Prior to reports of rare but serious blood clotting with Johnson & Johnson’s COVID-19 vaccine, federal health authorities were investigating dozens of anxiety-related events and fainting episodes in vaccine recipients, according to the latest report from the Centers for Disease Control and Prevention (CDC).
In early April, four of out five mass vaccination sites across different states temporarily shuttered while the CDC analyzed 64 anxiety-related events, including 17 instances of syncope, or fainting among some 8,600 vaccine recipients. None of the reports were classified as serious, the agency said.
"[Four of five] sites providing drive-through vaccination had previously administered 1,000–4,000 mRNA COVID-19 vaccines per day without reported similar clusters of events," CDC researchers wrote.
When comparing anxiety-related events with the flu vaccine, CDC researchers noted fainting episodes were reported at a rate of 0.05 per 100,000 doses, compared to 8.2 fainting episodes per 100,000 J&J doses. The flu vaccine was used as a comparison because both are single-dose vaccines and available to all U.S. adults, compared to the two-dose mRNA COVID-19 vaccines which were rolled out among higher-tiered prioritization groups, while J&J entered the national rollout later on.
The federal health agency estimated that fainting after J&J vaccination was 164 times more common compared to the flu vaccine.
The CDC noted light-headedness or dizziness occurred in 56% of the 64 reported cases, but also excessive sweating, fainting, nausea or vomiting and, in fewer instances, low blood pressure. Women accounted for 61% of the reported cases, and most occurrences resolved with 15 minutes alongside care. Thirteen patients were transported to the hospital, and of five patients with available information, all were released on the same day.
Nearly a quarter of patients reported a needle aversion or history of fainting post-vaccination.
The CDC also analyzed all fainting reports following J&J vaccination from March to April sent to a national vaccine safety monitoring system (Vaccine Adverse Event Reporting System, VAERS), and found some 653 eligible reports, 3% of which were characterized as serious, and 19% comprising people with a needle aversion or history of fainting post-vaccination.
"Anxiety-related events, including syncope, can occur immediately after vaccination with any vaccine and might be caused by anxiety about receiving an injection," CDC researchers wrote in the report.
The CDC says younger patients typically experience anxiety-related events post-vaccination more often than older adults; in both the J&J and flu vaccine analysis, patients aged 18-29 accounted for the largest share of fainting events. In the larger national analysis, those aged 18-29 accounted for half of fainting episodes after receiving a J&J COVID-19 vaccine.
For those who loathe needles, the J&J one-shot vaccine could be a more appealing option, the agency notes, and therefore some seeking the shot would be more likely to experience anxiety-related episodes post-vaccination.
"The stress of an ongoing pandemic might also increase anxiety surrounding COVID-19 vaccination. In addition, in mass vaccination situations, an anxiety-related event witnessed by others on-site or reported through media coverage might provoke additional anxiety-induced episodes," the agency continued. "As use of COVID-19 vaccines expands into younger age groups, providers should be aware that younger persons might be more highly predisposed to anxiety-related events after vaccination than are older persons."
The agency stressed that providers should be aware of an increase in anxiety-related events shortly after the J&J jab compared to flu vaccines, and to observe all COVID-19 vaccine recipients for 15 minutes afterwards.