1 in 4 People Experience Mild Side Effects Following COVID-19 Vaccination

April 28, 2021
Killian Meara

Killian Meara, assistant editor for ContagionLive, joined the MJH Life Sciences team in November 2020. He graduated from William Paterson University with a degree in liberal studies, and concentrations in history and psychology. He enjoys film, reading, and pretending he is a good cook. Follow him on Twitter @krmeara or email him at [email protected]

The most common symptoms were headache, fatigue and soreness at the injection site.

A recent study conducted by investigators from King’s College London has discovered that 1 in 4 people who receive either the Pfizer or AstraZeneca COVID-19 vaccine will experience mild side effects within the first 24 hours of vaccination that last around 1 to 2 days.

Symptoms include headache, fatigue and tenderness at the site of vaccination. Results from the study were published in the journal Lancet Infectious Disease.

"The data should reassure many people that in the real world, after effects of the vaccine are usually mild and short-lived, especially in the over 50's who are most at risk of the infection,” Tim Spector, lead investigator on the ZOE COVID Symptom Study said. “Rates of new disease are at a new low in the UK according to the ZOE app, due to a combination of social measures and vaccination and we need to continue this successful strategy to cover the remaining population.”

For the study, investigators analyzed data, which was gathered from the ZOE COVID Symptom Study application, which is an app for cell phones where people can report any of their symptoms.

Findings from the study found that side effects following vaccination were much lower in the real world than they were in the trials. Of those vaccinated, 25.4% suffered from 1 or more systemic side effects, in comparison to 66.2% who experienced more local side ones.

13.5% of the participants in the study reported side effects after the first dose of Pfizer and 22.0% reported them after the second dose. 33.7% reported symptoms after the first shot of AstraZeneca.

The most reported symptom was headache, followed by fatigue and tenderness at the injection site.

Additionally, the side effects were seen to be most common among people who are under the age of 55.

"Our results support the aftereffects safety of both vaccines with fewer side effects in the general population than reported in the Pfizer and AstraZeneca experimental trials and should help allay safety concerns of people willing to get vaccinated,” Cristina Menni, first author on the study said.