Data on adverse events no link to cause
More than 120 million people have received at least one dose of the COVID-19 vaccine as of Tuesday, but some anti-vaccine groups are using federal data to suggest those inoculations are unsafe.
The Centers for Disease Control and Prevention found “reassuring” results in a study of adverse effects during the first month the vaccine was distributed.
But claims circulating on social media point to the CDC’s national early warning system used to detect possible safety problems with vaccines as evidence of their danger. One Instagram post claimed a “6000% increase in reported vaccine deaths” in the first quarter of 2021 compared with the same period in 2020.
But the CDC’s Vaccine Adverse Event Reporting System and experts warn against using the data to draw conclusions about the safety of vaccines. Anyone can file a report in the system.
As of April 2, the system had received 1,934 reports of deaths in 2021, compared with 106 in all of 2020.
“There are limitations to VAERS data,” the CDC reports on its website. “A report to VAERS does not mean that the vaccine caused the adverse event, only that the adverse event occurred some time after vaccination.”
The Instagram account that shared the post about the increase did not respond to a request for comment. The far-right website The Gateway Pundit also posted about the data and did not immediately respond to a request for comment.
Limitations to VAERS data
The Vaccine Adverse Event Reporting System was established in 1990 in response to the National Childhood Vaccine Injury Act as a “vaccine safety surveillance program,” according to the CDC.
The CDC and the U.S. Food and Drug Administration run the “early warning system” used to detect safety problems with vaccines that scientists then can study to determine whether they represent actual risk.
Anyone can make a report in the system. It collects information about the type of vaccine received, when it was administered, when the adverse event started and current illnesses or medications. The form also asks whether the person has a history of adverse events after a vaccine and for demographic information.
Data in the system is publicly available but “often lack details and sometimes contain errors,” according to the CDC. The agency warns on its website that it isn’t possible to use the data to determine whether the vaccine caused the adverse event.
In fact, “vaccine providers are encouraged to report any clinically significant health problem following vaccination to VAERS, whether or not they believe the vaccine was the cause,” according to CDC’s website.
But the system is not designed to determine cause.
“Some adverse events might be caused by vaccination and others might be coincidental and not related to vaccination,” VAERS reports in an FAQ on its website. “Just because an adverse event happened after a person received a vaccine does not mean the vaccine caused the adverse event.”
The CDC did not respond to a request for comment.
“VAERS data has limitations,” said Lili Zhao, a research associate professor in biostatistics at the University of Michigan School of Public Health.
Zhao is studying the safety of COVID-19 vaccines using data from VAERS and other sources. If safety concerns pop up in the VAERS system, she said, it could warrant further analysis in other more reliable systems.
“Since it is a self-report system, submitting a report to VAERS does not mean that the vaccine caused or contributed to the death,” she said.
Put another way: Reports in the system are temporally associated with vaccines, but there is no causal link, said Amesh Adalja, senior scholar at the Center for Health Security in the Johns Hopkins Bloomberg School of Public Health.
How safe is the COVID-19 vaccine?
From Dec. 14, 2020, to March 29, the VAERS system received 2,509 reports of death among people who received a COVID-19 vaccine.
That represents 0.0017% of the 145 million doses administered in the U.S. during that period.
“A review of available clinical information including death certificates, autopsy, and medical records revealed no evidence that vaccination contributed to patient deaths,” according to CDC’s website.
Adalja pointed out that the U.S. prioritized the elderly, who are more likely to have other health problems that could contribute to death, during the earliest days of the vaccination drive.
The vaccines have proven to be effective in trials. Some versions showed more than 94% effectiveness in preventing symptomatic COVID-19.
Our rating: Missing context
Data in the Vaccine Adverse Event Reporting System can be submitted by anyone, and the CDC warns in several places that it cannot be used to determine the cause of an adverse event, including death. Experts agree with the CDC.