Departamento de Física, Universidade Federal do Ceará, Fortaleza, Ceará, Brazil; Secretaria Municipal de Saúde de Fortaleza (SMS-Fortaleza), Fortaleza, Ceará, Brazil.
Secretaria Municipal de Saúde de Fortaleza (SMS-Fortaleza), Fortaleza, Ceará, Brazil; Centro de Ciências da Saúde, Universidade de Fortaleza (UNIFOR), Fortaleza, Ceará, Brazil.
Vaccine. 2023 Sep 7;41(39):5742-5751. doi: 10.1016/j.vaccine.2023.07.065. Epub 2023 Aug 10.
Although CoronaVac was the only Covid-19 vaccine adopted in the first months of the Brazilian vaccination campaign, randomized clinical trials to evaluate its efficacy in elderly adults were limited. In this study, we use routinely collected surveillance and SARS-CoV-2 vaccination and testing data comprising the population of the fifth largest city of Brazil to evaluate the effectiveness of CoronaVac in adults 60+ years old against severe outcomes.
Using large observational databases on vaccination and surveillance data from the city of Fortaleza, Brazil, we defined a retrospective cohort including 324,302 eligible adults aged ≥60 years to evaluate the effectiveness of the CoronaVac vaccine. The cohort included individuals vaccinated between January 21, 2021, and August 31, 2021, who were matched with unvaccinated persons at the time of rollout following a 1:1 ratio according to baseline covariates of age, sex, and Human Development Index of the neighborhood of residence. Only Covid-19-related severe outcomes were included in the analysis: hospitalization, ICU admission, and death. Vaccine effectiveness for each outcome was calculated by using the risk ratio between the two groups, with the risk obtained by the Kaplan-Meier estimator.
We obtained 62,643 matched pairs for assessing the effectiveness of the two-dose regimen of CoronaVac. The demographic profile of the matched population was statistically representative of the population of Fortaleza. Using the cumulative incidence as the risk associated with each group, starting at day 14 since the receipt of the second dose, we found an 82.3 % (95 % CI 66.3-93.9) effectiveness against Covid-19-related death, 68.4 % (95 % CI 42.3-86.4) against ICU admission, and 55.8 % (95 % CI 42.7-68.3) against hospital admission.
Our results show that, despite critical delays in vaccine delivery and limited evidence in efficacy trial estimates, CoronaVac contributed to preventing deaths and severe morbidity due to Covid-19 in elderly adults.
尽管科兴疫苗是巴西疫苗接种计划最初几个月唯一采用的新冠疫苗，但评估其在老年人中疗效的随机临床试验却很有限。在这项研究中，我们使用巴西第五大城市常规收集的监测和 SARS-CoV-2 疫苗接种和检测数据，评估科兴疫苗对 60 岁以上成年人的预防严重后果的有效性。
我们利用巴西福塔雷萨市的疫苗接种和监测大数据数据库，定义了一个回顾性队列，其中包括 324302 名符合条件的 60 岁及以上成年人，以评估科兴疫苗的有效性。该队列包括 2021 年 1 月 21 日至 2021 年 8 月 31 日接种疫苗的人群，根据居住地的年龄、性别和人类发展指数等基线协变量，按照 1:1 的比例与未接种人群进行匹配。仅将与新冠相关的严重结局纳入分析：住院、入住 ICU 和死亡。通过两组之间的风险比计算每种结局的疫苗有效性，风险通过 Kaplan-Meier 估计器获得。
我们获得了 62643 对评估两剂科兴疫苗有效性的匹配对。匹配人群的人口统计学特征在统计学上代表了福塔雷萨市的人群。使用从第二剂接种后第 14 天开始的累积发病率作为与每组相关的风险，我们发现科兴疫苗对与新冠相关的死亡的有效性为 82.3%（95%CI 66.3-93.9），对 ICU 入院的有效性为 68.4%（95%CI 42.3-86.4），对住院的有效性为 55.8%（95%CI 42.7-68.3）。
尽管疫苗接种存在严重延迟，且在疗效试验估计方面证据有限，但科兴疫苗对预防老年人因新冠导致的死亡和严重发病仍发挥了作用。
