Rates of anaphylaxis following COVID-19 vaccination have dropped or remained stable, and all-cause mortality rates following vaccination appear to be much lower than background rates, according to research presented at the Advisory Committee on Immunization Practices (ACIP).
Tom Shimabukuro, MD, of the CDC, presented data showing that rates of anaphylaxis “have come down substantially” for the Pfizer/BioNTech vaccine compared with initially reported data. CDC data in early January found a rate of 11.1 per million doses administered, while the most recent data as of January 18 found the rate was 5.0 per million.
Rates of anaphylaxis for the Moderna vaccine remained “comparable,” at 2.8 per million, compared with 2.5 per million from CDC data last week.
Overall, 50 cases of anaphylaxis among Pfizer/BioNTech vaccine recipients and 21 among those getting the Moderna product were reported to the Vaccine Adverse Event Reporting System (VAERS) as of January 18. Median patient age in these cases was 39, and nearly all were among women, though women received 60% of COVID-19 vaccine doses.
Median time to symptom onset was 10 minutes, with most reporting symptom onset within 30 minutes, though there were a handful of cases occurring at 34, 54, 90, and 150 minutes after vaccination, and one outlier at 20 hours later. Most had documented history of allergies or allergic reactions, and about a quarter had history of prior anaphylaxis.
Shimabukuro also reported the first data on all-cause mortality following COVID-19 vaccination, which was substantially lower compared with expected and background mortality rates. Of the 196 deaths reported to VAERS due to any cause, median age was 79, 46% were women, and two-thirds were residents of long-term care facilities.
CDC researchers examined deaths in long-term care facilities, applying them to a model looking at the estimated background mortality rate, and found that of the approximately 1.3 million residents vaccinated, 11,440 deaths among residents would have been expected in the time following vaccination due to chance alone. By comparison, VAERS received 129 reports of deaths.
A separate report from the Brown University School of Public Health also concluded, “short-term mortality rates appear unrelated to COVID-19 vaccinations in residents,” Shimabukuro said.
Patients in long-term care facilities were a median age of 81, half were women, and a third were in hospice and had do-not-resuscitate or do-not-intubate orders. Of the 18 with information available, causes of death were mostly heart disease, conditions associated with aging, or dementia.
Shimabukuro said CDC researchers did a similar model comparing sudden cardiac death for adults ages 65 and younger, and found an expected sudden cardiac death count in the time following vaccination of 168, while the reported VAERS sudden cardiac death count following COVID-19 vaccination was 18.
Of the 28 patients younger than age 65, median age was 54, and 43% were women. Of those with information available, most died of heart disease, drug overdose, or COVID-19-related causes.
Both vaccines had similar rates of reactogenicity. Pain, fatigue, and headache were the most common symptoms, with reports “anywhere from 2-fold to 3-fold higher” after the second dose compared with the first dose, similar to what was reported in clinical trials, Shimabukuro said.
Rates of non-serious adverse events and serious adverse events were comparable to other vaccines. No safety signals indicating disproportionate adverse event reporting for COVID-19 vaccines were reported as of January 22.
As of January 20, about 2 million registrants out of 21 million individuals receiving at least one dose of vaccine completed at least one V-Safe post-vaccination check-in. In addition, 15,000 pregnancies were reported, though Shimabukuro noted some of those may be due to user error, such as checking the wrong box. There are currently 227 people with pregnancies enrolled in active COVID-19 safety surveillance through V-Safe, as of January 22.
The committee was also surprised by a virtual visit from new CDC director, Rochelle Walensky, MD, who praised their work, and their “important, independent role” in reviewing the data “before we give vaccines to the American public.”
“Up until a month ago, I was a practicing infectious diseases physician, I relied on ACIP throughout my career and am proud to call many of you my colleagues and friends,” Walensky said.