Ongoing trials are only designed to show whether vaccines prevent infection – and most infections are mild infections, said Peter Doshi, deputy editor of the BMJ medical journal and drug development specialist at the University of Maryland School of Pharmacy.
“I think there are some pretty widely held assumptions about what we’re getting from Phase 3 studies,” Doshi told CNN.
“None of the trials currently underway are designed to detect a reduction in any serious outcome such as hospitalizations, intensive care use or death. Vaccines are also not being studied to determine if they can interrupt transmission of the virus, ”Doshi said in the BMJ.
Four vaccines under development in the United States are at the most advanced stage of Phase 3 development: those manufactured by Moderna, Pfizer, AstraZeneca and Johnson & Johnson. These are ‘event-driven’ trials, which means the goal is to keep them going until a certain number of volunteers are infected. If more infections are seen in people who received a placebo or dummy injections, this is an indication that the vaccines prevented the infection.
But that doesn’t mean vaccines saved people from serious illness or death, Doshi argued.
“Serious illness requiring hospitalization, which occurs in only a small fraction of symptomatic Covid-19 cases, would likely not occur in significant numbers in trials,” he wrote.
The U.S. Food and Drug Administration’s Advisory Committee on Vaccines and Related Biologics meets on Thursday to discuss ongoing coronavirus vaccine trials and what members would like the FDA to consider when considering review of any request for emergency vaccine use or full approval.
Doshi said they should consider asking companies to reconfigure their trials to include data on the prevention of serious illness and death.
“People expect the worst part of the Covid iceberg – admissions, hospitalizations and deaths in intensive care – to be what a vaccine would end,” he said.
But current trials will only look for early infections. It is possible to continue these ongoing trials and complete them so that they eventually answer the question of whether Covid vaccines save lives and prevent serious illness.
“The trials are ongoing,” he told CNN. “There is a chance for that. It is not too late. “