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COVID-19 vaccine guidelines

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With multiple COVID-19 vaccines in and approaching phase III trials, the FDA has released development and licensure guidelines for these products.

The 21-page guidelines detail agency recommendations on everything from manufacturing and preclinical data considerations to trial design, efficacy considerations and post-licensure safety.

On trial efficacy, the agency lists laboratory-confirmed COVID-19 and laboratory-confirmed SARS-CoV-2 infection as acceptable primary end points. It recommends that the primary end point or a secondary end point be defined as virologically confirmed SARS-CoV-2 infection, with one or more of several listed symptoms of disease. It also notes that, because a COVID-19 vaccine might be more effective in preventing severe versus mild COVID-19, “severe COVID-19 should be evaluated as a secondary end point … if not evaluated as a primary end point”.

In terms of an efficacy thresholds, the agency calls for a primary efficacy end point point estimate of at least 50% protection.

The guidelines discuss possible surrogate end points, such as immune responses. But, it notes, “there are currently no accepted surrogate endpoints that are reasonably likely to predict clinical benefit of a COVID-19 vaccine”. Development programmes should instead focus on traditional approval via direct evidence of vaccine safety and efficacy in protecting humans from SARS-CoV-2 infection and/or clinical disease, it recommends.

The guidelines also stipulate that the pre-licensure safety database for preventive vaccines should consist of at least 3,000 study participants. Follow up of study participants should continue as long as feasible, “ideally at least one to two years”.

The ICMRA, a coalition of 30 regulatory bodies including the FDA and EMA, also recently published a summary of a workshop it held on regulatory requirements for COVID-19 vaccines. The ICMRA recommended that the primary end point should be laboratory-confirmed COVID-19 of any severity. The ICMRA has not as yet agreed on a specific numeric value for vaccine efficacy.

Nature Reviews Drug Discovery 19, 577 (2020)

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