Associated Data

With the use protocol will allow decisions to be made, informed of only RRRs, and omitting ARRs, reporting bias is by common criteria and uniform assessment. These introduced, which affects the interpretation of vaccine considerations on efficacy and effectiveness are based efficacy.

Assessing the suitability of vaccines must evidence that puts vaccine trial results in context and not consider all indicators, and involve safety, deployability, just looking at one summary measure, is also important. Such decisions should be properly informed by detailed We declare no competing interests. Published by Elsevier Ltd. Covid Vaccine Tracker. Click Engl J Med ; — Efficacy and safety of the mRNA methods for efficacy.

Lancet ; 99— It uses the relative risk RR —ie, the ratio of attack rates with and without a vaccine—which is expressed as 1—RR. However, RRR should be seen against the background risk of being infected and becoming ill with COVID, which varies between populations and over time. Although the RRR considers only participants who could benefit from the vaccine, the absolute risk reduction ARRwhich is the difference between attack rates with and without a vaccine, considers the whole population. Details are in the appendix p 3.

Supplementary Material

With the use of only RRRs, and omitting ARRs, reporting bias is introduced, which affects the interpretation of vaccine efficacy. Such decisions should be properly informed by detailed understanding of study results, requiring access to full datasets and independent scrutiny and analyses.

Unfortunately, comparing vaccines on the basis of currently available trial interim data is made even more difficult by disparate study protocols, including primary endpoints such as what is considered a COVID case, and when is this assessedtypes of placebo, study populations, background risks of COVID during the study, duration of exposure, and different definitions of populations for analyses both within and between studies, as well as definitions of endpoints and statistical methods for efficacy. Importantly, we are left with the unanswered question as to whether a vaccine with a given efficacy in the study population will have the same efficacy in another population with different levels of background risk of COVID This is not a trivial question because transmission intensity varies between countries, affected by factors such as public health interventions and virus variants. The only reported indication of vaccine effectiveness is the Israeli mass vaccination campaign using the Pfizer—BioNTech product.

Uncoordinated phase 3 trials do not satisfy public health requirements; platform trials designed to address public health relevant questions with a common protocol will allow decisions to be made, informed by common criteria and uniform assessment. These considerations on efficacy and effectiveness are based on studies measuring prevention of mild to moderate COVID infection; they were not designed to conclude on prevention of hospitalisation, severe disease, or death, or on prevention of infection and transmission potential. Assessing the suitability of vaccines must consider all indicators, and involve safety, deployability, availability, and costs. We declare no competing interests. Published by Elsevier Ltd.

Covid-19 vaccine efficacy and effectiveness—the elephant (not) in the room - the lancet microbe - variants

Published by Elsevier Ltd.

Elsevier hereby grants permission to make all its COVIDrelated research that is available on the COVID resource centre - including this research content - immediately available in PubMed Central and other publicly funded repositories, such as the WHO COVID database with rights for unrestricted research re-use and analyses in any form or by any means with acknowledgement of the original source.

References

This article has been cited by other articles in PMC. https://nda.or.ug/wp-content/review/entertainment/how-do-you-say-little-white-boy-in-spanish.php Data. In: Suchmacher M, Geller M, editors. This article has been cited by other articles in PMC.

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