obesity significantly increased the risk of fatal and critical complications of influenza A(H1N1)pdm09 infection (for fatal, OR = 1.81, 95% CI: 1.23−2.65; for critical complications, OR = 1.67, 95% CI: 1.13−2.47). However, we found significant interaction between early antiviral treatment and obesity (β = −0.28). After adjustment for early antiviral treatment, relationship between obesity and poor outcomes disappeared (OR = 1.14, 95% CI: 0.94−1.39). Conclusions: The results of the meta-analyses showed obesity significantly increased the risk of death, critical complications, and severe complications for influenza A(H1N1)pdm09 infection, especially among high-quality studies and in Asia region. Importantly, the result from our meta-regression indicated that the conclusion should be interpreted with caution, because early antiviral treatment might be a key confounding factor.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has lasted for two years and caused millions of infections and deaths in humans. Although the origin of SARS-CoV-2 infection in humans remains unknown, infection in animals has been frequently reported in varieties of animals all over the world. Both experimental and natural infections of SARS-CoV-2 in different animal species provide useful information on viral host range and pathogenicity. As the pandemic continues to evolve, SARS-CoV-2 infection in animals will be expanding. In this review, we summarized SARS-CoV-2 testing and infection in animals as well as SARS-CoV-2 strains and transmission in animals. Current data showed that at least 18 different animal species tested positive for SARS-CoV-2. These 18 animal species belong to pet, captive, farmed, and wild animals. Fifteen of the eighteen animal species were known to be positive for the Delta variant and ten animal species were infected with two different types of variants. Human-to-animal, animal-to-animal, and animal-to-human transmission events were suggested in different outbreaks involved in animal infection with SARS-CoV-2. Continued testing, immunization, and surveillance are warranted.