Sore arm, headache, fever most common side effects of Covid-19 vaccine: UK study

A sore arm is the most common side effect of the Covid-19 vaccines and roughly one in four (25%) people had wider effects like fever, headache, nausea and fatigue and lasted for a day on average while two-thirds (66%) had a local reaction according to a UK study.

Fewer reactions were seen than in clinical trials, said researchers involved in the ZOE Covid Symptom Study app, reports BBC.

The researchers gave the findings after looking at the self-reported symptoms in 627,383 people who used their app in the eight days after being vaccinated.

About 34% had some "systemic" (whole-body) reaction like headache, tiredness or chills for the AstraZeneca jab. Whereas, this was only 14% after the first dose and 22% after the second for the Pfizer vaccine.

The most common of these side effects was a headache, said the study.

These findings should reassure people the after-effects of the vaccine are "usually mild and short-lived," said, Professor Tim Spector of King's College London, the study's lead scientist.

The results supported the safety of both vaccines and should "help allay safety concerns of people willing to get vaccinated," said Dr Cristina Menni from King's College London, the lead author of the paper.

However, the study did not look at what happened after a second dose of the AstraZeneca vaccine since hardly anyone had received it at the time of the study, which went up to March 10, the report also said.

Women, people under 55 and those who had a Covid-19 infection in the past were all more likely to experience side effects.