Mahumud Rashidul Alam, Ali Mohammad Afshar, Kundu Satyajit, Rahman Md Ashfikur, Kamara Joseph Kihika, Renzaho Andre M N
NHMRC Clinical Trials Centre, Faculty of Medicine and Health, The University of Sydney, Camperdown, NSW 2006, Australia.
School of Business and Centre for Health Research, University of Southern Queensland, Toowoomba, QLD 4350, Australia.
Vaccines (Basel). 2022 Feb 11;10(2):277. doi: 10.3390/vaccines10020277.
The highly transmissible COVID-19 Delta variant (DV) has contributed to a surge in cases and exacerbated the worldwide public health crisis. Several COVID-19 vaccines play a significant role in a high degree of protection against the DV. The primary purpose of this meta-analysis is to estimate the pooled effectiveness of the COVID-19 vaccines against the DV in terms of risk ratio (RR) among fully vaccinated, compared to unvaccinated populations. We carried out a systematic review, with meta-analysis of original studies focused on COVID-19 vaccines effectiveness against a DV clinical perspective among fully COVID-19 vaccinated populations, compared to placebo (unvaccinated populations), published between 1 May 2021 and 30 September 2021. Eleven studies containing the data of 17.2 million participants were identified and included in our study. Pooled estimates of COVID-19 vaccines effectiveness (i.e., risk ratio, RR) against the DV with 95% confidence intervals were assessed using random-effect models. Publication bias was assessed using Egger's regression test and funnel plot to investigate potential sources of heterogeneity and identify any differences in study design. A total population of 17.2 million (17,200,341 people) were screened for the COVID-19 vaccines' effectiveness against the DV. We found that 61.13% of the study population were fully vaccinated with two doses of COVID-19 vaccines. The weighted pooled incidence of COVID-19 infection was more than double (20.07%) among the unvaccinated population, compared to the fully vaccinated population (8.16%). Overall, the effectiveness of the COVID-19 vaccine against the DV was 85% (RR = 0.15, 95% CI: 0.07-0.31). The effectiveness of COVID-19 vaccines varied slidably by study designs, 87% (RR = 0.13, 95% CI: 0.06-0.30) and 84% (RR = 0.16, 95% CI: 0.02, 1.64) for cohort and case-control studies, respectively. The effectiveness of COVID-19 vaccines were noted to offer higher protection against the DV among populations who received two vaccine doses compared with the unvaccinated population. This finding would help efforts to maximise vaccine coverage (i.e., at least 60% to 70% of the population), with two doses among vulnerable populations, in order to have herd immunity to break the chain of transmission and gain greater overall population protection more rapidly.
高传染性的新冠病毒德尔塔变异株（DV）导致病例激增，加剧了全球公共卫生危机。几种新冠疫苗在高度预防DV方面发挥了重要作用。本荟萃分析的主要目的是估计新冠疫苗在完全接种人群中相对于未接种人群，以风险比（RR）衡量对DV的合并有效性。我们进行了一项系统评价，并对2021年5月1日至2021年9月30日期间发表的、从临床角度聚焦于新冠疫苗对完全接种新冠疫苗人群（与安慰剂组即未接种人群相比）预防DV有效性的原始研究进行荟萃分析。共识别出11项包含1720万参与者数据的研究并纳入我们的研究。使用随机效应模型评估新冠疫苗对DV有效性（即风险比，RR）的合并估计值及95%置信区间。使用Egger回归检验和漏斗图评估发表偏倚，以调查潜在的异质性来源并识别研究设计中的任何差异。总共1720万（17,200,341人）人群被筛查新冠疫苗对DV的有效性。我们发现研究人群中有61.13%的人完全接种了两剂新冠疫苗。未接种人群中新冠病毒感染的加权合并发病率（20.07%）是完全接种人群（8.16%）的两倍多。总体而言，新冠疫苗对DV的有效性为85%（RR = 0.15，95% CI：0.07 - 0.31）。新冠疫苗的有效性因研究设计略有不同，队列研究和病例对照研究的有效性分别为87%（RR = 0.13，95% CI：0.06 - 0.30）和84%（RR = 0.16，95% CI：0.02，1.64）。与未接种人群相比，在接种两剂疫苗的人群中，新冠疫苗对DV显示出更高的保护效果。这一发现将有助于努力在脆弱人群中实现至少60%至70%的人群接种两剂疫苗以最大化疫苗接种覆盖率，从而获得群体免疫以打破传播链并更快地为更多总体人群提供保护。
