EMA provides update on AstraZeneca’s COVID-19 vaccine safety issues

The Committee for Medicinal Products for Human Use (CHMP) of the European Medicines Agency (EMA) concluded Article 5(3) review on AstraZeneca’s COVID-19 vaccine (Vaxzevria)

The CHMP has concluded its further analysis of data on the risk of unusual blood clots linked to low levels of blood platelets (thrombosis with thrombocytopenia syndrome, TTS) and on the use of a second dose of Vaxzevria, reinforcing its interim opinion of April 2021. A scientific opinion on these points was requested by the European Commission following the initial reports of TTS associated with the vaccine. EMA analysed all the available data, including the latest TTS data from spontaneous reports in EudraVigilance, detailed vaccination data from Member States and an additional commissioned study of the risk of blood clots that was reviewed in detail by EMA’s safety committee (PRAC).

The evidence did not allow EMA to identify particular risk factors that make TTS more likely. Although spontaneous reports when put in relation to the exposure have suggested that the risk may be higher in women and in younger adults, and lower after the second compared to the first dose, the limitations of the way the data is collected mean that none of these differences could be confirmed.

EMA’s recommendation remains to continue giving a second dose of Vaxzevria between 4 and 12 weeks after the first, in line with the product information. There is no evidence that delaying the second dose has any influence on the risk of TTS. Where a second dose of Vaxzevria is not given, no definitive recommendations on the use of a different vaccine for the second dose can be made at present (see EMA/ECDC Joint Statement).

The CHMP’s detailed assessment report will be published shortly.