Healthy Returns: FDA may add its strongest safety warning to Covid vaccines. Here’s what to know

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The Food and Drug Administration may add its strongest safety warning to Covid shots – marking another major shift in vaccine oversight. 

It could also expand a string of actions by Trump administration health officials that some health experts say could weaken confidence in the shots, which have saved millions of lives worldwide since they were introduced. Uptake of those vaccines is already plummeting: The National Foundation for Infectious Diseases, citing IQVIA data, said last week that there has been a 27% decrease in Covid vaccinations from retail pharmacies since 2024.  

Here's what we know so far.  

The FDA is preparing to add what's known as a "black box" warning to Covid vaccines by the end of the year, CNN first reported on Friday. 

That plan, which is not finalized, is being driven by Dr. Vinay Prasad, the FDA's chief medical and scientific officer and director of the agency's Center for Biologics Evaluation and Research, CNN reported. 

That type of label isn't used lightly. It appears at the top of a medicine's prescribing information and is designed to warn about risks such as death or serious injuries that should be weighed against a product's benefits. 

For example, boxed warnings on opioids warn about risks of addiction, overdose and death. 

But there are still a lot of unanswered questions here. 

First of all, the Health and Human Services Department did not confirm any of the plans today. 

In a statement to CNBC, HHS spokesperson Andrew Nixon said, "Unless the FDA announces it, any claim about what it will do is pure speculation."

We also don't know if this warning will apply to all three Covid vaccines. 

HHS Secretary Robert F. Kennedy Jr. – a prominent vaccine skeptic – and some of his appointees have previously targeted mRNA Covid shots from Pfizer and Moderna. 

But Novavax also offers a protein-based Covid vaccine. 

It's also unclear if this warning will only apply to certain age groups and what issue the label will point to. 

Prasad, in an internal FDA memo last month, tried to link 10 deaths in children to Covid vaccines, without providing any evidence. He also highlighted myocarditis, an extremely rare side effect after administration of mRNA shots from Pfizer and Moderna. Cases of that side effect were detected with early use of the jabs, when first and second doses were recommended to be taken as closely as three weeks apart. The side effect was also predominantly seen in boys and men. 

But health authorities worldwide, including the Centers for Disease Control and Prevention, have emphasized that the benefits of vaccination in preventing severe Covid and even myocarditis from the infection itself far outweigh the small risk of the side effects posed by the shot. Cases of myocarditis have also declined dramatically in recent years. 

So what are the vaccine makers saying in response today? 

Pfizer pointed to previous statements supporting the safety and efficacy of its Covid vaccine. 

The shot has "consistently provided strong protection against symptomatic and severe COVID-19 disease across multiple variants and subvariants, resulting in over 14 million lives saved globally in the first year after approval – and many more since then," Pfizer said.

Moderna pointed to a statement it issued in September, which says the safety of its Covid vaccine is "rigorously monitored" by the company, the FDA and regulators across more than 90 countries. With more than a billion doses distributed worldwide, those systems "have not reported any new or undisclosed safety concerns in children or pregnant women," the statement said.

We'll be watching closely to see if the FDA adds these warnings to the shots, so stay tuned for our coverage.

Feel free to send any tips, suggestions, story ideas and data to Annika at a new email: annika.constantino@versantmedia.com.