HealthDay News — Systemic and local side effects to Pfizer-BioNTech and Oxford-AstraZeneca COVID-19 vaccines occur at relatively low frequencies, according to a study published online April 27 in The Lancet Infectious Diseases.

Cristina Menni, PhD, from King’s College London, and colleagues conducted a prospective observational study to examine the proportion and probability of self-reported systemic and local side effects within 8 days of vaccination among individuals receiving 1 or 2 doses of the Pfizer-BioNTech COVID-19 vaccine or 1 dose of the Oxford-AstraZeneca COVID-19 vaccine.

A total of 627,383 individuals reported being vaccinated with 655,590 doses between December 8, 2020, and March 10, 2021. The researchers found that systemic side effects were reported by 13.5% and 22.0% of individuals after the first and second doses of Pfizer-BioNTech COVID-19 vaccine, respectively, and by 33.7% after their first dose of Oxford-AstraZeneca COVID-19 vaccine. Local side effects were reported by 71.9% and 68.5% after the first and second doses of Pfizer-BioNTech COVID-19 vaccine, respectively, and by 58.7% after the first dose of Oxford-AstraZeneca COVID-19 vaccine. Compared with those without known past infection, systemic side effects were more common after the first Pfizer-BioNTech and Oxford-AstraZeneca doses (1.6 and 2.9 times, respectively) among individuals with previous SARS-CoV-2 infection. Starting 12 days after the first dose, there was a significant reduction in the infection risk, reaching 60% for Oxford-AstraZeneca and 69% and 72% for Pfizer-BioNTech at 21 to 44 and 45 to 59 days, respectively.


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“Short-term adverse effects of both vaccines are moderate in frequency, mild in severity, and short-lived,” the authors write.

Several authors disclosed financial ties to pharmaceutical companies, including Pfizer and AstraZeneca, and to ZOE Global.

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