Effectiveness and safety of SARS-CoV-2 vaccine in real-world studies: a systematic review and meta-analysis

Abstract

Background To date, coronavirus disease 2019 (COVID-19) becomes increasingly fierce due to the emergence of variants. Rapid herd immunity through vaccination is needed to block the mutation and prevent the emergence of variants that can completely escape the immune surveillance. We aimed to systematically evaluate the effectiveness and safety of COVID-19 vaccines in the real world and to establish a reliable evidence-based basis for the actual protective effect of the COVID-19 vaccines, especially in the ensuing waves of infections dominated by variants. Methods We searched PubMed, Embase and Web of Science from inception to July 22, 2021. Observational studies that examined the effectiveness and safety of SARS-CoV-2 vaccines among people vaccinated were included. Random-effects or fixed-effects models were used to estimate the pooled vaccine effectiveness (VE) and incidence rate of adverse events after vaccination, and their 95% confidence intervals (CI). Results A total of 58 studies (32 studies for vaccine effectiveness and 26 studies for vaccine safety) were included. A single dose of vaccines was 41% (95% CI: 28–54%) effective at preventing SARS-CoV-2 infections, 52% (31–73%) for symptomatic COVID-19, 66% (50–81%) for hospitalization, 45% (42–49%) for Intensive Care Unit (ICU) admissions, and 53% (15–91%) for COVID-19-related death; and two doses were 85% (81–89%) effective at preventing SARS-CoV-2 infections, 97% (97–98%) for symptomatic COVID-19, 93% (89–96%) for hospitalization, 96% (93–98%) for ICU admissions, and 95% (92–98%) effective for COVID-19-related death, respectively. The pooled VE was 85% (80–91%) for the prevention of Alpha variant of SARS-CoV-2 infections, 75% (71–79%) for the Beta variant, 54% (35–74%) for the Gamma variant, and 74% (62–85%) for the Delta variant. The overall pooled incidence rate was 1.5% (1.4–1.6%) for adverse events, 0.4 (0.2–0.5) per 10 000 for severe adverse events, and 0.1 (0.1–0.2) per 10 000 for death after vaccination. Conclusions SARS-CoV-2 vaccines have reassuring safety and could effectively reduce the death, severe cases, symptomatic cases, and infections resulting from SARS-CoV-2 across the world. In the context of global pandemic and the continuous emergence of SARS-CoV-2 variants, accelerating vaccination and improving vaccination coverage is still the most important and urgent matter, and it is also the final means to end the pandemic. Graphical Abstract

Emergence of SARS-CoV-2 Omicron (B.1.1.529) variant, salient features, high global health concerns and strategies to counter it amid ongoing COVID-19 pandemic

“…The challenge in the drive of vaccination is the less likelihood of vaccination in ethnic minority groups and less vaccination in financially deprived groups ( Rae, 2021 ). As vaccination has been proven quite effective in the management of COVID-19 and to prevent high burden of disease severity ( Nainu et al, 2020 ; Liu et al, 2021 ), people residing in low-income and less-developed countries should be a top priority subject for mass vaccination ( He et al, 2021 ). During the time of pandemic when many variants are appearing one after one with variable disease severity and transmissibility, clarity of messages is essential which have been changed time to time from “stay home” to “stay alert,” and many people may find it quite puzzling and it could be explained as “Alert Fatigue” ( McKee, 2021 ).…”

Development of an in-house Quantitative ELISA for the Evaluation of Different Covid-19 Vaccines in Human

“…However, di culties facing vaccinologists include predicting the type and timing of the next pandemic; developing vaccines to combat rapidly changing pathogens; and establishing rapid-response strategies to control emerging and reemerging infectious diseases. Against COVID-19, developed vaccines have shown acceptable safety records and could effectively reduce the death, severe cases, symptomatic cases, and infections resulting from SARS-CoV-2 across the world [24]. In the context of global pandemic and the continuous emergence of SARS-CoV-2 variants, accelerating vaccination and improving vaccination coverage is still the most important target.…”

“…For the other surveyed vaccine platforms, the enrolled COVID-19 naïf recipients are rather low and robust interpretations cannot be driven. In a systematic review and meta-analysis of 58 studies, the pooled vaccine effectiveness was 85% (80-91%) for the prevention of Alpha variant of SARS-CoV-2 infections, 75% (71-79%) for the Beta variant, 54% (35-74%) for the Gamma variant, and 74% (62-85%) for the Delta variant [24]. It seems undoubtable that all the current COVID-19 vaccines have a drop of effectiveness against the emerging variants.…”

Long-lasting cellular immunity to SARS-CoV-2 following infection or vaccination and implications for booster strategies

“…Anti-COVID-19 vaccines have shown remarkable efficacy both in phase 3 clinical trials as well as in real world studies, demonstrating protection against severe disease and infection [12][13][14]. Vaccination leads to the development of humoral and cellular immunity against spike [3,10].…”