Can allergies protect against COVID 19?

Various risk factors have been identified which lead to the development of severe infection by COVID 19. A new study suggests that risk factors for developing COVID 19 infection are different from the risk factors for developing severe infection.

A study conducted in the UK, published in Thorax , has revealed that the factors responsible for the development of severe infection due to COVID are not the same as those for the development of the infection.

People of Asian or Asian-British ethnic races and those having high BMI were said to have a higher risk of developing COVID-19. Allergic conditions like asthma, eczema, hay fever were associated with a lower risk for developing COVID-19.

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How was the study done?

A population-based study was conducted, with 15,227 participants, who were monitored from May 2020 to February 2021. All participants were required to answer a questionnaire regarding symptoms of COVID-19 and any COVID tests they had taken. Information about potential risk factors was collected, including:

  • sociodemographic factors

  • occupation

  • lifestyle

  • weight

  • height

  • use of other medications

  • vaccination status

  • diet and supplements

  • long-term comorbidities

Monthly follow-up questionnaires were used to track the health of the participants involved.

What did it reveal?

During the duration of the study, 446 cases of COVID-19 were seen, indicating about 3% of the participants.

Factors linked to an increased probability of developing COVID-19:

  • overcrowded household

  • visit indoor public places

  • a recent visit to other households

  • frontline occupations (health and social care)

  • Asian or Asian-British descent

  • high Basal Metabolic Index

The first four factors stand for increased exposure to the virus, hence high BMI and Asian or Asian-British descent are significant risk factors for developing the disease.

Atopic diseases were linked to the decreased tendency of developing severe infection due to COVID. (Atopic refers to allergic diseases.)

Prof. Adrian Martineau, lead researcher and professor of respiratory infection and immunity said he was surprised by the results: "We did not anticipate that people with allergies and allergic asthma would have a lower risk of developing COVID-19 - in fact, there was a concern early in the pandemic that people with airway diseases would be at heightened risk."

"Our finding of reduced COVID-19 risk in this group may reflect lower levels of expression of ACE-2 in people with the allergic disease - since ACE-2 is the receptor for SARS-CoV-2." -Prof. Adrian Martineau.

"We saw that increased risk of COVID-19 in people of Asian ethnic origin was not explained by any socioeconomic, occupational, or comorbid factors investigated. This is an important finding, [and it] underlines the need for further research to understand reasons for ethnic differences in susceptibility to COVID-19."

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