PDF(Pubmed)
Abstract：
BACKGROUND: China experienced an overwhelming COVID-19 pandemic from middle December 2022 to middle January 2023 after lifting the zero-COVID-19 policy on December 7, 2022. However, the infection rate was less studied. We aimed to investigate the SARS-CoV-2 infection rate in children shortly after discontinuation of the zero-COVID-19 policy.
METHODS: From February 20 to April 10, 2023, we included 393 children aged 8 months to less than 3 years who did not receive COVID-19 vaccination and 114 children aged 3 to 6 years who received inactivated COVID-19 vaccines based on the convenience sampling in this cross-sectional study. 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 (Shenzhen YHLO Biotech, China).
RESULTS: Of the 393 unvaccinated children (1.5 ± 0.6 years; 52.2% boys), 369 (93.9%) were anti-N/S1 IgG positive. Of the 114 vaccinated children (5.3 ± 0.9 years; 48.2% boys), 112 (98.2%) were anti-N/S1 IgG positive. None of the unvaccinated or vaccinated children was anti-N/S1 IgM positive. The median IgG antibody titers in vaccinated children (344.91 AU/mL) were significantly higher than that in unvaccinated children (42.80 AU/mL) (P < 0.0001). The positive rates and titers of anti-N/S1 IgG had no significant difference between boys and girls respectively.
CONCLUSIONS: Vast majority of children were infected with SARS-CoV-2 shortly after ending zero-COVID-19 policy in China. Whether these unvaccinated infected children should receive COVID-19 vaccine merits further investigation.
METHODS: From February 20 to April 10, 2023, we included 393 children aged 8 months to less than 3 years who did not receive COVID-19 vaccination and 114 children aged 3 to 6 years who received inactivated COVID-19 vaccines based on the convenience sampling in this cross-sectional study. 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 (Shenzhen YHLO Biotech, China).
RESULTS: Of the 393 unvaccinated children (1.5 ± 0.6 years; 52.2% boys), 369 (93.9%) were anti-N/S1 IgG positive. Of the 114 vaccinated children (5.3 ± 0.9 years; 48.2% boys), 112 (98.2%) were anti-N/S1 IgG positive. None of the unvaccinated or vaccinated children was anti-N/S1 IgM positive. The median IgG antibody titers in vaccinated children (344.91 AU/mL) were significantly higher than that in unvaccinated children (42.80 AU/mL) (P < 0.0001). The positive rates and titers of anti-N/S1 IgG had no significant difference between boys and girls respectively.
CONCLUSIONS: Vast majority of children were infected with SARS-CoV-2 shortly after ending zero-COVID-19 policy in China. Whether these unvaccinated infected children should receive COVID-19 vaccine merits further investigation.
摘要：
背景：在2022年12月7日取消零COVID-19政策后，中国从2022年12月中旬到2023年1月中旬经历了压倒性的COVID-19大流行。然而,感染率研究较少。我们旨在调查零COVID-19政策终止后不久儿童的SARS-CoV-2感染率。
方法：从2023年2月20日至4月10日，我们纳入了393名8个月至3岁未接种COVID-19疫苗的儿童和114名3至6岁的儿童，根据本横断面研究的便利抽样，接种了灭活COVID-19疫苗。用商业试剂盒（深圳YHLOBiotech，中国）。
结果：在393名未接种疫苗的儿童中（1.5±0.6岁；52.2％的男孩），369（93.9%）为抗N/S1IgG阳性。在114名接种疫苗的儿童中（5.3±0.9岁；48.2%的男孩），112（98.2%）为抗N/S1IgG阳性。未接种或接种疫苗的儿童均未出现抗N/S1IgM阳性。接种儿童IgG抗体滴度中位数(344.91AU/mL)明显高于未接种儿童(42.80AU/mL)(P<0.0001)。男孩和女孩之间的抗N/S1IgG阳性率和滴度分别没有显着差异。
结论：在中国结束零COVID-19政策后不久，绝大多数儿童感染了SARS-CoV-2。这些未接种疫苗的感染儿童是否应该接种COVID-19疫苗值得进一步调查。
方法：从2023年2月20日至4月10日，我们纳入了393名8个月至3岁未接种COVID-19疫苗的儿童和114名3至6岁的儿童，根据本横断面研究的便利抽样，接种了灭活COVID-19疫苗。用商业试剂盒（深圳YHLOBiotech，中国）。
结果：在393名未接种疫苗的儿童中（1.5±0.6岁；52.2％的男孩），369（93.9%）为抗N/S1IgG阳性。在114名接种疫苗的儿童中（5.3±0.9岁；48.2%的男孩），112（98.2%）为抗N/S1IgG阳性。未接种或接种疫苗的儿童均未出现抗N/S1IgM阳性。接种儿童IgG抗体滴度中位数(344.91AU/mL)明显高于未接种儿童(42.80AU/mL)(P<0.0001)。男孩和女孩之间的抗N/S1IgG阳性率和滴度分别没有显着差异。
结论：在中国结束零COVID-19政策后不久，绝大多数儿童感染了SARS-CoV-2。这些未接种疫苗的感染儿童是否应该接种COVID-19疫苗值得进一步调查。
