The vast majority of reported reactions were mild, such as headache and fatigue.
In clinical trials, Pfizer and Moderna COVID-19 vaccines demonstrated low rates of serious adverse events. Now, real-world data from the first month of vaccine administration in the US confirms these data.
A new CDC report looks at numbers from VAERS, a government-monitored vaccine safety portal where U.S. health care workers are required to report adverse events after vaccination.
In a month of nearly 14 million doses of vaccine, only about 7,000 reports were sent to VAERS – 91% of them described mild events such as headaches, fatigue and dizziness.
Anaphylaxis, a vaccine reaction that has received widespread media coverage, has been shown to be uncommon: a total of 62 cases have been reported, at a rate of 4.5 per million doses – comparable to the rate of anaphylaxis with other vaccines. common.
Of the 14 million doses, 113 deaths were reported to VAERS; 78 from long-term care units and 35 outside the units – and so far, none of these deaths have been directly related to the vaccine.
The data is not entirely surprising, says William Schaffner, MD, a professor of preventive medicine and infectious diseases at Vanderbilt University Medical Center.
“The integrity of the safety assessment was better than we did for any licensed vaccine we used in the United States,” he told ABC News. Clinical trials of both vaccines have been extensive and both have shown very low rates of serious adverse reactions.
The CDC also collected patient-reported data from v-safe, a smartphone app for voluntary reporting of adverse events. Of the 1.6 million vaccine recipients who participated, most reported mild side effects such as injection site pain, fatigue, headache and chills. These symptoms were reported to be most prominent on the first day after injection – and worse with the second dose – but improved each subsequent day, disappearing on day 3 or 4.
The app also collected pregnancy status data, and the nearly 11,000 women who reported being pregnant will be tracked in a dedicated registry.
CDC data is limited because it relies heavily on self-reported data. For example, in both VAERS reports and v-safe reports, most adverse events were observed in women. But, as Schaffner describes, this does not necessarily mean that women are more prone to reactions.
“I’m more inclined to think it’s a reporting bias,” he said, describing the well-documented difference in the use of health care between men and women. Women are more likely to seek medical attention and more likely to report the disease.
Those who thought the pace of vaccine launches was too hasty can be sure of CDC reports, says Schaffner.
“Now that we have very well analyzed data, from a truly comprehensive range of surveillance systems, we can go beyond very large studies and say, look, we’re doing this in the real world, among your friends and neighbors,” he said. “This vaccine continues to be very, very safe.”
Eric Silberman, MD, a resident physician in internal medicine at Northwestern Memorial Hospital, is a contributor to the ABC News Medical Unit.