Allergies may be associated with lower risk for Covid

Are those who suffer from rhinitis better protected against Covid than those who don’t? According to a study published in the scientific journal Thorax, it is possible that not only rhinitis, but other diseases, such as allergic asthma and atopic dermatitis, are also negatively associated with the new coronavirus. The risk of those with these allergic conditions becoming infected would be up to 38% lower, on average.

One hypothesis to explain this fact would be a lower amount of ACE2 protein (angiotensin-converting enzyme type 2) in the body of these people, used by the virus as an entry point in the invasion of human cells.

Other factors that also seem to stop Covid-19 are high fruit intake, exercise and higher educational level.

On the other hand, there are several factors that increase the risk of contracting the infection: working in contact with the public, obesity, high number of people in relation to the size of the household, among others.

Britons of Asian descent were 99% more likely to get the disease, a result consistent with other observations of greater disease severity in these people, report the authors, from the Queen Mary University of London and other UK institutions.

The study was based on the responses of an additional 15,227 people to monthly questionnaires developed by the Covidence UK consortium. This initiative aims, based on the information obtained from this large sample, to unravel the behavior of the pandemic in the United Kingdom.

Of the total number of participants, 446 had confirmed cases of Covid-19—almost 3% of the sample. From the comparison between the characteristics of those infected and those not infected, the researchers sought to establish which factors were positively or negatively associated with Sars-CoV-2 infection, that is, which could favor or prevent it, respectively.

The survey includes questions about income, ethnicity, domestic animals, number of people living at home, smoking, weight, height, medical conditions, diet, exercise, use of food supplements, among many others.

Although it has brought interesting conclusions from a statistical and epidemiological point of view, it is necessary to be careful when drawing conclusions, since an association between two phenomena does not necessarily imply causality between them.

There may be the case either of a spurious, undue correlation (there is a very strong correlation between Apple’s share price and the death of people in car and bus accidents, for example), or of a confounding variable, which actually , is related to two others (it is possible to associate coffee consumption with the onset of pancreatic cancer, but this only happens because, in fact, coffee consumption is associated with smoking, which, in turn, causes cancer).

To get an idea of ​​the size of the trouble, even taking several precautions in the analysis, the authors still found the following result: patients taking immunosuppressants would be 61% more protected against Covid-19.

This may have happened not because of the drug —since the immune system, the body’s defense against invaders, is weakened with them—, but because these people are especially careful about exposure to the virus.

There are also other possibilities of distorting reality in the analysis, such as the low representation of minority ethnic groups and the little digital literacy of the older layers of the population.

Another however is the need for a diagnostic test to consider a case actually positive; this added to the low testing coverage. Many infections may have gone unnoticed, and with them the possibility of observing other associations.

Interestingly, factors already considered risk factors based on other research and observations did not show up in the new study, such as older age, male gender and the presence of other comorbidities.

The researchers conclude that, in practice, there may not be a strong correspondence in risk factors between those who simply purchase Covid-19 and those who end up in the ICU and/or who end up dying, as already shown by studies carried out in hospitals.

“There is, therefore, an urgent need for further research to investigate the social and biological factors that may explain ethnic disparities in the risk of developing Covid-19,” the scientists write.