BERLIN (Reuters) – Instances of rare clotting in women aged under 60 who received AstraZeneca’s COVID-19 vaccine were 20 times higher than would normally be expected, Christian Bogdan, a member of Germany’s vaccine committee, said on Wednesday.
His comments came as the European Medicines Agency (EMA) and Britain’s medical regulator acknowledged a possible link between the AstraZeneca vaccine to rare cases of unusual blood clots with low blood platelet counts.
Most cases have been reported in women and, although very rare, their higher prevalence in a particular population group over a defined timeframe represented a “very clear risk signal”, Bogdan told an online briefing.
“We looked at how many cases occur in society as a background incidence, and compared that with cases observed between four and 16 days after vaccination,” he said.
“When you take that into account, then you come to an observed-to-expected ratio…of 20 (times higher) in women between 20 and 59 years old.”
The German committee recommended last week that people aged under 60 who had received one AstraZeneca shot should get a second dose of another vaccine.
Health experts also told the briefing, organised by the Science Media Center, that more research was needed to discover what may predispose people to clots with low blood platelet counts, and as well as the precise mechanism that leads to them.
The EMA’s review included 86 cases of clotting in the brain and abdomen in Britain and Europe, of which 18 were fatal.
The German vaccine advisory committee members saw no disadvantages or risks from younger recipients of AstraZeneca’s COVID-19 vaccine receiving a second dose of an alternative shot.
“Nobody expects from an immunological perspective that there will be a disadvantage to getting a second dose of another vaccine,” Marianne Roebl-Mathieu, another committee member, told the same briefing.
Should a second dose prove ineffective, a third could be effective, added Roebl-Mathieu. Studies involving mixing vaccine doses are under way.
(Reporting by John Miller and Douglas Busvine; editing by David Evans)