(NEWSMAX) – Thousands of volunteers participating in studies of the Pfizer-BioNTech and Moderna COVID-19 vaccines continue to be involved in follow-up research, but many in the placebo group have now gotten their vaccinations, meaning it may be difficult for the companies to answer questions about the medications.
"We don't know how long protections last," Dr. Steven Goodman, a clinical trials specialist at Stanford University, told NPR, explaining that losing control groups will make it more difficult to answer important questions about the vaccines. "We don't know efficacy against variants — for which we definitely need a good control arm — and we also don't know if there are any differences in any of these parameters by age or race or infirmity."
Volunteers signing up for studies last year did not get promises of special treatment when it comes to getting vaccines, but the companies opted to offer the shots once the Food and Drug Administration authorized them.
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