As authorized COVID-19 vaccines are modified to protect against emerging strains of the pandemic disease, the UK will require only short clinical trials enrolling small numbers of volunteers to prove the altered vaccines are safe and effective, the UK’s Medicines and Healthcare products Regulatory Agency (MHRA) said.

“Only short-term results will be required, up to two months depending on the vaccine regimen …  seven-day reactogenicity data after each dose and unsolicited adverse events during this follow-up period should be collected,” the agency said, citing a guidance it developed with the ACCESS Consortium, a coalition of regulatory authorities from the UK, Australia, Canada, Singapore and Switzerland.

The MHRA’s approach is in line with those of the FDA (DID, Feb. 23) and the European Medicines Agency (DID, Feb. 26).

Enrollment numbers should be large enough to provide data about reactogenicity and immunogenicity, MHRA said. This could mean, for example, about 300 per cohort in a stand-alone study.

Some of the considerations in the guidance also apply to COVID-19 vaccines that have not yet been approved, and applicants should talk with the agency early, MHRA said.

Study sponsors for vaccines against emerging COVID-19 strains will benefit from the mass vaccination setting, the agency said, as “there is considerable safety experience accumulating as the pandemic progresses and vaccines are rolled out, and efficacy has been established for the initial vaccine candidate via large clinical phase 3 studies. This is a clear advantage as compared to the influenza mock-up concept where a pre-pandemic strain is used to estimate the safety and efficacy of a future candidate vaccine.”

Read the ACCESS Consortium guidance here: bit.ly/3c3B2Li. — Martin Berman-Gorvine