Europe’s drug regulator on Wednesday refrained from making any recommendations on mixing schedules of Covid-19 vaccines with doses from different manufacturers, saying it was too early to confirm if and when an additional booster shot would be needed.
However, the European Medicines Agency (EMA) did say both doses of two-shot coronavirus vaccines, such as those from Pfizer, AstraZeneca and Moderna, are needed to protect against the fast-spreading Delta variant.
In a bid to tackle increasing infections and vaccine shortages, countries are testing whether giving a different second dose to the first could boost immunity in people and bridge the gap between vaccine availability.
EMA made no definitive recommendations on switching up doses, but advised countries to take several conditions into account.
“In order to respond to these needs and increase vaccination coverage, countries may adapt their strategies…based on the epidemiological situation and circulation of variants, and the evolving evidence on vaccine effectiveness against variants,” EMA said in a statement
Need to be prepared
An Oxford study last month found https://www.reuters.com/world/uk/immune-response-astrazeneca-shot-boosted-by-mixing-dose-schedule-with-pfizer-2021-06-28 that a mixed schedule of vaccines where a shot of Pfizer’s vaccine is given four weeks after an AstraZeneca shot will produce better immune responses than giving another dose of AstraZeneca.
The European Centre for Disease Prevention and Control (ECDC) has estimated that the Delta variant will account for 90% of strains in circulation in the European Union by the end of August.
The variant, first identified in India, has led to a surge in cases worldwide and is setting back economic recovery plans.
“We always follow the science, and the expertise and evaluation from the ECDC and EMA. But we also need to be prepared and ready if (or) when booster shots may be required,” a spokesperson for the European Commission said.
The World Health Organization said on Wednesday the Delta variant was likely to become the dominant variant globally over the coming months.
Its chief scientist on Tuesday advised individuals against mixing vaccines, saying such decisions should be left to public health authorities.
EMA has also been actively monitoring rare but serious side-effects of Covid-19 vaccines, and on Wednesday disclosed it had assessed nine cases of immune thrombocytopenia (IT) following vaccination with Moderna’s shot.
While it said no “clear causal relationship” could be established between the two, EMA would continue to monitor cases, stressing that benefits of the vaccine continues to outweigh risks.
EMA in March began a review of IT, an auto-immune condition with low blood platelet levels that can lead to bruising and bleeding in people who had received the AstraZeneca, Pfizer and Moderna shots.
Moderna did not immediately respond to a request for comment.