Hong Kong SAR has adopted universal masking, social distancing, testing of all symptomatic and high-risk groups for isolation of confirmed cases in healthcare facilities, and quarantine of contacts as epidemiological control measures without city lockdown or border closure. These measures successfully suppressed the community transmission of pre-Omicron SARS-CoV-2 variants or lineages during the first to the fourth wave. No nosocomial SARS-CoV-2 infection was documented among healthcare workers in the first 300 days. The strategy of COVID-19 containment was adopted to provide additional time to achieve population immunity by vaccination. The near-zero COVID-19 situation for about 8 months in 2021 did not enable adequate immunization of the eligible population. A combination of factors was identified, especially population complacency associated with the low local COVID-19 activity, together with vaccine hesitancy. The importation of the highly transmissible Omicron variant kickstarted the fifth wave of COVID-19, which could no longer be controlled by our initial measures. The explosive fifth wave, which was partially contributed by vertical airborne transmission in high-rise residential buildings, resulted in over one million cases of infection. In this review, we summarize the epidemiology of COVID-19 and the infection control and public health measures against the importation and dissemination of SARS-CoV-2 until day 1000.

Nonpharmaceutical interventions implemented during the COVID-19 pandemic (2020–2021) have provided a unique opportunity to understand their impact on the wholesale supply of antibiotics and incidences of infections represented by bacteremia due to common bacterial species in Hong Kong. The wholesale antibiotic supply data (surrogate indicator of antibiotic consumption) and notifications of scarlet fever, chickenpox, and tuberculosis collected by the Centre for Health Protection, and the data of blood cultures of patients admitted to public hospitals in Hong Kong collected by the Hospital Authority for the last 10 years, were tabulated and analyzed. A reduction in the wholesale supply of antibiotics was observed. This decrease coincided with a significant reduction in the incidence of community-onset bacteremia due to Streptococcus pyogenes, Streptococcus pneumoniae, Haemophilus influenzae, and Neisseria meningitidis, which are encapsulated bacteria with respiratory transmission potential. This reduction was sustained during two pandemic years (period 2: 2020–2021), compared with eight pre-pandemic years (period 1: 2012–2019). Although the mean number of patient admissions per year (1,704,079 vs. 1,702,484, p = 0.985) and blood culture requests per 1000 patient admissions (149.0 vs. 158.3, p = 0.132) were not significantly different between periods 1 and 2, a significant reduction in community-onset bacteremia due to encapsulated bacteria was observed in terms of the mean number of episodes per year (257 vs. 58, p < 0.001), episodes per 100,000 admissions (15.1 vs. 3.4, p < 0.001), and per 10,000 blood culture requests (10.1 vs. 2.1, p < 0.001), out of 17,037,598 episodes of patient admissions with 2,570,164 blood culture requests. Consistent with the findings of bacteremia, a reduction in case notification of scarlet fever and airborne infections, including tuberculosis and chickenpox, was also observed; however, there was no reduction in the incidence of hospital-onset bacteremia due to Staphylococcus aureus or Escherichia coli. Sustained implementation of non-pharmaceutical interventions against respiratory microbes may reduce the overall consumption of antibiotics, which may have a consequential impact on antimicrobial resistance. Rebound of conventional respiratory microbial infections is likely with the relaxation of these interventions.

Background/Objectives: Hand, foot and mouth disease (HFMD) caused by enterovirus 71 (EV71) may cause severe complications and death in children. It is also a common cause of outbreaks in the Asia-Pacific Region. Incidence among children 1 to <2 years was over 3000/100,000 population in China. A systematic review and meta-analysis was performed to review evidence on vaccine efficacy (VE), immunogenicity, and safety of two doses of EV71 vaccine in children. Methods: Randomized controlled trials (RCTs) comparing EV71 vaccine with placebo or with another EV71 vaccine in children and adolescents aged ≤18 years were searched on PubMed, Medline, Embase, CENTRAL, and CNKI (Chinese) in week 5 November 2024. The reference list of each study and the websites of vaccine manufacturers were also searched. The Cochrane Risk of Bias 2 tool (RoB2) was used to assess the risk of bias. VE, immunogenicity (including seropositive rate, seroconversion rate, geometric mean titer (GMT), Geometric Mean Fold Increase (GMFI)), and rate of adverse events were analyzed. Results: A total of 4199 articles were identified, and 25 studies were finally included. VE (%) against EV71 HFMD in children aged ≤5 years at 12 months was 94.8% (95%CI 87.2–97.9) for Sinovac and 90.9% (95%CI 70.4–97.2) for Wuhan Institute of Biological Products (WIBP), while the Chinese Academy of Medical Sciences (CAMS) reported 97.4% (95%CI 92.9–99.0) at 11 months. At 1 month after the second dose, 99.19% (95%CI 98.15–99.65) of children aged ≤5 years in the vaccine group were seropositive, and 96.30% (95%CI 92.71–98.17) achieved seroconversion. GMT at 1 month after the second dose in the vaccine group was 46.78 (95%CI 26.18–83.61) times that in the placebo group. GMFI at 1 month after the second dose in the vaccine group was 28.41 (95%CI 22.18–36.39) times that of the placebo group. The rate of serious adverse events (AEs) was lower in the vaccine group than the placebo group (1.23% (95%CI 0.58–2.69) vs. 1.34% (95%CI 0.58–3.07)) at 1 month after the second dose. There was no significant difference in other adverse events between the vaccine and placebo groups. Conclusions: EV71 vaccines were effective, immunogenic and safe. Areas with a high incidence of EV71 may consider introducing EV71 vaccines.