IgA antibodies seem to protect unvaccinated against COVID-19, study
finds

Date:
March 24, 2022
Source:
University of Gothenburg
Summary:
Despite daily contact with COVID-19 patients early in the pandemic,
some health professionals avoided falling ill. As a new study shows,
the explanation appears to be an antidote in the immune system:
IgA antibodies to COVID-19.



FULL STORY ========================================================================== Despite daily contact with Covid-19 patients early in the pandemic, some
health professionals avoided falling ill. As a University of Gothenburg
study shows, the explanation appears to be an antidote in the immune
system: IgA antibodies to COVID-19.


==========================================================================
To understand how the immune system builds up its defenses against
COVID-19, a group of researchers at the University's Sahlgrenska Academy monitored 156 employees at five primary care health centers, belonging
to the No"tka"rnan group in the Gothenburg area, for six months.

Recruited during April and May 2020, none of them had been vaccinated
against COVID-19, and most of them met infected patients daily.

The reason why some of the staff did not contract the disease seems to
have been that IgA (immunoglobulin A) was present in their respiratory
tract. These antibodies, found naturally in the secretions of mucous
membranes in the airways and gastrointestinal tract, can protect the
body by binding to viruses and other invading organisms.

One in ten protected The results of the study, published in the European Journal of Immunology, show that a third of the care workers developed antibodies to COVID-19. These subjects fell into two distinct groups
based on antibody patterns and COVID-19 incidence.



==========================================================================
One group, who had IgA antibodies only, never succumbed to COVID-19.

Participants in the other group had both IgG antibodies and T cells,
and contracted the disease. The acquired immune system also includes IgG antibodies and T cells, which serve to recognize viruses, for example,
and protect us against them.

Those responsible for the study were, first, Christine Wenneraas,
Professor of Clinical Bacteriology at Sahlgrenska Academy, University of Gothenburg, and senior physician at Sahlgrenska University Hospital; and, second, Kristina Eriksson, Professor of Viral Immunology at Sahlgrenska Academy.

"We all have IgA. It's found on the mucous membranes, and COVID-19 is an infection that spreads via those membranes. We thought it was important
to investigate what happened when completely healthy people encountered
the coronavirus, before vaccines became available," Wenneraas says.

"Of the participants in our study, none whom contracted Covid-19 required hospitalization. A lot of other research has concerned the most seriously
ill patients, who have been hospitalized and in neediof ntensive care."
Focus on health factors The present study focused on identifying health
factors that appeared to afford protection against COVID-19. Numerous
factors were found by means of extensive questionnaire surveys, blood
tests and more. As soon as a participant had nasal congestion, a cough,
red eyes, changes in the sense of taste, or anything else that could be
an infection, they had to answer questions and undergo a PCR test.

What the subjects who neither tested positive nor fell ill had in common,
then, were IgA antibodies, which bind to the coronavirus. Being female
and having a respiratory allergy were other factors affording protection against becoming infected. However, the study provides no support for
the idea that people without antibodies against COVID-19 have protective
T cells.

"A lot of the Covid-related research has been about IgG antibodies and
T cells.

The interesting thing is that when we now examine other people's articles
and tables, we find evidence for the conclusion we've arrived at about
IgA ourselves. But it's not something those studies have highlighted," Wenneraas says.


========================================================================== Story Source: Materials provided by University_of_Gothenburg. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Viktoria Hennings, Karolina Tho"rn, Sofie Albinsson, Christine
Lingblom,
Kerstin Andersson, Christer Andersson, Katarina Ja"rbur, Rille
Pullerits, Manja Idorn, So/ren R. Paludan, Kristina Eriksson,
Christine Wenneraas.

The presence of serum anti-SARS-CoV-2 IgA appears to protect
primary health care workers from COVID-19. European Journal of
Immunology, Feb.

7, 2022; DOI: 10.1002/eji.202149655 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/03/220324104454.htm

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