Centro Centroamericano de Población, Universidad de Costa Rica, San Pedro, Costa Rica.
JMIR Public Health Surveill. 2022 May 20;8(5):e35054. doi: 10.2196/35054.
The Costa Rican COVID-19 vaccination program has used Pfizer-BioNTech and Oxford-AstraZeneca vaccines. Real-world estimates of the effectiveness of these vaccines to prevent hospitalizations range from 90%-98% for two doses and from 70%-91% for a single dose. Almost all of these estimates predate the Delta variant.
The aim of this study is to estimate the dose-dependent effectiveness of COVID-19 vaccines to prevent severe illness in real-world conditions in Costa Rica, after the Delta variant became dominant.
This observational study is a secondary analysis of hospitalization prevalence. The sample is all 3.67 million adult residents living in Costa Rica by mid-2021. The study is based on public aggregated data of 5978 COVID-19-related hospital records from September 14, 2021, to October 20, 2021, and 6.1 million vaccination doses administered to determine hospitalization prevalence by dose-specific vaccination status. The intervention retrospectively evaluated is vaccination with Pfizer-BioNTech (78%) and Oxford-AstraZeneca (22%). The main outcome studied is being hospitalized.
Vaccine effectiveness against hospitalization (VEH) was estimated as 93.4% (95% CI 93.0-93.9) for complete vaccination and 76.7% (95% CI 75.0-78.3) for single-dose vaccination among adults of all ages. VEH was lower and more uncertain among older adults aged ≥58 years: 92% (95% CI 91%-93%) for those who had received full vaccination and 64% (95% CI 58%-69%) for those who had received partial vaccination. Single-dose VEH declined over time during the study period, especially in the older age group. Estimates were sensitive to possible errors in the population count used to determine the residual number of unvaccinated people when vaccine coverage is high.
The Costa Rican COVID-19 vaccination program that administered Pfizer-BioNTech and Oxford-AstraZeneca vaccines seems to be highly effective at preventing COVID-19-related hospitalization after the Delta variant became dominant. Even a single dose seems to provide some degree of protection, which is good news for people whose second dose of the Pfizer-BioNTech vaccine was postponed several weeks to more rapidly increase the number of people vaccinated with a first dose. Timely monitoring of vaccine effectiveness is important to detect eventual failures and motivate the public to get vaccinated by providing information regarding the effectiveness of the vaccines.
哥斯达黎加的 COVID-19 疫苗接种计划使用了辉瑞-生物技术公司和牛津-阿斯利康疫苗。这两种疫苗预防住院的真实世界有效性估计值在两剂接种时为 90%-98%，一剂接种时为 70%-91%。几乎所有这些估计值都早于德尔塔变异株。
本研究旨在估计在德尔塔变异株成为主导后，哥斯达黎加真实环境下 COVID-19 疫苗预防重症的剂量依赖性效果。
这是一项关于住院患病率的观察性研究，是对二次分析。样本是截至 2021 年中期居住在哥斯达黎加的 367 万成年居民。该研究基于 2021 年 9 月 14 日至 2021 年 10 月 20 日公共聚合数据中 5978 例与 COVID-19 相关的住院记录，以及 610 万剂疫苗接种剂量，以确定按剂量特异性疫苗接种状况的住院患病率。回顾性评估的干预措施是接种辉瑞-生物技术公司（78%）和牛津-阿斯利康（22%）疫苗。主要研究结果是住院治疗。
对于所有年龄段的成年人，完全接种疫苗的疫苗有效性（VEH）估计为 93.4%（95%置信区间 93.0-93.9），而单剂接种疫苗的 VEH 为 76.7%（95%置信区间 75.0-78.3）。≥58 岁的老年人中，VEH 较低且更不确定：完全接种疫苗的人群为 92%（95%置信区间 91%-93%），部分接种疫苗的人群为 64%（95%置信区间 58%-69%）。在研究期间，单剂 VEH 随时间下降，尤其是在老年人群中。估计值对高疫苗覆盖率时用于确定未接种人群剩余数量的人口计数中可能存在的错误很敏感。
哥斯达黎加 COVID-19 疫苗接种计划使用辉瑞-生物技术公司和牛津-阿斯利康疫苗，在德尔塔变异株成为主导后，似乎对预防 COVID-19 相关住院治疗非常有效。即使是一剂疫苗似乎也能提供一定程度的保护，这对那些第二剂辉瑞-生物技术公司疫苗被推迟数周以更快地增加第一剂疫苗接种人数的人来说是个好消息。及时监测疫苗的有效性对于发现疫苗失效很重要，并通过提供疫苗有效性的信息来激励公众接种疫苗。
