The researchers found 9,022 of almost 383,000 Biobank participants of European ancestry studied had two copies of the e4 variant, while more than 223,000 had two copies of a variant called “e3”. The former, the team add, have a risk of dementia up to 14-fold higher than the latter.
The team then looked at positive tests for Covid-19 between 16 March and 26 April when testing for the coronavirus was largely carried out in hospitals, suggesting the cases were severe.
The results reveal 37 people who tested positive for Covid-19 had two copies of the e4 variant of ApoE, while 401 had two copies of the e3 variant. After taking into account various factors, including age and sex, the team say people with two e4 variants had more than double the risk of severe Covid-19 than those with two e3 variants.