• According to a new review, vaccines are an extremely safe way to protect human health
• This is thanks to strict, continuous safety monitoring
• However, many people still won’t get a coronavirus vaccine, even if it proves safe and effective  

Vaccines remain a “remarkably safe” way to protect human health, thanks to a rigorous system of safety monitoring that continues after approval, a new review shows.

Ongoing safety monitoring led to safety-related label changes in 25 out of 57 vaccines approved by the US Food and Drug Administration over a two-decade period, mostly related to the vaccine’s effect on specific groups of vulnerable people, an Israeli research team found.

“This report is the most comprehensive study of post-marketing vaccine safety published, and it shows that vaccines are remarkably safe, and that the current vaccine approval and post-marketing surveillance processes are robust and effective,” said senior researcher Dr Daniel Shepshelovich, of Tel Aviv University’s Sackler School of Medicine.

Adverse event reporting system

Vaccine hesitancy among Americans has been highlighted as a potential problem in the nation’s response to the Covid-19 pandemic, with some experts concerned that too many people simply won’t get a coronavirus vaccine even if one proves safe and effective.

“The current Covid-19 outbreak makes us further appreciate the importance of safe and effective vaccines against infectious diseases,” said Dr Daniel Mackey, a paediatrician with CHOC Children’s in Orange, California.

“As the world races to create a vaccine against Covid-19, we will now, more than any other time in recent history, be dependent on a robust vaccine adverse event reporting system to ensure that the chosen vaccines are safe for the greater population,” he said.

For the study, Shepshelovich and his colleagues tracked the progress of 57 vaccines that were FDA-approved between January 1996 and December 2015.

Researchers found that 25 of the vaccines had a total of 58 safety-related label changes that occurred following the approval.

Intestinal obstruction

More than a third of the label changes involved specific groups of people that were found to be potentially at a higher risk of health problems related to specific vaccines – for example, immune-compromised patients, pregnant women or preterm infants, Shepshelovich said.

Another 22% of label changes involved allergic reactions to vaccines, researchers reported. Most of these allergies related to latex used in the packaging.

Only one vaccine was withdrawn from the market, a rotavirus vaccine that increased the risk of an intestinal obstruction, researchers found.

“A timely alarm was sounded, and the vaccine was quickly removed from use,” Mackey said.

Robust studies

Overall, the safety monitoring data “represents an excellent track record, probably reflecting the professionalism and diligence of the personnel involved in the development, approval and regulation of vaccines,” Shepshelovich concluded.

Flu vaccines were found to have the fewest post-approval safety issues, with only three of 21 influenza vaccines requiring a label change, compared with 22 of 36 other vaccines.

“It’s important for people who have vaccine hesitancy to see that there are robust studies out there that support the use of vaccines,” said Dr Amesh Adalja, a senior scholar with the Johns Hopkins Center for Health Security in Baltimore.

“These are rigorously tested, and even after something is approved we’re continuing to track the safety of that vaccine,” he noted. “It really should give people who worry about vaccine safety a lot of confidence about how robust the process is for assessing the safety of these vaccines.”

The new study was published in the Annals of Internal Medicine.

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