People with food allergies are less likely to get SARS-CoV-2. People who are obese become infected more often, and children—often without symptoms—can be particularly effective at spreading disease, according to scientists in the Journal of Allergy and Clinical Immunology.
The Human Epidemiology and Response to SARS-CoV-2 Study (HEROS), funded by the National Institutes of Health, found that people with food allergies were less likely to be infected with the SARS-CoV-2 virus that causes COVID-19. People without sensitivity.
Previous studies have already found that obesity is a risk factor for severe COVID-19 infection. In the HEROS study, researchers found a strong linear relationship between body mass index (a measure of body fat based on height and weight) and the risk of SARS-CoV-2 infection. And every 10-point increase in the BMI percentage increases the risk by 9%. Participants who were overweight or obese had 41 percent. A greater risk of infection than those who are not overweight.
More research is needed to explain these results. For example, analyzes of gene expression in cells from nasal swabs of participants before and after SARS-CoV-2 infection were planned. These could provide clues about the inflammatory environment associated with the infection, which researchers believe may change as BMI increases.
Additionally, it turns out that children 12 years of age or younger are just as likely to contract the virus as teens and adults (study participants had an approximately 14% chance of contracting SARS-CoV-2 during the six-month monthly follow-up period). Infection was asymptomatic in 75 percent. Children 59% adolescents and 38 percent. grown ups. in 58 percent. Participating families in which one person contracted SARS-CoV-2 was transmitted to multiple family members.
The amount of SARS-CoV-2 detected in nasal swabs (viral load) differed significantly between study participants in all age groups. The range of viral load in infected children was similar to that in adolescents and adults. A greater proportion of children with high viral loads may be asymptomatic than adults with high viral loads.
The authors concluded that young children can transmit SARS-CoV-2 very effectively at home because of the high rate of asymptomatic infection, potentially high viral loads, and close physical interactions with family members.
Dr. Anthony S. said: D., MD, director of the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health. “In addition, the observed relationship between food allergy and risk of SARS-CoV-2 infection, and between body mass index and this risk deserves further study.”
The HEROS research team monitored SARS-CoV-2 infection in more than 4,000 people in nearly 1,400 households in which at least one person was 21 years old or younger. The study was conducted in 12 US cities between May 2020 and February 2021, before COVID-19 vaccines became common in the United States and before the widespread emergence of worrisome variants. Participants were recruited from current NIH-funded research focused on allergic diseases. About half of the participating children, teens, and adults reported a food allergy, asthma, eczema, or allergic rhinitis.
Participants’ nasal swabs were collected every two weeks in each household for SARS-CoV-2 testing. Weekly surveys were also completed. If a family member has symptoms consistent with COVID-19, additional nasal swabs will be collected. Blood samples were also collected periodically and after informing the family of the disease, if any.
When the HEROS study began, preliminary evidence from other studies indicated that allergic diseases may reduce susceptibility to SARS-CoV-2 infection. The HEROS researchers found that reporting a food allergy to a doctor was associated with a halved risk of infection, but asthma and other controlled allergies — eczema and allergic rhinitis — were not associated with a reduced risk of infection.
Since all of these allergies are self-reported, the HEROS research team analyzed the levels of immunoglobulin E (IgE) antibodies, which play a key role in allergic diseases, in blood collected from a subset of participants. According to the researchers, measurements of food sensitivity and IgE of food allergens confirmed the accuracy of reported food allergies among HEROS participants, with participants who reported having a food allergy three times more often than those who did not report a food allergy. . .
The authors speculate that the inflammatory lesions characteristic of allergic conditions may reduce the level of a protein called ACE-2 receptor on the surface of airway cells. SARS-CoV-2 uses this receptor to enter cells, so its deficiency may limit the virus’s ability to infect cells.
Differences in risk behavior among people with food allergies, such as eating less frequently in restaurants, may also explain the lower risk of infection in this group. However, based on fortnightly assessments, the research team found that in the families of participants with food allergies, exposure levels were only slightly lower than in the other families.
More details – in the source post (DOI: 10.1016 / j.jaci.2022.05.014).