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Effectiveness of heterologous and homologous covid-19 vaccine regimens: living systematic review with network meta-analysis

BMJ 2022; 377 doi: https://doi.org/10.1136/bmj-2022-069989 (Published 31 May 2022) Cite this as: BMJ 2022;377:e069989

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Re: Effectiveness of heterologous and homologous covid-19 vaccine regimens: living systematic review with network meta-analysis

Dear Editor

I was surprised that there was not a single forest plot or table of the estimates extracted from each of the included studies, even in the supplementary materials. This should have been picked up by peer reviewers and would be important to allow reproducibility checks. I was also surprised that authors pooled VE across variants and across age groups when these are well established heterogeneities in VE by age and by variant that would indicate against pooling. There may even be interactions between vaccine type and variant if some vaccine technologies are better than others at providing broad immunity. I'm glad it's a living review and I look forward to seeing updates in the coming months to include a table of the raw extracted values from each study as well as more and more publications reporting VE estimates against Omicron. The comprehensive reference list will be very useful.

Regards
Ben

Competing interests: No competing interests

01 June 2022
Benjamin J Cowling
Professor
The University of Hong Kong
7 Sassoon Road, Pokfulam, Hong Kong