Objective To estimate the effectiveness of a two dose vaccine schedule (mRNA-1273, BNT162b2, and BBIBP-CorV) against SARS-CoV-2 infection and covid-19 related death and short term waning of immunity in children (3-11 years old) and adolescents (12-17 years old) during periods of delta and omicron variant predominance in Argentina. Design Test negative, case-control study. Setting Database of the National Surveillance System and the Nominalized Federal Vaccination Registry of Argentina. Participants 844 460 c hildren and adolescents without previous SARS-CoV-2 infection eligible to receive primary vaccination schedule who were tested for SARS-CoV-2 by polymerase chain reaction or rapid antigen test from September 2021 to April 2022. After matching with their corresponding controls, 139 321 (60.3%) of 231 181 cases remained for analysis. Exposures Two dose mRNA-1273, BNT162b2, and BBIBP-CorV vaccination schedule. Main outcome measures SARS-CoV-2 infection and covid-19 related death. Conditional logistic regression was used to estimate the odds of SARS-CoV-2 infection among two dose vaccinated and unvaccinated participants. Vaccine effectiveness was estimated as (1–odds ratio)×100%. Results Estimated vaccine effectiveness against SARS-CoV-2 infection was 61.2% (95% confidence interval 56.4% to 65.5%) in children and 66.8% (63.9% to 69.5%) in adolescents during the delta dominant period and 15.9% (13.2% to 18.6%) and 26.0% (23.2% to 28.8%), respectively, when omicron was dominant. Vaccine effectiveness declined over time, especially during the omicron period, from 37.6% (34.2% to 40.8%) at 15-30 days after vaccination to 2.0% (1.8% to 5.6%) after ≥60 days in children and from 55.8% (52.4% to 59.0%) to 12.4% (8.6% to 16.1%) in adolescents. Vaccine effectiveness against death related to SARS-CoV-2 infection during omicron predominance was 66.9% (6.4% to 89.8%) in children and 97.6% (81.0% to 99.7%) in adolescents. Conclusions Vaccine effectiveness in preventing mortality remained high in children and adolescents regardless of the circulating variant. Vaccine effectiveness in preventing SARS-CoV-2 infection in the short term after vaccination was lower during omicron predominance and decreasing sharply over time. Trial registration National Registry of Health Research IS003720. The data that support the findings of this study will be available for researchers who provide a methodologically sound proposal after it is approved, on request from the corresponding author.

中文翻译：

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在 delta 和 omicron covid-19 变种占主导地位的情况下，mRNA-1273、BNT162b2 和 BBIBP-CorV 疫苗对阿根廷儿童感染和死亡的有效性：测试阴性、病例对照研究


目的 评估两剂疫苗方案（mRNA-1273、BNT162b2 和 BBIBP-CorV）对儿童（3-11 岁）SARS-CoV-2 感染和 covid-19 相关死亡以及短期免疫力下降的有效性) 和青少年 (12-17 岁) 在阿根廷 delta 和 omicron 变异占主导地位的时期。设计测试阴性，病例对照研究。设置阿根廷国家监测系统和名义联邦疫苗登记数据库。参与者 844 460 名既往未感染过 SARS-CoV-2 且符合初次疫苗接种计划的儿童和青少年，于 2021 年 9 月至 2022 年 4 月期间通过聚合酶链反应或快速抗原检测进行了 SARS-CoV-2 检测。对照，231 181 例中的 139 321 例（60.3%）仍有待分析。暴露 两剂 mRNA-1273、BNT162b2 和 BBIBP-CorV 疫苗接种计划。主要结果衡量 SARS-CoV-2 感染和 covid-19 相关死亡。使用条件逻辑回归来估计两剂疫苗接种和未接种疫苗的参与者感染 SARS-CoV-2 的几率。疫苗有效性估计为（1-优势比）×100%。结果 估计疫苗对 SARS-CoV-2 感染的有效性在儿童中为 61.2%（95% 置信区间为 56.4% 至 65.5%），在 Delta 显性期为青少年中为 66.8%（63.9% 至 69.5%），在青少年中为 15.9%（13.2%）。当 omicron 占主导地位时，分别为 18.6% 和 26.0%（23.2% 至 28.8%）。疫苗有效性随着时间的推移而下降，特别是在 omicron 期间，从接种后 15-30 天的 37.6%（34.2% 至 40.8%）下降到 ≥60 天后的 2.0%（1.8% 至 5.6%），儿童则从 55.8%（青少年中为 52.4% 至 59.0%）至 12.4%（8.6% 至 16.1%）。 在 omicron 占主导地位期间，疫苗对抗 SARS-CoV-2 感染相关死亡的有效性在儿童中为 66.9%（6.4% 至 89.8%），在青少年中为 97.6%（81.0% 至 99.7%）。结论 无论流行的变种如何，疫苗在预防儿童和青少年死亡方面的有效性仍然很高。在 omicron 占主导地位期间，疫苗接种后短期内预防 SARS-CoV-2 感染的有效性较低，并且随着时间的推移急剧下降。国家健康研究登记处试验注册 IS003720。应通讯作者的要求，在该研究获得批准后，提供方法论合理提案的研究人员将可以获得支持本研究结果的数据。