Pfizer and BioNTech Pause Covid Vaccine Study Following Low Enrollment Totals

By Nicholas Jacobus

April 3, 2026

Source: Pharm Exec

Photo / Image Source: Unsplash,

Key Takeaways

• Pfizer and BioNTech stopped COVID-19 illness surveillance after April 3 following enrollment closure, citing inadequate recruitment to meet FDA-required post-marketing evidence thresholds.

• Restrictive eligibility excluding prevalent comorbidities (e.g., hypertension, diabetes) caused >80% pre-screen failures, making accrual of 25,000–30,000 healthy adults aged 50–64 infeasible.

• No full FDA approval exists for healthy 50–64-year-olds; without large placebo-controlled data, expanding recommendations/authorization for this cohort is now uncertain.

• Reduced booster uptake and heightened FDA evidentiary requirements in lower-risk groups are converging with political headwinds, complicating COVID vaccine lifecycle strategies.

• Moderna’s parallel 30,000-participant U.S. trial remains active but is also experiencing recruitment friction, with projected completion in 2027.

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