Food allergy associated with lower risk of SARS-CoV-2 infection

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According to a study published in Journal of Allergy and Clinical Immunology.

In addition, the results of the prospective surveillance study showed that asthma did not positively or negatively affect the risk of SARS-CoV-2 infection.

The data were derived from Seibold A, et al. J Allergy Clin Immunol. 2022; doi: 10.1016 / j.jaci.2022.05.014.

“We know that the development of childhood asthma is associated with a serious early-stage respiratory viral infection and that most asthma exacerbations, both in children and adults, are related to respiratory virus infection.” Max A. Seibold, PhD, told Healio the director of computational biology and the Wohlberg and Lambert Endowed Chair of Pharmacogemics at National Jewish Health in Denver.

“This raised the question of whether there would be a similar type of response to SARS-CoV-2 viral infection,” said Seibold, who is also a professor of pediatrics at the National Jewish Health Center for Genes, Environment and Health. . “To look at it, you really have to have a longitudinal study design, where you track individuals regardless of whether they have symptoms.”

The human epidemiology study and response to SARS-CoV-2 included 1,394 households with 4,142 participants who were tested for COVID-19 by nasal swabs every 2 weeks between May 15, 2020 and May 1, 2020. February 2021. Participants also completed weekly surveys. with periodic collection of blood samples.

Risk factors for COVID-19

During the study period, 147 households (10.5%) with 261 participants (6.3%) tested positive for SARS-CoV-2, including 6.1% of children 12 years of age or younger, 6 , 7% of adolescents aged 13 to 21 years and 6.2% of adults. The likelihood of infection appeared to be similar among children (14%), adolescents (12.1%), and adults (14%).

The study found no association between the risk of infection and current asthma (adjusted HR = 1.04; 95% CI, 0.73-1.46), eczema (aHR = 1.06; CI 95 %, 0.75-1.5) or respiratory allergy (aHR = 0.96; 95%, 0.73-1.26).

“To be clear, there was no increase or decrease in risk among asthmatics, so they showed the same risk profiles as non-asthmatics,” Seibold said.

Participants with food allergy (31.1% adults, 28.7% adolescents, and 40.2% children), however, had a 50% reduced risk of SARS-CoV-2 infection (aHR = 0, 5; 95% CI, 0.32-0.81).

“People who are allergic to food have very high type 2 inflammation. In vitro, we have shown that type 2 inflammation can lower ACE 2 receptor levels,” said Seibold, as researchers noted that SARS -CoV-2 uses the ACE 2 receptor to enter cells.

“It is possible that in the airways of individuals allergic to food, the type of inflammation they have can reduce receptor levels and therefore decrease their risk of infection,” Seibold said.

Obese or overweight participants (63% adults, 14.7% adolescents, and 22.3% children) experienced a 41% increased risk of infection (aHR = 1.41; 95% CI, 1.06 -1.87), with each 10-point increase in the BMI percentile. increasing the risk of infection by 9% (aHR = 1.09; 95% CI, 1.03-1.15).

The researchers said more studies are needed to understand this association between obesity and an increased risk of infection, as they suggested that the inflammatory environment may change as BMI increases.

Meanwhile, 44.6% of infections were generally symptomatic, with 73.1% of them having at least three symptoms. While 24.5% of infections were symptomatic in children, 41.2% of infections in adolescents and 62.5% of infections in adults were symptomatic.

“There was a desire to create the study to try to understand transmission in homes with children with and without asthmatic and allergic individuals and to try to understand how common asymptomatic infection is among age groups,” he said. Seibold.

“We knew there were high rates of asymptomatic infection among children,” he continued. “But seeing the very strong linear relationship between age and the presence of symptoms was amazing.”

Domestic transmission

The researchers also found an association between exposure to a symptomatic member of the home and an 87.39-fold increase (95% CI, 58.02-131.63) in the risk of infection, while members asymptomatic offered 27.8 times (95% CI, 16-45.03). ) increased risk, no associations by age or sex.

In addition, the probability of transmission to an individual household member was 41.2% (95% CI, 32.3-49) during the first 50 days, with 88.3% of household transmissions in 14 days after the first domestic infection.

“Because we were tracking symptomatic and asymptomatic infections, we were able to see all kinds of transmissions,” Seibold said. “I think the contagiousness of the virus was much higher than people recognize.”

However, each year the increase in the average age of children or adolescents in the home was associated with a 21% decrease in the chances of being a transmitting home (adjusted OR = 0.79; 95% CI, 0 , 69-0.89).

Specifically, adolescents had a 6.15-fold increase (95% CI, 2.49-15.21) in the odds of being non-transmissive in relation to children and a 3.55-fold increase (95% CI). 95%, 1.56-8.08) in the probabilities of being non-transmitting. in relation to adults.

In addition, the researchers found no association between having a person with asthma (aOR = 0.64; 95% CI, 0.33-1.23), upper respiratory allergy (aOR = 0.71; 95%, 0.27-1.84) or eczema (aOR = 1.85; 95% CI, 0.65-5.21) in the home and transmission.

“Patients may be more comfortable in the sense that people with asthma are not at a higher risk of becoming infected than someone without asthma,” Seibold said. “There’s a lot of fear among the asthmatic community that they’re really highly susceptible.”

Households with food allergy had significantly lower chances of transmission (aOR = 0.43; 95% CI, 19-0.96).

Overweight or obese participants, however, had a 55% lower probability of non-transmission (aOR = 0.45; 95% CI, 0.25-0.82).

“It really reinforces how the big factor that plays inflammation in susceptibility to infection, both a positive and a negative effect,” Seibold said, adding that the study also highlights the highly contagious nature of the virus in various age groups, as well as on the importance of asymptomatic infection.

Researchers will then sequence the messenger RNA collected from participants’ airway epithelial cells during their fortnightly swabs, including swabs from individuals taken before, during, and after infection.

“We will analyze the responses of airway cells to infections among someone who has been symptomatically infected and asymptomatically infected. We will analyze childhood versus adolescent infection versus adult infection,” Seibold said. .

In addition, researchers will check for airway expression profiles that can predict if someone is likely to develop an infection, as well as how the airway profiles change once the infections are resolved.

“All of this is really exciting and is only possible because of the longitudinal nature of this collection,” Seibold said.

Reference:

For more information:

Max A. Seibold, PhD, can be contacted at seiboldm@njhealth.org.

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