■中国于2022年12月7日终止了零COVID-19政策,然后COVID-19在2022年12月中旬飙升至2023年1月中旬。然而,实际发病率未知.这项研究旨在评估零COVID-19政策结束后不久儿童SARS-CoV-2感染的发生率。
■这项多中心横断面研究包括来自江苏省六个地区的七家医院的1,065名8个月至12岁的儿童,基于方便的抽样,从2月10日到2023年3月10日。第一组包括324名8个月至2岁未接种COVID-19疫苗的儿童,第二组由338名3-5岁有不同疫苗接种史的学龄前儿童组成,第三组包括403名6-12岁的小学生,主要接种疫苗。COVID-19疫苗由灭活的SARS-CoV-2组成。此外,2014年收集的96份儿童血清作为阴性对照。用商业试剂盒(YHLOBiotech,深圳,中国)。
■2014年的96名儿童(5.1±3.5岁;58.3%的男孩)中没有一个抗N/S1IgG或IgM阳性。在1,065名儿童中(5.0±3.5岁;56.0%的男孩),988(92.8%)为抗N/S1IgG阳性,但无一抗N/S1IgM阳性。Ⅰ组抗N/S1IgG阳性率,II,III分别为90.4、88.5和98.3%,分别,III组明显高于I组和II组(p<0.0001)。III组的中位抗体滴度(381.61AU/ml)远高于I组(38.34AU/ml)和II组(51.88AU/ml;p<0.0001)。
■在中国结束零-COVID-19政策后不久,超过90%的儿童经历了SARS-CoV-2感染,远高于其他研究估计的感染。未接种疫苗儿童中SARS-CoV-2的广泛感染将对未来儿童COVID-19疫苗接种政策产生影响。
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.
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).
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).
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.