Official Warning: FDA Requires Pfizer and Moderna to Alert About Cardiac Risks in Their COVID-19 Vaccines
By: Alejandra Legarda | Special to Al Día News

In a decision that marks a new turn in the health oversight of COVID-19 vaccines, the U.S. Food and Drug Administration (FDA) has officially ordered pharmaceutical companies Pfizer and Moderna to update the labels of their mRNA vaccines to include explicit warnings about the risk of myocarditis and pericarditis. The move comes in response to an increase in reports of these adverse effects following the administration of the 2023–2024 formula.

According to a statement released by the FDA on May 20, 2025, the agency identified a “slightly higher incidence of heart inflammation” among adolescents and young adults—especially males between the ages of 16 and 30—compared to previous vaccination cycles. The companies have 30 days to submit an action plan and update their product labeling (FDA, 2025).

Pfizer and Moderna have issued preliminary responses, stating they are reviewing the agency’s request and affirming that their vaccines remain “safe and effective,” with benefits outweighing the risks, especially for individuals at high risk of severe COVID-19.

Although most reported cases have been mild and resolved quickly, the FDA emphasizes the importance of properly informing the public about these risks. A longitudinal study published in The Lancet in 2024 found that some patients with vaccine-related myocarditis showed persistent signs of heart inflammation up to five months post-vaccination (U.S. Food and Drug Administration).

Despite these warnings, health authorities stress that the benefits of vaccination outweigh the risks—particularly since COVID-19 infection itself can also cause myocarditis and other heart complications. A study published in JAMA in 2024 concluded that the risk of developing myocarditis is significantly higher after COVID-19 infection than after vaccination (Time).

Pfizer and Moderna now have 30 days to respond to the FDA’s request and submit the necessary labeling changes. This measure is part of an ongoing effort to ensure transparency and safety in vaccine administration.

In summary, while myocarditis and pericarditis are rare side effects associated with mRNA COVID-19 vaccines, the FDA considers it essential to provide clear information to the public—particularly to higher-risk groups—to maintain confidence in vaccination campaigns and support informed decision-making.