EXPLAINER: How activists target CDC vaccine tracking system

Once, getting vaccinated was all but routine. But since the heightened public awareness around the new COVID-19 vaccines, it’s a different story. Now, it means check-ins with family and friends about possible arm soreness or mild symptoms.

Through an early warning system known as the Vaccine Adverse Event Reporting System, the U.S. Centers for Disease Control and Prevention and the Food and Drug Administration keep tabs on signals of possible side effects from vaccines. The federal agencies have maintained the system since 1990 as part of a transparent way to ensure vaccine safety.

Federal officials are not the only ones keeping an eye on the reports. Over the years, anti-vaccine proponents have seized on the publicly available data to sow doubt about vaccines from falsehoods that they cause autism to even death.

But the reporting tool does not offer official proof that the vaccines caused any of the events listed despite what anti-vaccine advocates may say.

Here’s a look at how the system works and how it has been misused:


VAERS uses passive surveillance, meaning people self-report by submitting their personal information, when they received the vaccine, the brand of the vaccine and the date they began experiencing any negative reactions. Anyone can submit a report on any possible reaction after the vaccine and anyone can access it.

Health care providers and manufacturers are required to submit adverse responses reported after vaccines, even if they don’t know whether the vaccine caused them.

The surveillance mechanism does not monitor people who have not received the vaccine or people who were vaccinated and reported no side effects.

“For example, if you get a vaccine and then you get struck by lightning, you can report that to VAERS,” said Dr. Sean O’Leary, vice chair of the committee on infectious diseases for the American Academy of Pediatrics and professor of pediatrics at the University of Colorado.

A VAERS submission does not mean that the vaccine is responsible for any of the events reported. That requires further investigation by medical officials to determine if there is any link. When serious events are reported in VAERS, CDC and FDA scientists follow up with the person reporting the event to obtain more information and medical records.


Although anyone can report to VAERS, the system does offer important safety signals to health care professionals and federal officials.

VAERS identifies unusual patterns that can help alert medical professionals to investigate further. For instance, in the case of the COVID-19 vaccines, health care officials were able to note early reports of anaphylaxis with the Pfizer-BioNTech vaccine and rare blood clots forming after the Johnson & Johnson vaccine.

Dr. Tom Shimabukuro, who heads the CDC’s COVID-19 vaccine safety monitoring efforts, said three deaths have been confirmed after the serious blood clots.


With an increasing number of the American public becoming vaccinated, anti-vaccine supporters have taken to uploading screenshots of VAERS data showing poor reactions and posting them with misleading captions on social media.

When the COVID-19 vaccines were prioritized for elderly residents of long-term care facilities, they capitalized on reports of deaths in nursing homes.

Considering that many early vaccinations went to people in their 80s and 90s with chronic health problems, coincidental deaths afterward weren’t surprising, Shimabukuro said.

Soon after, online posts targeted pregnant women — who had been left out of clinical trials — to falsely claim that large numbers of women were experiencing miscarriages from the vaccine, but the reality was that vaccines were deemed safe during pregnancy.

The latest attempt to undermine vaccine efforts uses VAERS figures to suggest that COVID-19 vaccines have caused more than 3,000 deaths since December. Fox News host Tucker Carlson amplified that claim Wednesday when he said 3,362 people had died after the vaccine.

But someone dying after the vaccine doesn’t mean they died because of the vaccine.

More than 4,000 reports of deaths have been reported to VAERS since December. However, the CDC has not established that any deaths have been associated with the vaccine aside from the three deaths possibly linked to the J&J vaccine.


When a death is reported to VAERS, the CDC will follow up by contacting the person who filed the report and obtaining medical records as well as the death certificate, which specifies cause of death and the autopsy report.

The CDC does not determine the cause of death; that role falls to the state and the medical examiner where the report was filed. The CDC also relies on an advisory committee on immunization practices specifically designed to review safety data to provide recommendations to the CDC and federal partners.

Shimabukuro said the CDC does not see evidence that vaccines are causing or contributing to deaths. “To the contrary, vaccines save lives,” he said.

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