■由于SARS-CoV-2Omicron变体引起的儿科COVID-19发病率增加,引起了人们对现有疫苗有效性的担忧。尚未研究SOBERANA-02-Plus疫苗接种方案针对该变体提供的保护。我们旨在评估该方案对儿童症状性Omicron感染和严重疾病的有效性。
■2021年9月,古巴采用异源SOBERANA-02-Plus方案实施了大规模儿科免疫:2剂量的SOBERANA-02缀合,然后是异源SOBERANA-Plus剂量。到12月,在Omicron爆发之前,95.4%的2-18岁儿童已完全免疫。在整个Omicron波期间,我们进行了一项全国性的疫苗接种后纵向病例-人群研究,以评估SOBERANA-02-Plus方案对既往无SARS-CoV-2感染的儿童的症状性感染和严重疾病的真实世界有效性.COVID-19病例的识别依赖于一线服务的监测,将临床嫌疑人转诊到儿科医院,在那里他们根据阳性RT-PCR检测被诊断。我们将发病率比率(IRR)定义为免疫接种年龄组/免疫接种1岁,并将疫苗有效性计算为VE=(1-IRR)*100%。24个月的年龄是“有资格接种疫苗”的截止日期,我们使用回归不连续方法,通过对比所有未接种疫苗的1岁儿童和接种疫苗的2岁儿童的发生率来评估有效性.从描述性角度报告接种疫苗3-11岁的估计。
■我们包括1,098,817名2-11岁完全接种疫苗的儿童和98,342名1岁未接种疫苗的儿童。在24周的Omicron波期间,接种疫苗组中有7003/26,241,176人周有症状的COVID-19感染(2岁/105人周38.2例,3-11岁/105人周25.5例),未接种疫苗组中有3577/2,312,273例(每105人周154.7例).在2岁儿童中,观察到的针对症状性感染的总体疫苗有效性为75.3%(95%CI,73.5-77.0%),3-11岁儿童占83.5%(95%CI,82.8-84.2%)。在OmicronBA.1期间比在OmicronBA.2变体循环期间低一些,这发生在疫苗接种运动结束后的1-3和4-6个月。在各个年龄组中,对严重症状疾病的有效性分别为100.0%(95%CI未估计)和94.6%(95%CI,82.0-98.6%)。没有观察到儿童死于COVID-19。
■使用SOBERANA-02-Plus方案对2-11岁的儿童进行免疫接种,可对Omicron变种引起的症状和严重疾病提供强有力的保护,在疫苗接种后的6个月随访期间持续。我们的结果与以前的真实世界儿童疫苗有效性研究中的观察结果相反,这可能是由基于结合蛋白的疫苗诱导的免疫类型和使用的疫苗接种策略来解释的。
■国家科学技术基金(FONCI-CITMA-Cuba)。
UNASSIGNED: Increased pediatric COVID-19 occurrence due to the SARS-CoV-2 Omicron variant has raised concerns about the
effectiveness of existing vaccines. The protection provided by the SOBERANA-02-Plus vaccination scheme against this variant has not yet been studied. We aimed to evaluate the scheme\'s
effectiveness against symptomatic Omicron infection and severe disease in children.
UNASSIGNED: In September 2021, Cuba implemented a mass pediatric immunization with the heterologous SOBERANA-02-Plus scheme: 2 doses of conjugated SOBERANA-02 followed by a heterologous SOBERANA-Plus dose. By December, before the Omicron outbreak, 95.4% of 2-18 years-old had been fully immunized. During the entire Omicron wave, we conducted a nationwide longitudinal post-vaccination
case-population study to evaluate the real-world effectiveness of the SOBERANA-02-Plus scheme against symptomatic infection and severe disease in children without previous SARS-CoV-2 infection. The identification of COVID-19 cases relied on surveillance through first line services, which refer clinical suspects to pediatric hospitals where they are diagnosed based on a positive RT-PCR test. We defined the Incidence Rate ratio (IRR) as IRvaccinated age group/IRunvaccinated 1-year-old and calculated vaccine effectiveness as VE = (1-IRR)∗100%. 24 months of age being the \'eligible for vaccination\' cut-off, we used a regression discontinuity approach to estimate effectiveness by contrasting incidence in all unvaccinated 1-year-old versus vaccinated 2-years-old. Estimates in the vaccinated 3-11 years-old are reported from a descriptive perspective.
UNASSIGNED: We included 1,098,817 fully vaccinated 2-11 years-old and 98,342 not vaccinated 1-year-old children. During the 24-week Omicron wave, there were 7003/26,241,176 person-weeks symptomatic COVID-19 infections in the vaccinated group (38.2 per 105 person-weeks in 2-years-old and 25.5 per 105 person-weeks in 3-11 years-old) against 3577/2,312,273 (154.7 per 105 person-weeks) in the unvaccinated group. The observed overall vaccine
effectiveness against symptomatic infection was 75.3% (95% CI, 73.5-77.0%) in 2-years-old children, and 83.5% (95% CI, 82.8-84.2%) in 3-11 years-old. It was somewhat lower during Omicron BA.1 then during Omicron BA.2 variant circulation, which took place 1-3 and 4-6 months after the end of the vaccination campaign. The
effectiveness against severe symptomatic disease was 100.0% (95% CI not estimated) and 94.6% (95% CI, 82.0-98.6%) in the respective age groups. No child death from COVID-19 was observed.
UNASSIGNED: Immunization of 2-11 years-old with the SOBERANA-02-Plus scheme provided strong protection against symptomatic and severe disease caused by the Omicron variant, which was sustained during the six months post-vaccination follow-up. Our results contrast with the observations in previous real-world vaccine effectiveness studies in children, which might be explained by the type of immunity a conjugated protein-based vaccine induces and the vaccination strategy used.
UNASSIGNED: National Fund for Science and Technology (FONCI-CITMA-Cuba).