An interesting, observational study in the UK suggests that the overactive immune system associated with allergic diseases such as asthma and hay fever may have a positive side-effect in the form of greater protection from COVID-19 in the initial stages.
The 10-month study, involving around 15,000 people, was carried out between May 2020 and February of this year, and checked how many, and what kind of, respondents ended up getting COVID during the period.
The study, published in medical journal Thorax, then tried to associate various conditions and factors associated with each of these individuals with the chances of their contracting the disease.
It should, however, be clarified that the study did not do exhaustive COVID-19 testing on the respondents throughout the period, and had to depend on infections reported by the respondents. In other words, people who may have had symptom-less COVID are likely to have been counted in the ‘did not get COVID’ category.
What the study did do is count all the symptomatic cases of COVID within the group of nearly 15,000 people over the ten-month period.
Out of this sample size, 446 — or around 3% — were detected as having contracted COVID during the 10-month period, of which 32 were reported to have been admitted to hospital.
Surprisingly, it found that people who suffered from allergic diseases had a 23-38% lower chance of getting COVID — with the highest ‘protection’ (38%) seen in case of people who had both asthma as well as another allergic disease such as eczema and hay fever.
Those who had an allergic disease, but not asthma, still have a 23% lower chance of getting COVID.
The actual reason why this happened has not been speculated upon by the researchers, who pointed out that the study was merely an observational one and did not take blood samples and so on.
However, two of the possible reasons are: 1) the hyperactive and over-stimulated immune system among allergy patients may have done a better job of detecting and beating back the virus as soon as it entered the body, or 2) people with allergies may be taking extra precautions against COVID, which may be behind the lower number of COVID infections in this group.
It should also be noted that the report did not counter the accepted wisdom that people with asthma are more likely to have severe outcomes from COVID than others. According to the CDC website, people with moderate to severe asthma are more likely to end up in the hospital if they get COVID-19.
In other words, while an overactive immune system may help you nip the virus in the bud, it is of little use once the virus has overcome the body’s initial defences and established itself. Hence, noted the researchers, the risk factors of getting COVID and it turning serious do not appear to be the same.
“This large, population-based prospective study shows that there is limited overlap between risk factors for developing COVID-19 versus those for intensive care unit admission and death, as reported in hospitalized cohorts,” said the study.
The study also found that people of Asian descent in Britain are twice as likely to contract COVID compared to whites.
Other factors that seemed to increase the risk of contracting the disease are overcrowding, visiting or hosting other households in the preceding week, visiting indoor public places such as supermarkets, obesity and working in a people-facing role.