— Agency to ask advisors to weigh in on plan similar to the annual influenza vaccine
Programmatic implications for regular COVID boosters will be foremost on the agenda at an FDA advisory committee meeting on Wednesday, according to briefing documents released by agency staff.
At the April 6 meeting, FDA is asking its Vaccines and Related Biological Products Advisory Committee (VRBPAC) to not only lay out parameters for how to determine when it might be necessary to update the composition of COVID boosters, but how often and how it might be applied to both approved and authorized vaccines.
In the documents released on Monday, FDA staff appear to be nudging VRBPAC toward a structure similar to that of influenza vaccines, “an approach where strain modifications could be supported by manufacturing information alone,” which would be supported by clinical immunogenicity and safety data, as opposed to the current policy that requires clinical data.
At its core, agency staff argued for the need to expand the scope of COVID vaccines to a more global scale with “coordinated strain selection,” similar to influenza. They also noted that while the World Health Organization and FDA coordinate on selecting strains for the seasonal influenza vaccine every year, there are a number of key differences between influenza and SARS-CoV-2 to take into account.
The most important difference is that unlike influenza, COVID does not have “predictable winter seasonality,” where manufacturers can implement recommendations based on flu patterns in the Northern or Southern hemispheres. By contrast, “a predictable pattern for SARS-CoV-2 has yet to emerge,” FDA staff noted.
“At this time, it is not clear if or when the epidemiology of SARS-CoV-2 will fall into a pattern that will make a global recommendation for an updated COVID-19 vaccine composition obvious or needed,” they wrote.
Agency staff recommended three criteria for potentially changing the COVID vaccine strain composition:
- Sufficient data exist to “suggest the need for a better matched vaccine”
- Evidence that a new vaccine “will provide a significantly better outcome than current vaccines”
- Manufacturers have the ability and capacity to produce these new vaccines
Manufacturing was listed as another sticking point for changing COVID booster strains. Influenza vaccines are on similar platforms, making it easier to update, with agency staff writing, “it is not clear whether the various platforms used for authorized and approved COVID-19 vaccines can accommodate an updated composition in similar timeframes.”
Finally, FDA staff addressed timing of future booster doses, as well as populations, noting that additional boosters should “optimally prevent hospitalization and death in those at greatest risk,” with the idea that these future variants could emerge essentially during the 2022-2023 flu season or “at least a significant portion” of it.
They also emphasized the importance of preventing symptomatic disease, in the hopes of preventing long COVID. And while they addressed the potential associated risks of additional boosters, such as vaccine-associated myocarditis, they also hypothesized that “the potential benefits of the generation of a broader immune response that may address emerging variants across the entire population may be determined to outweigh known and potential risks.”
FDA staff also asked VRBPAC to discuss topics related to COVID epidemiology, vaccine effectiveness, as well as “practical aspects and goals of public health vaccination programs.”