The AstraZeneca vaccine is safe and effective at protecting people from the extremely serious risks of COVID-19, including death, hospitalization and severe disease.
Common, mild symptoms following vaccination include tenderness, pain, warmth, redness, itching, swelling or bruising where the injection is given, tiredness, headache, fever, nausea or muscle ache.
A very rare syndrome of blood clotting combined with low platelet counts, described as thrombosis with thrombocytopenia syndrome (TTS), has been reported around 3 to 30 days following vaccination with the ChAdOx1-S [recombinant] vaccine. Data from the United Kingdom (as of 14 June 2021) and the European Union suggest the risk of TTS is estimated to be approximately 1 case per 100 000 vaccinated adults.
Rare cases of Guillain-Barré Syndrome (GBS) have also been reported following vaccination with this vaccine.
WHO has reviewed all evidence on these rare events and concluded that the benefits of these vaccines in preventing severe illness and deaths far outweigh the small risks. In addition, WHO and countries are conducting research and implementing actions to mitigate further those small risks.
Health care personnel should be alert to the signs and symptoms of thromboembolism and/or thrombocytopenia. Those vaccinated should be instructed to seek immediate medical attention if they develop symptoms such as shortness of breath, chest pain, leg swelling, persistent abdominal pain following vaccination. Additionally, anyone with neurological symptoms including severe or persistent headaches and blurred vision after vaccination, or who experience skin bruising (petechia) beyond the site of vaccination after a few days, should seek prompt medical attention.
It is important to remember that serious adverse reactions are very rare and treatable when diagnosed early and that the risks are higher with COVID-19 disease than following vaccination.