The study period preceded the recently expanded booster shot eligibility for adults over 65 and other high-risk groups.
Most additional doses of the mRNA COVID-19 vaccine were given approximately six months after the primary series had mild to moderate side effects, according to a preliminary analysis released Tuesday from the Centers for Disease Control and Prevention (CDC). The study period occurred when the mRNA third dose eligibility was limited to patients with moderate to severe immunocompromising conditions.
test result The vaccine stems from data collected between August 12 and September 19 through V-Safe, the CDC’s voluntary phone-based surveillance system, and includes 22,191 registrants who reported receiving their third dose of the vaccine.
Nearly all registrants under study received a matching third dose For the primary series, and 12,591 registrants who completed the check-in survey, 79.4% and 74.1% reported local or systemic reactions after the third dose, versus 77.6% and 76.5%, respectively, after the second dose.
“These initial findings indicate no unexpected pattern of adverse reactions following an additional dose of the COVID-19 vaccine, most of these adverse reactions were mild or moderate,” the report said.
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Across the board, V-SAFE data indicated a slight increase in local reactions after the third dose versus dose two, and a slight decrease in systemic reactions after dose three versus dose two. Most reports of pain following additional doses were described as mild to moderate reactions (51.4% and 41.9%), while 637 registrants (6.7%) reported severe pain, defined as “pain that makes daily activities difficult or impossible.”
Of the total 22,191 third dose recipients, about 28% said they could not perform “normal daily activities” the day after vaccination, while 1.8% sought medical care and 0.1% were hospitalized. The survey did not capture reasons for medical attention or hospitalization, although the report noted that CDC staff complied with these registrants.
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CDC Director Dr. Rochelle Valensky spoke to the findings during Tuesday’s White House briefing, which said the CDC and FDA reviewed the report in informing newly released recommendations for booster shots, which provided expanded eligibility for Pfizer vaccine boosters. Several high-risk groups after about six months of the primary series. Health officials are working to review similar data for recipients of other vaccines developed by Moderna and J&J.
“The COVID-19 vaccine booster dose is so far well tolerated,” Valensky said of the report, in part, adding, “The frequency and type of side effects were similar to those seen after the second vaccine dose and were mostly mild or moderate and short-lived.”
“We will continue to evaluate the data as it becomes available in real time and with urgency and update our recommendations to ensure that everyone at risk has the protection they need,” Valensky said.
While eligibility for the third dose was limited to a small fraction of Americans with immunocompromising conditions during the study period, researchers suspected that registrants included those with and without such conditions, and about immune status in the V-Safe Surveillance System. Data is not included.