key: cord-0748693-8fcaflzp
authors: Deng, Jiawen; Heybati, Kiyan; Zhou, Fangwen
title: Response to “Safety and effectiveness of SARS‐CoV‐2 vaccines: A systematic review and meta‐analysis”
date: 2021-08-17
journal: J Med Virol
DOI: 10.1002/jmv.27269
sha: 4bd4baa4a5864fbe928bf1389e6543d8cabed667
doc_id: 748693
cord_uid: 8fcaflzp

nan

Response to "Safety and effectiveness of SARS-CoV-2 vaccines: A systematic review and meta-analysis"

To the Editor,

We read with great interest the systematic review and meta-analysis on the safety and efficacy of SARS-CoV-2 vaccines by Ling et al. 1 The authors included nine randomized controlled trials (RCTs) in their analyses and concluded that the incidence of adverse events associated with SARS-CoV-2 vaccines is greater versus placebo. We are grateful for the authors' up-to-date analysis on the efficacy and safety of SARS-CoV-2 vaccines, which has garnered considerable attention during the pandemic.

However, there are major limitations in the authors' methodology and interpretation that need to be addressed to ensure correct application of the findings.

First, the authors used several outdated frameworks and did not report essential information regarding their review. Specifically, neither a detailed search strategy including any pertinent RCT filters, nor any identification number for the prospective registration of their review such as a PROSPERO number, 2 was reported. Additionally, the authors only identified 91 items after their systematic searches. A review on the same topic by Pormohammad et al. 3 identified 32 790 initial items, and therefore, it is difficult to assess whether all of the available evidence was included. Furthermore, they did not conduct the review with the most up-to-date methodology, such as PRISMA 2020 guidelines, 4 RoB 2, 5 and the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) framework. 6 Lastly, the authors did not indicate that any screening or extraction process was conducted in duplicate. These components are essential to the integrity and reproducibility of systematic reviews, and are requirements in both PRISMA and Cochrane guidelines.

Second, the author used I 2 statistics to determine the use of a fixed versus random-effects model for their meta-analysis. This approach does not align with the Cochrane handbook which specifically states that "the choice between a fixed-effect and a random-effects meta-analysis should never be made on the basis of a statistical test for heterogeneity." 7 Rather, this decision should have been made on the basis of the level of similarity between study characteristics. 8 Considering that the authors' analyses involved different types of vaccines across different platforms, with varied participant demographics, a random-effects model should have been implemented, even for analyses with low statistical heterogeneity.

Moreover, the authors did not appropriately assess the sig- for instance, the OR of inactivated virus vaccine adverse events is

Safety and effectiveness of SARS-CoV-2 vaccines: a systematic review and meta-analysis

PROSPERO: an international register of systematic review protocols

Efficacy and safety of COVID-19 vaccines: a systematic review and meta-analysis of randomized clinical trials. Vaccines (Basel)

The PRISMA 2020 statement: an updated guideline for reporting systematic reviews

RoB 2: a revised tool for assessing risk of bias in randomised trials

GRADE Working Group. Letters, numbers, symbols and words: how to communicate grades of evidence and recommendations

Cochrane Handbook for Systematic Reviews of Interventions

Demystifying fixed and random effects meta-analysis

Phase I/II study of COVID-19 RNA vaccine BNT162b1 in adults

Vaccine side-effects and SARS-CoV-2 infection after vaccination in users of the COVID Symptom Study app in the UK: a prospective observational study

Understanding vaccine hesitancy in COVID-19