Any COVID-19 vaccine the FDA approves would have to be at least 50 percent more effective than a placebo, according to a new guidance it released yesterday.
In comparison, the flu vaccine has ranged in effectiveness from 10 percent to 60 percent from 2004 to 2018, according to CDC statistics.
A COVID-19 vaccine would also need to prevent disease or lessen disease severity in at least half of vaccinated patients, the guidance said, adding that the pre-approval safety database should include at least 3,000 study participants vaccinated with the dosing regimen intended for approval.
In addition, the guidance said, FDA expects vaccine developers to conduct postmarket safety monitoring of study participants. Follow-up should be conducted in particular for severe COVID-19 disease manifestations for “as long as feasible” — at least one to two years — in order to gauge the vaccine’s duration of protection and the potential for vaccine-associated enhanced respiratory disease (ERD) as immune responses wane.
Because of the potential for vaccine-associated ERD, developers should conduct studies to assess their vaccine candidates for ERD risk. The guidance notes that vaccine studies in animal models for other coronaviruses have shown evidence of immunopathologic lung reactions in infants and animals, so a COVID-19 vaccine could potentially induce vaccine-associated ERD in humans.
Developers should evaluate the vaccine in COVID-19-infected humans and should enroll diverse populations in trials, including minorities, elderly patients and patients with medical comorbidities, as well as pregnant women and pediatric patients, the guidance said.
As more is learned about SARS-CoV-2 immunology and vaccine immune responses, vaccine developers may want to consider using the agency’s accelerated approval pathway, the FDA said.
“We firmly believe that transparency regarding the FDA’s current thinking about the scientific data needed to support approval of safe and effective COVID-19 vaccines will help build public confidence in the FDA’s evaluation process, which will be critical in ensuring their use,” said Peter Marks, director of the FDA’s Center for Biologics Evaluation and Research.
Nonclinical safety studies may not be needed prior to first-in-human trials if there is enough information to characterize safety from other sources, according to the guidance.
“Vaccine manufacturers should summarize the findings and provide a rationale if considering using these data in lieu of performing nonclinical safety studies,” the agency said.
Read the full guidance here: www.fdanews.com/06-30-20-Guidance.pdf. — James Miessler