A new study finds that the antibodies produced in the nose decline nine months after infection COVID-19while the antibodies found in the blood last at least a year.
Los antibodies in the nasal fluid, known as immunoglobulin A or IgA, provides a frontline defense against covid by blocking the SARS-CoV-2 virus when it first enters the respiratory tract. These antibodies are very effective in preventing the virus from entering cells and causing an infection.
However, the researchers found that the nasal antibodies were only present in recently infected people and were particularly short-lived against the omicron variant, compared to earlier variants.
These new results, which are published in and Biomedicineit may explain why people who have recovered from covid are at risk of reinfection, and particularly with omicron and its subvariants.
The study also found that vaccination was very effective at creating and boosting blood antibodies, which prevent serious disease, but had little effect on nasal IgA levels.
The first author of the study, Dra. Felicity Liewfrom Imperial College London’s National Heart and Lung Institute, said: ‘Before our study, it was unclear how long these important nasal antibodies lasted. Our study found immune responses that were durable after infection and vaccination, but these key nasal antibodies were shorter lived than those in the blood.While blood antibodies help protect against disease, nasal antibodies can prevent infection altogether.This could be a major factor behind repeated infections with the SARS- virus CoV-2 and its new variants”.
The researchers note that direct work on studying these antibodies and nasal reinfections is needed to confirm their findings.
Effect of vaccines
The study also found that while current vaccines are effective at raising blood antibodies, which can prevent serious illness and death, they do not significantly raise nasal IgA antibodies.
Researchers are calling for the next generation of vaccines to be included nasal sprays or inhaled vaccines which target these antibodies more effectively. They say vaccines that can boost these antibodies could potentially reduce infections more effectively and prevent transmission.
The co-senior author of the study, Prof Peter Openshawfrom Imperial College London’s National Heart and Lung Institute, said: ‘Our findings highlight the need for nasal spray vaccines that can stimulate these local antibodies in the nose and lungs. Such vaccines could prevent people from becoming infected from the SARS-CoV-2 virus and reduce person-to-person transmission of the virus. This could help us better control the pandemic and prevent the emergence of new variants.”
He continues: “Our current vaccines are designed to reduce severe disease and death and are extremely effective for this purpose. It is now essential to also develop nasal spray vaccines that can provide better protection against infection. It’s great that current vaccines are making fewer people seriously ill, but it would be even better if we could stop them from getting infected and spreading the virus.”
The study looked at participants’ antibodies to figure out how long nasal antibodies lasted, compared to antibodies found in the blood. They also studied the effect of subsequent COVID-19 vaccines on antibodies in the nose and blood.
Samples were taken when people were admitted to hospital and six months and a year later. Since most people were vaccinated during the study, many samples were also taken before and after vaccination.
The co-lead author of the study, Dr. Lance TurtleSenior Clinical Lecturer at the University of Liverpool and infectious disease consultant at Liverpool University Hospitals, said: ‘Our study suggests that this first-line defense immunity is separate from other immune responses. vaccination and infection, it only lasts about nine months. However, booster injections can increase it slightly and otherwise have a significant impact on other areas of immunity, very effectively protecting against serious illness and death, so they remain very important.”
