COVID-19 vaccine third shot side effects on par with second dose: CDC study

Most additional doses of mRNA COVID-19 vaccine administered about six months after the primary series resulted in mild-to-moderate side effects, according to an initial analysis released Tuesday from the Centers for Disease Control and Prevention (CDC). The study period occurred when mRNA third dose eligibility was limited to patients with moderate-to-severe immunocompromising conditions.

Findings stemmed from data collected between Aug. 12 to Sept. 19 through v-safe, the CDC’s voluntary phone-based surveillance system, and included 22,191 registrants who reported receiving a third dose of vaccine.

PFIZER-BIONTECH SUBMIT COVID-19 VACCINE DATA TO FDA FOR KIDS 5-11

Nearly all registrants under study received a third dose matching the primary series, and for 12,591 registrants who completed a check-in survey, 79.4% and 74.1% reported local or systemic reactions, respectively, after the third dose, versus 77.6% and 76.5%, respectively, after the second dose.

"These initial findings indicate no unexpected patterns of adverse reactions after an additional dose of COVID-19 vaccine; most of these adverse reactions were mild or moderate," the report reads.