FDA Mandates Label Warnings for Pfizer/BioNTech and Moderna COVID-19 Vaccines Over Rare Heart Inflammation Risk

Compiled by | Fan Dongdong

Currently, many novel coronavirus vaccines face development delays and safety and supply issues, but the mRNA vaccines from Pfizer/BioNTech and Moderna have emerged as frontrunners in their class, relatively unimpeded by these constraints.

However, on June 24, foreign media reported that U.S. experts concluded there is a "possible link" between rare cases of heart inflammation and mRNA vaccines, which has had a certain negative impact on Pfizer/BioNTech and Moderna vaccine shots.

The FDA stated it will take swift action to require these companies to add labeling warnings indicating that young people and adolescents are susceptible to side effects.

Although the U.S. Centers for Disease Control and Prevention (CDC) concluded that the benefits of the vaccine clearly outweigh the risks, this decision may drive those with safety concerns to favor the adenovirus vaccines provided by Johnson & Johnson and AstraZeneca. Earlier this year, these vaccines also faced safety issues due to reports of rare but severe blood clots. Following an investigation, Johnson & Johnson's vaccine now carries a warning in the United States.

The latest ruling pertains to young individuals (predominantly male) who primarily developed myocarditis (inflammation of the heart muscle) or pericarditis (inflammation of the heart lining) after receiving the second dose of an mRNA vaccine. The U.S. Centers for Disease Control and Prevention reported that 309 individuals have been hospitalized; to date, all but 14 have been discharged, and there have been no reported deaths.

Data from the CDC's Vaccine Safety Datalink indicates that among individuals aged 12 to 39, the incidence rate of cardiac inflammation is 12.6%, with over 138 million Americans having been fully vaccinated with the Pfizer/BioNTech or Moderna vaccines. Cases of cardiac inflammation are more frequent among recipients of the Pfizer/BioNTech vaccine; however, this is largely attributable to the FDA's approval of the Pfizer/BioNTech vaccine for individuals aged 12 and older, whereas the Moderna vaccine has not yet been authorized for use in individuals under 18.

Pfizer Inc. said in a statement: "Heart inflammation is an extremely rare side effect that occurs in only a very small number of individuals following vaccination, and patients typically recover quickly with conservative treatment. It is important to note that the CDC continues to strongly encourage eligible individuals aged 12 and older to receive the COVID-19 vaccine. Hundreds of millions of doses of the Pfizer-BioNTech COVID-19 vaccine have been administered worldwide, and the benefit-risk profile of our vaccine remains positive."

Moderna issued a similar statement, adding that the company will work closely with the FDA and other regulatory agencies to take appropriate next steps.

Reference: Pfizer, Moderna COVID-19 vaccines will get label warning over rare heart risk, FDA says