FDA guidance allows fast updates of COVID-19 vaccines

The FDA has issued guidelines allowing for faster development of updated coronavirus vaccines, based on previously approved shots that have been tweaked to combat emerging variants of the SARS-CoV-2 virus.

There is evidence that some of the emerging strains, particularly one that has emerged in South Africa, could be more resistant to vaccines developed to combat earlier versions of the virus.

Changes in the “Spike” protein targeted by nearly all the vaccines approved or in development could also lead to more infectious variants, such as the strain that emerged in Kent and is now prevalent across most of the UK.

As the virus is constantly evolving, there is need a to quickly develop and approve updated vaccines to neutralise new versions of the virus that may be able to evade the immune response from older vaccines.

The approach outlined by the FDA is based on previous experience with other vaccines against infectious diseases such as influenza, where shots are updated each year to combat emerging strains.

The FDA noted in updated guidance published at the beginning of the week that available information suggests that authorised vaccines provide protection against the currently circulating strains, but changes may be needed in the future.

If vaccines need updating, the FDA expects that manufacturing information will remain generally the same.

For clinical data, the FDA recommends using clinical immunogenicity studies that would compare the immune response to the modified vaccine with the response from the authorised vaccine.

Manufacturers are also encouraged to study the response in previously vaccinated and unvaccinated people.

These studies would be smaller and quicker to run than the phase 3 studies used for a first approval and the recommendations are in line with those expected from big pharma companies.

AstraZeneca’s executive vice president of BioPharmaceutiacls Mene Pangalos said that the company’s plans for updated vaccines rely on regulators accepting immunogenicity studies in a quarterly results briefing earlier this month.

Work on new versions to combat variants “started weeks and months ago,” Pangalos said.

“If regulators are okay with immunogenicity studies we aim to start vaccinating (with updated version) in the autumn,” he added.

Earlier this month the European Medicines Agency said it is also developing similar guidance and will publish a paper outlining the minimum regulatory requirements for vaccines that have been modified to counter new variants.

Topics covered will include the kind of bridging studies required to provide adequate reassurance of a vaccine’s efficacy against a new strain, either as a first vaccination or a booster.