Incidence of SARS-CoV-2 infection in children shortly after ending zero-COVID-19 policy in China on December 7, 2022: a cross-sectional, multicenter, seroepidemiological study.

Background: China discontinued the zero-COVID-19 policy on December 7, 2022, and then COVID-19 surged mid-December 2022 through mid-January 2023. However, the actual incidence was unknown. This study aimed to estimate the incidence of SARS-CoV-2 infection in children shortly after ending the zero-COVID-19 policy. Methods: This multicenter cross-sectional study included 1,065 children aged 8 months to 12 years from seven hospitals at six regions across Jiangsu province, based on the convenience sampling, from February 10 to March 10, 2023. Group I comprised 324 children aged 8 months-2 years without COVID-19 vaccination, group II consisted of 338 preschool children aged 3-5 years with varied vaccination history, and group III contained 403 primary school children aged 6-12 years with mostly vaccinated. The COVID-19 vaccines were composed of inactivated SARS-CoV-2. In addition, 96 children's sera collected in 2014 were included as negative controls. IgG and IgM antibodies against nucleocapsid (N) and subunit 1 of spike (S1) of SARS-CoV-2 (anti-N/S1) were measured with commercial kits (YHLO Biotech, Shenzhen, China). Results: None of the 96 children (5.1 ± 3.5 years; 58.3% boys) in 2014 was positive for anti-N/S1 IgG or IgM. Of the 1,065 children (5.0 ± 3.5 years; 56.0% boys), 988 (92.8%) were anti-N/S1 IgG positive but none was anti-N/S1 IgM positive. The positive rate of anti-N/S1 IgG in Group I, II, and III was 90.4, 88.5, and 98.3%, respectively, with significantly higher in group III than in groups I and II (p < 0.0001). The median antibody titers in group III (381.61 AU/ml) were much higher than that in group I (38.34 AU/ml) and II (51.88 AU/ml; p < 0.0001). Conclusion: More than 90% children experienced SARS-CoV-2 infection shortly after ending zero-COVID-19 policy in China, much higher than estimated infections by other studies. The widespread SARS-CoV-2 infection in unvaccinated children should be influential on the policy of COVID-19 vaccination in children in the future.

Prevalence of antibody to hepatitis B surface antigen among qualified blood donors in Nanjing, China.

Universal infant hepatitis B vaccination has been implemented more than three decades. This study aimed to determine the prevalence of antibodies to hepatitis B surface antigen (anti-HBs) and to hepatitis B core antigen (anti-HBc) in qualified blood donors in Nanjing, China. Plasmas of 815 qualified blood donors, collected from February through May 2019, were measured for anti-HBs and anti-HBc by enzyme-linked immunosorbent assay. There were 449 (55.1%) male and 366 (44.9%) female blood donors, with a median age of 28.9 years (18-60). The seroprevalence of anti-HBs was 58.8%, with no significant difference in different genders and different age groups. The overall prevalence of anti-HBc was 7.0%, with an increasing trend with age, from 0% in 18-20 years old group to 17.9% in 51-60 years old group (χ2 = 46.7965, p < .0001). The prevalence of anti-HBc in donors born after the implementation of universal hepatitis B vaccination was significantly lower than that in donors born before (1.0% vs 15.5%; χ2 = 63.6033, p < .0001). Our data suggest that more than half of the blood donors in Nanjing are anti-HBs positive. Since a blood recipient usually receives more than one unit of red blood cells or plasma, passively acquired anti-HBs in blood recipients may neutralize hepatitis B virus potentially presented in blood donors with occult hepatitis B infection. In addition, the presence of anti-HBs and/or anti-HBc in blood donors may cause unique hepatitis B serological profile in blood recipients.

Risk Factors of Fatal Outcome of Hospitalized Patients with COVID-19.

BACKGROUND: Few studies reported the risk factors of fatal outcome of hospitalized patients with coronavirus disease 2019 (COVID-19). We aimed to identify the independent risk factors associated with fatal outcome of hospitalized COVID-19 patients. METHODS: The clinical data of 109 consecutive COVID-19 patients including 40 (36.7%) common cases and 69 (63.3%) severe cases were included and analyzed. RESULTS: Multivariate regression analysis indicated that platelets (PLT, OR, 0.988; 95% CI, 0.978-0.998; P=0.017) and C-reactive protein (CRP) (OR, 1.047; 95% CI, 1.026-1.068; P<0.001) levels were the independent risk factors of fatal outcome in COVID-19 patients. The optimal cut-off value of PLT counts for predicting fatal outcome was 161x109/L with the area under receiver operating characteristic curve (AUROC) of 0.824 (95% CI, 0.739-0.890). The optimal cut-off value of CRP for the prediction of fatal outcome was 46.2 mg/L with the AUROC of 0.954 (95% CI, 0.896-0.985). The CRP levels had higher predictive values for fatal outcome than PLT (P=0.016). The cumulative survival rate was significantly higher in patients with PLT>161x109/L compared with patients with PLT≤161x109/L (89.4% vs. 12.5%, log-rank test X2=72.17; P<0.001). Survival rate of COVID-19 patients was prominently higher in CRP≤46.2 mg/L patients compared with patients with CRP>46.2 mg/L (95.9% vs. 22.9%, log-rank test X2=77.85; P<0.001). CONCLUSIONS: PLT counts and CRP levels could predict fatal outcome of hospitalized COVID-19 patients with relatively high accuracy.