Health Experts Criticize FDA Covid-19 Vaccine Plan
Several health experts are attacking FDA’s recent guidance on minimum requirements for Covid-19 vaccines to obtain an emergency use authorization (EUA). In comments offered during a 10/22 FDA Vaccines and Related Biological Products Advisory Committee meeting, National Center for Health Research president Diana Zuckerman said the vaccine trials have serious design flaws. “The standards set in FDA guidances and the study protocols make it likely that vaccines that will be authorized or approved won’t achieve what the public and policy makers expect,” she told the advisory committee. “Instead, these vaccines will only be proven to reduce the risk of mild infections but not proven to reduce the risk of hospitalization, ICU use, or deaths.”
Zuckerman said she was bothered by FDA’s requirement of at least two months median follow-up after vaccination or placebo, which she said was too short to study efficacy. “Even if a person is exposed during that time, we don’t know the correlates of protection and so we need a longer follow-up to know how long an effective vaccine remains effective,” she said. “We can’t rely on post-market studies for that information, because once a vaccine is on the market, many people in the placebo control group will switch to a vaccine.”
Public Citizen’s Health Research Group founder Sidney Wolfe said he was worried that public confidence in a Covid-19 vaccine has diminished. He said “rushing a vaccine through an EUA without complete Phase 3 safety and efficacy data, which could take months to complete, would further undermine public confidence... The gap between completed Phase 3 trials needed for approval and the current EUA standard, allowing half of Phase 3 trial participants to be followed for less than two months after vaccination does not engender confidence. Saving time by a faster but riskier data-deficient EUA pathway will surely be outweighed by further loss in public confidence in an incompletely tested, vaccine, accompanied by decreased willingness to be vaccinated.”
Emergency Care Research Institute (ECRI) CEO Marcus Schabacker said in his comments that after “reviewing the limitations of Covid-19 vaccine testing and the potential harms that vaccines might cause, ECRI recommends that U.S. authorities approve Covid-19 vaccines only after a full review of completed clinical trials that also considers evidence limitations and gaps, and under no circumstances authorize Covid-19 vaccines before six-month follow-up data from the full trial cohort are reviewed.” He said ECRI believes that the greatest risk would be deploying a safe but weak Covid-19 vaccine, which might actually worsen the pandemic. “In principle, even a partially effective vaccine should help slow down transmission as long as people maintain social distancing, hygiene practices, and personal protective equipment (PPE) use,” he told the committee. “However, public response and attitudes over the past nine months in the U.S. suggest that hygiene precautions might relax as soon as a vaccine is available. Resulting infections may offset the vaccine’s impact and end up increasing the mortality and morbidity burden.”
Schabacker said that relying on preliminary data to support an EUA should be considered at “high risk of bias regardless of trial design because what can happen at subsequent time points in the study is unpredictable.” The vaccine trials are even more susceptible because key variables, such as infection risk and immunity, are time-dependent, he said. “Moreover, patient demographics at an interim analysis might differ from those in the full study cohort — and from the general population — in unexpected ways; for example, early trial volunteers could be from geographic areas practicing better social distancing than in other areas,” he contended.