In the previous researches on secondary effects of SARS-CoV-2, the correlation between the genetic mutation that increases the chance for dementia and the severity of COVID-19 was discovered. However, it is important to notice that this correlation can also be caused by non-biological factors like active SARS-CoV-2 transmission in retirement homes.

Following this discovery, the team of scientists from UK and USA decided to test if there is a connection between the variation of ApoE gene (the gene that increases the risk of Alzheimer) and the COVID-19's severity. The results revealed that people with two copies of ApoE E4 variation (such genotype multiplies the chance for Alzheimer up to 14-fold) are more likely to have positive SARS-CoV-2 test results in hospitals.

The data for the research was collected thanks to UK Biobank - a research endeavour found in 2006, that has collected and is currently observing genetic and health data on 500,000 volunteers aged between 48 and 86. This project allows scientists to predict the genetics impact on different diseases.

Out of 382 188 project participants, 9022 had 2 copies of ApoE E4, and only 37 (5.9%) of those had shown positive test results on SARS-CoV-2. The percentage almost doubles the "normal" ApoE E3 variation.

Researches assume, that ApoE E4 might not only be involved in lipid transportation but can moderate macrophage pro-/anti-inflammatory phenotypes.

The data from this research concludes that a certain gene variation increases the risk of severity SARS-CoV-2, but the further investigations on the topic are required.