Study links respiratory illness during Covid to blood groups

OUTBREAK Those with blood group A+ may be most vulnerable; those with O are relatively safe

Blood groups may be a key factor in making people susceptible to developing severe respiratory problems during a Covid-19 infection, according to a study of 1,600 patients in hot spot cities in Italy and Spain that suggested those with blood group A positive were most at risk while those with O were protected to some degree.

The study, published on preprint server medrxiv, is yet to be peer reviewed. The researchers carried out a genome-wide association analysis to determine what genes were common among those that developed a severe respiratory illness after being infected by Sars-cov-2.

The researchers detected at least a couple of significant “associations”, including one that “located at the ABO blood group locus and a blood-groupspecific analysis showed higher risk for A-positive individuals and a protective effect for blood group O”, they said in the paper. The ABO blood group locus refers to a set of genes that determine which blood group an individual has.

The study could offer scientists more insight into why the disease behaves unpredictably across humans: the symptoms range from being virtually nonexistent, resembling a flu, or, in most severe cases, leaving people unable to breathe.

“Respiratory failure is a key feature of severe Covid-19 and a critical driver of mortality, but for reasons poorly defined affects less than 10% of Sarscov-2 infected patients,” the researchers said.

The variations in symptoms have often defied age and gender trends that largely suggest older men may be more vulnerable to the virus. There have been a signumber nificant number of young people who have succumbed to the illness.

The study covered 1,610 patients from hot spot cities in Italy and Spain who had developed severe symptoms after contracting the virus. The team of researchers included clinicians at the European Covid-19 epicentres in Italy and Spain and available German and Norwegian scientists. The analysis also used samples from 2,205 blood donors with no evidence of a Covid-19 infection for the genomic comparison.

The researchers noted that their findings corroborate publicly available results from the Covid-19 Host Genetics Consortium, where similar associations have been noticed among Covid-19 affected cases versus a population-based sample.

The findings in connection with the blood groups also associate with another Covid-19 symptom seen among people who develop serious illness: blood clotting. “Genetic variation at the ABO locus has previously been associated with a of procoagulant markers such as von Willebrand factor and Factor VIII, and the potential relationship between our genetic findings and the significant coagulopathy that is observed in severe Covid-19 warrants further attention,” the researchers wrote.

Genome-wide association studies are among the key strategies researchers deploy to understand a disease. The genome, simply put, determines how a human body is made up at a cellular level and the functions it carries out, whether to make or repair new cells.

These findings could help efforts to tailor therapies that at present are only mildly effective in treating Covid-19 patients.

“There is usually a strong relationship between blood group and disease. But it is very difficult at this stage to determine this particular correlation unless there is a very huge study,” said Dr RN Makroo, a specialist in molecular biology. “The distribution of blood groups in population also needs to be accounted for,” he added.

For about a week since her father succumbed to the coronavirus disease (Covid-19), 27-year-old Delhi resident Shipra Ujjainwala has made dozens of phone calls to helplines, approached multiple private testing centres, and approached at least one government hospital to be tested for the coronavirus infection.

Ujjainwala has no symptoms but she needs a “negative” certificate to get back to work and address the misgivings of her neighbours and relatives who have avoided the family for weeks.

“I was refused as I didn’t have prescription from a doctor for I had no symptoms. The fact that I had a Covid death in my family and that my organisation demands a Covid-free certificate was not enough to agree them to test me. Nobody wants to see us because of our Covid positive case history how am I supposed to get a prescription,” she said.

Her experience captures the convoluted protocols that make it difficult for even at-risk people to be able to get a Covid-19 test, complicating efforts to determine the size of the outbreak. Till Tuesday, Ujjainwala would have qualified for a test but the rule has now been changed to allow only symptomatic close contacts of a confirmed patient.

The number of Covid-19 tests carried per million people in India is a little over 3,100, a number that experts have said is inadequate to determine the true extent of the problem in the country, even as the total infections rose by another 9,962 nationally.

“Our (India’s) condition may be worse than Italy, but we don’t know since we aren’t testing enough. We don’t acknowledge our real status in terms of disease spread because it seems our focus is largely on proving we are doing better than other countries in managing the disease. We have tested about 3.9 million people from a population of 1.3 billion, which is roughly about 0.3% of the population. How can you plan how to control a pandemic for the rest of the 99.7% of the population by merely looking at the results in 0.3% of the population?” said Dr T Jacob John, former virology head, Christian Medical College, Vellore John.

The problem is not merely that the rules are restrictive but that they are also changing rapidly.

“There is perpetual confusion over who to test, as the government keeps changing guidelines. It feels like harassment and it appears they want private labs to stop testing by making it difficult for us to operate,” said the owner of a private laboratory owner, asking not to be named.

Representatives of the Indian Council of Medical Research – the apex body that sets the standards for such protocols across the country (though they can be tweaked by states) – said the changes are due to evolving demands. “ICMR has been time to time revising guidelines as per what the situation demands. The protocols have been clearly laid out that states should follow. Some states are perhaps going by their own rules by making additions or to ICMR protocol that is probably creating problems,” said Dr Rajnikant Srivastava, spokesperson, ICMR.

Manufacturers of test kits say they are prepared to meet higher demands.

In the last two days, the number of daily tests in country was more than 135,000. “We are currently producing 2 lakh tests a day; there is absolutely no shortage of kits. I can say for sure that in some time India is going to be a competitive market globally,” said Hasmukh Rawal, managing director, Mylab Discovery Solutions, Pune-based manufacturers of RT-PCR diagnostic kits.

Current bottlenecks, however, could be in the labs.

“There is no shortage of kits and equipment but there is only a particular number of tests that a laboratory can do, which is the testing capacity of a lab. You cannot go beyond that, no matter how many extra kits you have. It is not possible to test the entire 1.3 billion population,” said Dr Srivastava.

THE STUDY COULD OFFER SCIENTISTS MORE INSIGHT INTO WHY THE DISEASE BEHAVES UNPREDICTABLY ACROSS HUMANS 12 TEST COVID +VE