COVID Vaccine Trial Setback: Pfizer, BioNTech Halt Study Over Low Enrollment
Pfizer
London: Vaccine makers Pfizer and BioNTech have halted recruitment for a large U.S. trial of their updated COVID-19 vaccine in healthy adults aged 50 to 64, saying enrollment in the trials had been too low to generate the needed data.
In a letter to trial investigators dated March 30, seen by Reuters and previously unreported, Pfizer said that it would stop surveillance for signs of COVID illness of all participants in the study after April 3.
Enrollment was closed on March 6, following a review of current epidemiological trends, it said.
The move comes as COVID vaccine makers grapple with pushback from the U.S. administration and weak U.S. uptake. The U.S. Food and Drug Administration toughened requirements for COVID vaccine use last year, including asking for large, placebo-controlled trials in the 50-64 age group for it to be included in recommendations.
No COVID vaccines have since been approved for that group.
Pfizer and BioNTech told Reuters they had informed the FDA about their intent to halt the COVID-19 vaccine study, citing challenges getting enough participants. The target enrollment was roughly 25,000 to 30,000 participants.
"This study is not ending as a result of any safety or benefit-risk concerns. We intend to stop the study due to slow enrollment and therefore the inability to generate relevant post-marketing data," the companies said.
The FDA was not immediately available for comment.
