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People with blood type A might be more vulnerable to the coronavirus, while those with type O blood could be more resistant, according to a new preliminary study from China.

Researchers studying COVID-19 in its outbreak epicenter, Wuhan, and the city of Shenzhen found the proportion of type A patients both infected and killed by the disease to be “significantly” higher than those with the same blood type in the general public.

Type O patients, meanwhile, made up a smaller proportion of both those infected and killed by the virus.

“People of blood group A might need particularly strengthened personal protection to reduce the chance of infection,” wrote the researchers at the Centre for Evidence-Based and Translational Medicine based out of Wuhan.

The team, led by Wang Xinghuan, couched the study as “preliminary,” with more work needing to be done to develop concrete findings.

The research, published on Medrxiv.org, compared blood types of 2,173 confirmed coronavirus cases in Wuhan and Shenzhen with more than 3,694 healthy residents in the Wuhan area.

While 31.16 percent of Wuhan residents had type A blood, 37.75 percent of surveyed coronavirus patients at the local Wuhan Jinyintan Hospital were of the same blood type.

And of the same sample of coronavirus cases at the hospital, 25.8 percent had type O blood, compared to 33.84 percent in the general population.

The study also examined 206 patients who died from the virus, finding 85 victims, or 41.26 percent, had type A blood. Just 52 of the deaths, or about a quarter, had type O.

Scientists not involved with the study told the South China Morning Post that a much larger sample size was needed to guide medical practices.

“If you are type A, there is no need to panic. It does not mean you will be infected 100 percent,” Gao Yingdai, a researcher in the city of Tianjin, told the outlet. “If you are type O, it does not mean you are absolutely safe, either. You still need to wash your hands and follow the guidelines issued by authorities.”

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There are more than 196,000 COVID-19 cases around the globe as well as more than 7,800 related deaths.