The trials are scheduled to conclude in 2026 or 2027.
Companies that manufacture COVID-19 vaccines have pledged to conduct fresh trials for the shots, according to newly released documents.
Pfizer and BioNTech have committed to carrying out a randomized, double-blind, placebo-controlled trial to evaluate the safety and efficacy of their COVID-19 vaccine in adults aged 50 to 64 who do not have any conditions that are said to place them at increased risk for severe COVID-19, Dr. David Kaslow, an official with the Food and Drug Administration, said in one of the documents, an approval letter to the companies, dated Aug. 27.
Moderna has conveyed a written commitment to conduct a randomized, observer-blind, placebo-controlled study testing the safety of its two COVID-19 vaccines in the same population, Kaslow said in another letter, sent to the company.
Novavax has pledged to run a randomized, observer-blind, placebo-controlled trial in the same population “to evaluate the circulating vaccine-derived spike protein,” based on “a comprehensive symptom survey,” according to Kaslow’s letter to Novavax.
The Pfizer study is slated to be completed on July 31, 2026, according to the documents. The company will have until Jan. 31, 2027, to complete its final report on the trial.
Moderna’s trial is to end by Jan. 31, 2027, with a final report due one year later. Novavax’s trial is not slated to be finished until Nov. 30, 2027. Its final report is not due until May 31, 2028.
The companies did not respond to requests for comment.
The FDA referred a request for comment to its parent agency, the Department of Health and Human Services, which pointed to memorandums from Dr. Vinay Prasad, the FDA’s top vaccine official, on the new approvals.
Prasad said in the memos that encouraging the companies to run randomized clinical trials would help regulators determine if the benefits of the vaccines outweigh the risks in younger, healthy individuals.
“FDA has a statutory mandate to only approve products when we have substantial certainty benefits outweigh harms and, in cases when we do not, sponsors are free to prove to the agency and the American people the worth of their products with randomized trials,” he said in one memo.
