PTI | New Delhi | Updated: 28-04-2021 15:12 IST | Created: 28-04-2021 15:12 IST One in four people experience mild, short lived systemic side effects after receiving either the COVID-19 preventive by Pfizer or AstraZeneca vaccine -- known as Covishield in India -- with headache, fatigue and tenderness the most common symptoms, according to a study published in the Lancet Infectious Diseases journal. The researchers from King's CollegeLondon in the UK also found that most systemic side effects -- meaning side effects excluding where the injection took place -- peaked within the first 24 hours following vaccination and usually lasted 1-2 days. The analysis of data from the ZOE COVID Symptom Study app found much fewer side effects in the general population with both the Pfizer and AstraZeneca vaccines than reported in trials.