People with blood type O appear to have a greater form of protection against coronavirus compared to those with other blood types, early data produced by a US genomics firm suggests.
More than 750,000 individuals have so far participated in an ongoing study conducted by 23andMe, the California-based company best known for direct-to-consumer genetic testing, which is examining the genetic make-up of SARS-CoV-2.
The preliminary data, which has not been peer-reviewed, shows that people with type O blood were on average 14 per cent less likely than other blood types to get Covid-19 and 19 per cent less likely to be hospitalised, after accounting for age, sex, ethnicity and co-morbidities.
These findings reflect similar results from other studies that have shown people with type O blood seem to report fewer incidents of infection and severe illness.
Among respondents to the 23andMe survey, the proportion of respondents reporting a positive test for Covid-19 was highest among those with the AB blood type.
The company is still recruiting for its study, and is currently seeking 10,000 participants who have been diagnosed and hospitalised with Covid-19.
In March, researchers at the Zhongnan Hospital at Wuhan University examined blood group patterns of 2,173 people who had been diagnosed with the disease and found patients with blood type A had a “significantly higher” rate of infection.
Lead researcher Wang Xinghuan said people with blood type A may need “particularly strengthened personal protection” to keep their chances of infection lower, and infected patients with that specific blood type may need “more vigilant surveillance and aggressive treatment”.
More recently, Italian and Spanish scientists noted that the gene region which codes for blood type is associated with elevated levels of key immune molecules.
In their study, which was published earlier this month, DNA samples were extracted from 1,980 patients in hotspot sites such as Milan and Barcelona who were hospitalised for respiratory failure. Their analysis showed a higher risk for A-positive individuals and a protective element among blood type O.
Research conducted into the 2002 SARS epidemic supports the O blood type protection theory for the two coronaviruses.
Scientists at a Hong Kong hospital analysed an infected patient who came into contact with 45 healthcare workers. Of 18 people with type blood O, eight became infected (44 per cent), compared to the other 27 people having other blood types, of whom 23 contracted the virus (85 per cent, or almost twice as much).
Blood type can influence blood clotting – one of the pathologies seen among seriously ill Covid-19 patients. People with type O blood have lower levels of proteins that promote blood clotting.
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