Scientists believe they have found why some people contract COVID-19 many times despite having immunity from vaccination or an earlier infection.
A recent study by British researchers found that antibodies produced in the nose decrease more rapidly than blood-borne antibodies.
The research, published in eBioMedicine, also confirmed that vaccinations are highly effective at producing and increasing blood-borne antibodies, with little impact on nasal antibodies.
Researchers say the next generation of vaccines should include nasal spray vaccines that target these antibodies.
British researchers discovered the answer is in the nose.
The study, published in eBioMedicine, showed that antibodies produced in the nose decrease more rapidly than blood-borne antibodies.
The nose is understood as the first line of defense against respiratory viruses like COVID.
While antibodies in the blood last at least a year, antibodies in the nose leave about nine months after COVID-19 infection.
The research also confirmed that vaccination is highly effective at producing and increasing blood-borne antibodies. These antibodies help protect against deadly diseases, but have little impact on nasal antibodies.
“Before our study, it was unclear how long these important nasal antibodies lasted. Our study found durable immune responses after infection and vaccination, but these key nasal antibodies were shorter-lived than those in the blood,” said Dr. Felicity Liew, lead researcher from the National Heart and Lung Institute at Imperial College London.
In the study, nearly 450 COVID-19 patients who were hospitalized between February 2020 and March 2021 were analyzed. The researchers also examined the impact of future COVID-19 vaccinations on antibody levels in the nose and blood.
It is important to note that the study was conducted before the appearance of the Omicron variant and the release of COVID-19 vaccines.
The researchers examined antibodies from patients at three different times: during hospitalization, six months later, and one year later. During a follow-up, more than two-thirds of the patients received their first COVID-19 vaccine.
"Our study suggests that this first-line defense immunity is separate from other immune responses, and although it is increased by vaccination and infection, it only lasts for about nine months. Nonetheless, booster vaccines can increase it slightly and otherwise have a significant impact on other areas of immunity, protecting against severe disease and death very effectively, so remain very important."Dr. Lance Turtle, co-author of the study
The scientists acknowledge that they didn't look for reinfections when they did their analysis. However, they say that reinfection is unlikely because COVID-19 was rare during the time of the study when federal restrictions and lockdowns were in place. Also, a previous study found only two cases of reinfection, which suggests that the overall trends are correct.
Researchers are advocating for inhaled or nasal spray vaccines that specifically target these antibodies in the next generation of immunizations. They say that vaccines that could boost these antibodies may help fight infections better and stop them from spreading.
“While blood antibodies help to protect against disease, nasal antibodies can prevent infection altogether. This might be an important factor behind repeat infections with the SARS-CoV-2 virus and its new variants,” Liew added in an Imperial College news release.
Several new COVID-19 variations have been discovered in the United States and elsewhere. New laboratory data suggest that some vaccines and previous infections may not provide enough protection. New vaccines that consider these nasal antibody findings may help counter this issue.