Nasal drops enhanced with IgA antibodies and given to mice in a lab at Karolinska Institutet in Sweden reportedly protected the animals from contracting SARS-CoV-2 infection.

According to the researchers, the nasal drops enhanced with antibodies promise to protect high-risk individuals from variants of the SARS-CoV-2 virus and, potentially, other infections.

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The researchers explained that IgA antibodies are part of the adaptive immune system and are found in mucosal membranes of the airways. When mucosal IgA is absent or in short supply, there is reportedly an increased risk of SARS-CoV-2 breakthrough infections.

While the current spate of COVID-19 vaccines primarily stimulates an IgG antibody response in the body, studies suggest that their ability to protect against new omicron variants of the virus can be limited.

As such, the researchers used genetic engineering to manufacture IgA antibodies that will bind to the SARS-CoV-2 spike protein in a similar manner to the IgG antibodies.

In the lab, the researchers administered the genetically engineered IgA antibodies via nasal drops to mice already infected with the omicron variant. The nasal drops reduced the virus load in the trachea and lungs of the infected mice. Further, the IgA antibodies reportedly created a stronger bond to the spike protein of SARS-CoV-2 and, subsequently proved more effective at neutralizing the virus versus the original IgG antibodies.

"We believe that this will be a very promising strategy, not only for COVID-19 and the new variants, but also for other infectious diseases, including influenza and other respiratory infections and gastric mucosal infections such as Helicobacter pylori, where there is no vaccine available at the moment," explained the researchers.

An article detailing the team’s findings, “Conversion of monoclonal IgG to dimeric and secretory IgA restores neutralizing ability and prevents infection of Omicron lineages,” appears in the journal Proceedings of the National Academy of Sciences.