A comprehensive review of 20 years of data reveals that US vaccines are remarkably safe, thanks in part to continued safety surveillance after vaccines hit the market, according to an Israeli study published Monday in the Annals of Internal. Medicine.
“Our study shows that even if a possible vaccine has a rare or long-term side effect that is not discovered in clinical trials, the surveillance program is underway to identify those problems as soon as possible,” said the study’s lead author, Dr. Daniel Shepshelovich, Vice President of Internal Medicine, Sourasky Medical Center, Tel Aviv.
“Most studies like this show a complicated picture, but here, we saw almost no complexity,” he said. “Vaccines are safe.”
Compared to similar studies that Shepshelovich has conducted on medical interventions, the new study shows that vaccines are much safer than many drugs, which can be beneficial but often carry side effects.
“Vaccines have almost no side effects and are especially safer than medical devices,” he said.
In the study, the researchers used data from the Vaccine Adverse Event Reporting System, or VAERS, a database created in 1990 by the Food and Drug Administration and the Centers for Disease Control and Prevention. The national surveillance system annually compiles around 30,000 reports related to potential vaccine safety concerns from healthcare professionals, vaccine manufacturers, and the public. The FDA continually monitors reports to find patterns or peaks in reported adverse events for a particular vaccine.
The researchers examined the post-approval safety concerns that VAERS collected in the 57 vaccines that the FDA approved from January 1996 to December 2015. Most of the newly approved vaccines were annual flu vaccines. The team found 58 post-marketing safety-related label changes associated with 25 vaccines and determined that the changes are of limited importance.
Nearly 40 percent of the updated safety guidelines were related to restricting the use of the vaccine in certain groups, such as immunocompromised people, pregnant women, and premature babies, who were remedied by not giving them the vaccine. The second most common update, accounting for more than 20 percent of post-market modifications, was related to allergies, almost always with latex packaging.
About 20 percent of the safety modifications were related to patients fainting after receiving the vaccine, although Shepshelovich said it may be due to people who were afraid of the needles, rather than a side effect of the vaccine itself. . Five percent of the updates actually removed the previous warnings and precautions, and only one rotavirus vaccine was withdrawn in 1999.
This study shows once again that vaccines are one of the safest interventions we have.
“This study shows once again that vaccines are one of the safest interventions we have,” said Tara Smith, professor of epidemiology at Kent State University in Ohio. “The problems they saw were largely fixable by simply changing who the vaccines are given.”
Smith, who was not involved in the new research, said the reason some safety concerns go undetected during clinical trials is that Phase 3 clinical trials include thousands of people, rather than the millions receiving a vaccine. once it is part of standard practice.
“Even the largest clinical trial we have will be even smaller than the number of people who receive the vaccine once it is used in the population,” he said. “Post-approval surveillance may show minor problems in certain populations that were lost in initial clinical trials but are still detected over time.”
In fact, that’s why strong safety surveillance programs are needed, said Dr. Paul Offit, director of the Vaccine Education Center at the Children’s Hospital of Philadelphia, who was also not involved in the new study.
“The important thing is that you have systems to detect these adverse reactions, and in the US, we have multiple layers of systems that do this,” he said. Surveillance programs will be particularly important for the COVID-19 vaccine, he added, because most vaccines take at least 15 years to develop and be tested in clinical trials, while development of a coronavirus vaccine can take as little as 18 months.
Still, Shepshelovich said he believes the FDA will take additional precautions in monitoring the possible adverse effects of a COVID-19 vaccine because the world is paying close attention.
Offit agreed. “I think the FDA and CDC will be extremely vigilant about monitoring the possible side effects of the SARS-CoV-2 vaccine, as they are for every vaccine given to children,” he said. (SARS-CoV-2 is the name of the coronavirus that causes COVID-19).
However, an anti-vaccine movement has found support among some people. Another article published Monday in the journal Pediatrics reported that vaccination rates against measles, mumps, and rubella in 20 states have dropped below 90 percent. A 95 percent immunization rate is needed to stop the spread of measles.
“I think you should be skeptical of anything you put into your body. You want to see the data and you want to make sure these vaccines are of a high standard,” Offit said. “What it shouldn’t be is cynical when there is data showing that the benefits of vaccines outweigh the potential risks. The notion that the FDA or CDC is hiding something is not even close to the truth.”
Shepshelovich said he understands that some people will not accept his study’s findings.
“But if you look at the facts, they are very, very clear,” he said. “Vaccines are safe.”
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