New data from the UK’s vaccination programme suggests that one in four people get Pfizer and AstraZeneca vaccine side effects – with most peaking in the first 24 hours, then gone in two days
The study by King’s College London looked at the UK population, which is currently using mainly Pfizer and AstraZeneca. The data was drawn from 627,383 participants, who reported their reactions to vaccination between December and March.
Side effects are one of the key reasons that some remain nervous to get their first or even second dose. But in this new data, scientists look at how the vaccines have been working in the UK to understand how serious side effects are – they found that there were fewer side effects in the population than in the original clinical trials.
If you already had COVID, are the side effects worse?
Participants who had a confirmed case of COVID were three times more likely to have side effects in their whole body after Pfizer, than participants who did not have COVID-19 previously. People who had already experienced the virus were also more likely to have tenderness in their arm.
What are the real-world side effects of the COVID vaccine?
Only 25.4% of vaccinated people said they had side effects (that were not a physical pain at the injection point), while 66.2% said they had a local, injection arm related side effect.
More people reported a side effect after the first AstraZeneca dose than the Pfizer, while the most common side effect was headache. People who took Pfizer reported that the second dose gave them a headache more than the first dose. Overall, more people had a headache after the AstraZeneca first dose than the Pfizer first dose.
The second most common side effect was fatigue. According to the data, 8.4% and 14.4% of participants reported fatigue after first and second dose of Pfizer vaccine and 21.1% reported fatigue after their first dose of AstraZeneca.
Then, the most common local side effect was tenderness. Around 57.2% and 50.9% reported this effect after first and second dose of Pfizer vaccine, and 49.3% after first dose of AstraZeneca.
Which age group has the most side effects?
This research identifies that side effects were more common among people under 55 years of age and among women, which is different to who is most impacted by COVID itself. This is a situation that has not been widely discussed in the media, leading some to panic about their side effects.
‘Effects of the vaccine are usually mild’
Professor Tim Spector OBE, lead scientist on the ZOE COVID Symptom Study app and Professor of Genetic Epidemiology at King’s College London said: “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.
“The results also show up to 70% protection after 3 weeks following a single dose, which is fantastic news for the country, especially as more people have now had their second jabs.”