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How Blood is Providing Insights into COVID-19 Mysteries

Research involving blood vessels, type, and proteins may help us determine who is most likely to get sick and how severe their illness will be

Rachel Muenz

Rachel Muenz, managing editor for G2 Intelligence, can be reached at

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With World Blood Donor Day approaching on June 14, we decided to take a quick look into what early research involving blood is revealing about the COVID-19 virus.

Clotting and strokes

Though first believed to be mainly a respiratory illness, in some cases people are developing strokes, blood clots, or other symptoms such as purple toes due to infection with SARS-CoV-2, the virus that causes COVID-19. While much is still unknown about why some people develop these issues while others don’t, some research so far suggests the virus may damage blood vessels indirectly while other studies have shown the virus can infect endothelial cells in blood vessels directly.

Recent research also suggests the impact on blood vessels might explain why most children—who generally have healthier blood vessels than adults—appear to be less affected by the disease, and may inform treatments for these symptoms. For example, an observational study from Mount Sinai Hospital in New York suggests that treating such patients with blood thinners may improve their chances of survival, however researchers stress the need for a properly designed clinical trial to confirm the treatment’s effectiveness.

Could blood type predict who will get COVID-19?

Other studies involving blood have shown that blood type may play a role in how likely people are to get infected with the COVID-19 virus and how sick they will become. A study still to be peer-reviewed of 1,980 COVID-19 patients in Spain and Italy indicates that those with A positive blood are more likely to develop respiratory failure due to the disease, while those with type O blood may be less vulnerable to the virus. 

Similarly, another study from researchers in China of 2,173 COVID-19 patients from three Chinese hospitals revealed “that blood group A was associated with a higher risk for acquiring COVID-19 compared with non-A blood groups, whereas blood group O was associated with a lower risk for the infection compared with non-O blood groups.” However, that study is also yet to be peer-reviewed and the researchers stress their study is an early one with limitations.

Related Article: New Insights into Why Men Are More Susceptible to COVID-19

“It would be premature to use this study to guide clinical practice at this time, but it should encourage further investigation of the relationship between the ABO blood group and…COVID-19 susceptibility,” they state.

In US research, early results from a large ongoing study by biotechnology company 23andMe—involving 750,000 participants so far—also suggests that type O individuals are less likely to get COVID-19. Specifically, a blog post on the early data says that those with type O blood are “between nine and 18 percent less likely than individuals with other blood types to have tested positive for COVID-19” and “there appear[s] to be little differences in susceptibility among the other blood types.”

Again, it should be noted that these study results are preliminary and have not yet been peer-reviewed or published in a scientific journal, so those with type O blood should still follow public health measures to contain the virus.

Biomarkers for COVID-19 severity

In related work, another recent study published in Cell Systems on June 1 shows that proteins in blood may predict how likely people infected with SARS-CoV-2 are to develop severe forms of COVID-19. The scientists, from the UK’s Francis Crick Institute and Charité – Universitätsmedizin Berlin in Germany, found 27 possible biomarkers that could be used to determine COVID-19 severity, some of which were “not previously associated with COVID-19 infection,” they write. 

To find those biomarkers, the researchers developed “a standardized, ultra-high throughput clinical platform for serum and plasma proteomics” involving mass spectrometry that is capable of quantifying 180 samples per day at low cost. They have made the software and protocols for the platform freely available for other researchers to use.

“Our study demonstrates the value and power of robust high-throughput mass spectrometry in a global public health crisis,” the study authors write. “Very fast and reliable proteome technologies can play a vital role both in clinical classification, as well as in the rapid identification of therapeutic targets against arising infecting agents.” 

As with the other research discussed here, this study does have its limits. The work is based on a small group of 31 patients, so further research will be needed to get a better picture of how well the approach works.

With studies on antibodies in the blood of those recovered from COVID-19 also helping researchers move toward possible treatments and vaccines, it seems that blood will play a major role in helping us solve the mysteries of COVID-19 going forward.

Editor’s Note: The COVID-19 situation continues to evolve rapidly. Be sure to consult your local health authority, such as the US Centers for Disease Control and Prevention, for the latest recommendations in protecting yourself and others from infection.