Thrombosis, Thrombocytopenia Syndrome Up After Ad26.COV2.S

FRIDAY, Jan. 28, 2022 (HealthDay News) -- The rate of thrombosis with thrombocytopenia syndrome (TTS) is higher after receipt of the Ad26.COV2.S vaccine than mRNA-based COVID-19 vaccines, according to a case series published online Jan. 18 in the Annals of Internal Medicine.

Isaac See, M.D., from the U.S. Centers for Disease Control and Prevention COVID-19 Response Team in Atlanta, and colleagues present surveillance data and reporting rates of all TTS cases after COVID-19 vaccination from Dec. 14, 2020, through Aug. 31, 2021, reported to the U.S. Vaccine Adverse Event Reporting System.

The researchers found that 57 TTS cases were confirmed after vaccination with Ad26.COV2.S or an mRNA-based COVID-19 vaccine (54 and three, respectively). The reporting rates were 3.83 and 0.00855 per million vaccine doses for Ad26.COV2.S and mRNA-based COVID-19 vaccines, respectively. For patients with TTS after Ad26.COV2.S, the median patient age was 44.5 years; 69 percent were women. Two of the three TTS cases after mRNA-based COVID-19 vaccination occurred in men older than 50 years and one occurred in a woman aged 50 to 59 years. All patients with TTS after Ad26.COV2.S vaccination were hospitalized; 67 percent had intensive care unit admission. Outcomes of hospitalization included death, discharge to postacute care, and discharge home (15, 17, and 68 percent, respectively).

"See and colleagues persuasively show that there are real differences in the frequency of TTS (or vaccine-induced immune thrombotic thrombocytopenia) between the Ad26.COV2.S and mRNA vaccines, thus supporting the decision by the Centers for Disease Control and Prevention to favor the mRNA-based vaccines," write the authors of an accompanying editorial.

Several authors disclosed financial ties to the biopharmaceutical, medical device, and medical technology industries.

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