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CDC study: COVID-19 vaccine safety monitoring data ‘reassuring’

February 19, 2021

A report early released today indicates reassuring safety profiles for COVID-19 vaccines administered to health care personnel and long-term care facility (LTCF) residents between Dec. 14, 2020, and Jan. 13, 2021.

Researchers from the Centers for Disease Control and Prevention (CDC) analyzed data on adverse events related to the first and second dose of the Pfizer-BioNTech vaccine and the first dose of the Moderna vaccine that were reported to the Vaccine Adverse Event Reporting System (VAERS) and v-safe. VAERS is the CDC’s passive surveillance system, and v-safe is a new voluntary active safety monitoring system established by the CDC for the COVID-19 vaccination program.

Between Dec. 14 and Jan. 13, 13,794,904 vaccine doses were administered. Local and systemic reactions were common. Reports of anaphylaxis for both vaccines --- 4.5 cases per 1 million --- were comparable to those reported after receipt of other vaccines.

VAERS received and processed 6,844 reports of adverse events in non-LTCF residents. Symptoms reported by the 6,326 (92.4%) individuals with nonserious adverse events included headache, dizziness and fatigue.

Of the 518 (7.6%) classified as serious, there were 35 deaths (age range: 25 to 91 years); 15 (42.9%) were women. Median interval from vaccination to death was three days. Review of information about 16 deaths indicated underlying heart disease, cancer, stroke, probable pulmonary embolism and otherwise frail health as the cause. Investigation is ongoing for the other 19 deaths.

The v-safe system enrolled 1,602,065 vaccine recipients (median age 46; range 16 to 110 years) who completed at least one smartphone-based web survey. Injection site pain, fatigue, headache, myalgia and chills were the most frequently reported local and systemic reactions for first doses of either vaccine. Reactions were more frequently reported the day after vaccination, and reactions were more frequently reported after the second Pfizer dose than the first.

There were 1,106,656 women enrolled in v-safe; 10,825 (0.68%) of female enrollees reported that they were pregnant at the time of vaccination. “V-safe will be able to provide information on vaccination during pregnancy through follow-up in the v-safe pregnancy registry,” authors wrote.

At a COVID-19 Response Team briefing today, CDC Director Rochelle Walensky, M.D., M.P.H., said she anticipates additional reports by CDC researchers on COVID-19 safety monitoring data, adding that the vaccine safety monitoring system in place is the most comprehensive in U.S. history.

“We will continue to closely monitor these events and report back as part of the data emerge,” she said. “I will reiterate the CDC is committed to monitoring vaccine safety and frequently reporting on what we know.”

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