• Posted January 4, 2023

Smartwatch Study Finds No Unusual Heart Effects From COVID Boosters

COVID vaccine boosters appear to be perfectly safe for your heart, data gathered from nearly 5,000 smartwatch wearers shows.

Researchers tracked the heart health of thousands of Israeli smartwatch users, including more than 2,000 who received a booster dose of Pfizer's COVID vaccine.

The result: no lasting effect on a person's heart after they got the vaccine, compared to others who didn't.

"We saw clear and significant changes after administration of the vaccine, such as an increase in heart rate compared to the pulse rate measured before vaccination, and then we saw a return to the participant's baseline, i.e., the pulse levels after vaccination returned to their previous levels after six days," said co-researcher Dan Yamin, head of the Laboratory for Epidemic Research at Tel Aviv University.

"Hence, our study confirms the safety of the vaccine," Yamin added in a university news release.

The smartwatches were used to monitor a number of different health parameters, such as heart rate, variation in heart activity, quality of sleep and number of steps taken. The participants also filled out daily questionnaires about their health using a customized app.

"The most surprising finding was that the watches were more sensitive than the people they were monitoring. Many participants reported fatigue, headache, etc. after receiving the vaccine, and after two or three days reported that they felt normal and well," the researchers reported.

"In contrast, from examining their watches, we saw distinct changes in heart rate that continued for several more days. There were also vaccinated participants who did not report any side effects at all and yet definitely experienced physiological changes, based on data from their smartwatches," they said. "In other words, we learned that the smartwatches were more sensitive to changes in general feeling than the participants themselves."

To verify these findings, the research team also analyzed data from a quarter million members of an Israeli HMO, Maccabi Healthcare Services. They compared the baseline condition of people 42 days before they received the vaccine against their health 42 days after taking the jab.

In the study, published recently in the journal Lancet Respiratory Medicine, the researchers found no increase in serious incidents of any kind associated with vaccination.

"We did a comprehensive analysis of ... 25 unusual side effects, and we did not see an increase in their incidence among those receiving the booster. We found the vaccine to be safe to use," Yamin concluded

More information

The U.S. Centers for Disease Control and Prevention has more about COVID vaccines.

SOURCE: Tel Aviv University, press release, Nov. 18, 2022