本研究旨在通过病毒学确认评估两种剂量的CoronaVac预防SARS-CoV-2症状性疾病的有效性。以及预防COVID-19中度和重度病例。使用测试阴性不匹配的病例对照设计,其中疑似COVID-19的患者(至少出现以下两种症状:发烧,发冷,喉咙痛,头痛,咳嗽,流鼻涕,嗅觉或味觉障碍)与病毒学确认,和对照组是SARS-CoV-2试验阴性的那些。至于曝光,参与者被归类为未接种疫苗,或接种完整的时间表。2021年3月至11月,在圣保罗州的两个城市发现了疑似COVID-19病例,巴西。所有参与者在注册前签署了知情同意书。RT-PCR结果和疫苗接种数据从当地监测系统获得。最多拨打了两个电话,以获取有关案件结果的信息。共有2981名潜在参与者接受了资格筛选,其中包括2163个,493例,1670例控制。疫苗接种,年龄,报告在症状发作前14天内与疑似或确诊病例接触,教育水平是与结果独立相关的变量。有症状的COVID-19(AVE)的调整疫苗有效率为39.0%(95%CI6.0-60.0%)。预防中重度疾病的AVE为91.0%(95%CI76.0-97.0%)。我们的结果受到Gamma变体减弱的影响,在2021年的中期,其次是疫苗接种覆盖率的增加,下半年病例数有所下降。这项研究证明了CoronaVac在预防中度/重度COVID-19病例方面的高度有效性。
The present study aimed to evaluate the effectiveness of two doses of CoronaVac in preventing SARS-CoV-2 symptomatic disease with virological confirmation, as well as in the prevention of COVID-19 moderate and severe cases. A test-negative unmatched
case-control design was used, in which cases were patients with suspected COVID-19 (presenting at least two of the following symptoms: fever, chills, sore throat, headache, cough, runny nose, olfactory or taste disorders) with virological confirmation, and controls were those whose SARS-CoV-2 test was negative. As for exposure, participants were classified as unvaccinated, or vaccinated with a complete schedule. Suspected COVID-19 cases were identified from March to November 2021, in two cities located in the State of São Paulo, Brazil. All participants signed the Informed Consent Form before enrollment. RT-PCR results and vaccination data were obtained from the local surveillance systems. Up to two phone calls were made to obtain information on the outcome of the cases. A total of 2981 potential participants were screened for eligibility, of which 2163 were included, being 493 cases and 1670 controls. Vaccination, age, the reported contact with a COVID-19 suspected or confirmed
case in the 14 days before symptoms onset, and the educational level were the variables independently associated with the outcome. The adjusted vaccine effectiveness for symptomatic COVID-19 (AVE) was 39.0 % (95 % CI 6.0-60.0 %). The AVE in the prevention of moderate and severe disease was 91.0 % (95 % CI 76.0-97.0 %). Our results were influenced by the waning of the Gamma variant, in the second trimester of 2021, followed by the increase in vaccination coverage, and a drop in the number of cases in the second half of the year. The study demonstrated the high effectiveness of CoronaVac in preventing moderate/severe COVID-19 cases.