麻豆传媒

Rates of syncope, or fainting, following administration of Johnson & Johnson's COVID-19 vaccine were significantly higher than rates following influenza vaccination, researchers found.

Examining all reports of syncope following Johnson & Johnson vaccination submitted to the Vaccine Adverse Event Reporting System (VAERS), the anxiety-related event occurred at a rate of 8.2 episodes per 100,000 doses, while the rate after influenza vaccination was 0.05 episodes per 100,000, said Anne Hause, PhD, of the CDC, and colleagues, in an early edition of the

Five different mass vaccination clinics reported 64 anxiety-related events, including 17 cases of syncope, among 8,624 Johnson & Johnson COVID-19 vaccine recipients from April 7 to 9.

An anxiety-related event was defined as occurring during the 15-minute post-vaccination observation period. Other anxiety-related symptoms included tachycardia, hyperventilation, dyspnea, chest pain, paresthesia (numbness or tingling), lightheadedness, hypotension, headache, and pallor.

Of these 64 cases, 61% occurred in women, and median patient age was 36.

The most common symptoms were lightheadedness or dizziness (56%), pallor or diaphoresis (31%), and syncope (27%). Notably, 13 patients said they had a history of fainting associated with injections or a needle aversion. Most cases resolved within 15 minutes with supportive care, although 13 patients were transported to an emergency department. Of the five for whom information was available, all were released the same day.

Hause and colleagues noted that four of the five sites temporarily suspended COVID-19 vaccination, and none of the events at the five sites were judged to be serious.

The team then broadened their search, examining all reports of syncope following the Johnson & Johnson vaccine submitted to VAERS from March 2 to April 11. They found 653 eligible reports out of 7.98 million doses administered. Half were among women, with a median age of 30. The largest proportion of these adverse events occurred in women ages 18-29.

Among these reports, 3% were classified as serious. Nineteen percent of patients reported a history of syncope tied to receiving injections or needle aversion.

They compared this rate to the rate of syncope following influenza vaccination from July 1, 2019 to June 30, 2020, for which 60 cases were reported among 124 million doses.

Hause and colleagues cautioned that while these events were submitted prior to the pause in Johnson & Johnson COVID-19 vaccination from April 13 to 23 following reports of thrombosis with thrombocytopenia syndrome (TTS), "anxiety-related events, including syncope, occurring soon after COVID-19 vaccination could raise concern among other vaccine recipients and staff members, particularly in a mass vaccination setting."

More Non-CVST Cases of Rare Clotting Condition

A second report examined all adverse events related to the Johnson & Johnson COVID-19 vaccine that were reported to VAERS from March 2 to April 11. Of 13,725 reports, only 3% were judged to be serious. Those 343 reports included three cases of non-cerebral venous sinus thrombosis (CVST) TTS, reported David Shay, MD, of the CDC, and colleagues.

Two of these cases occurred in women ages 30-39, and one occurred in a woman age 50-59. All had evidence of large-vessel thrombosis and thrombocytopenia.

They noted that, as of April 25, this brought the total cases of TTS to 17, including 14 cases of CVST. As previously reported, three patients with CVST died.

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