Antibodies produced in the nose decline nine months following COVID-19 infection, while antibodies found in the blood last for at least a year, a new study finds.
Antibodies in the nasal fluid (known as immunoglobulin A or IgA) provide first-line defense once morest COVID-19 by blocking the SARS-CoV-2 virus when it first enters the airways respiratory. These antibodies are very effective in preventing the virus from entering cells and causing infection.
However, investigators found that nasal antibodies were only present in recently infected people and were particularly short-lived once morest the Omicron variant, compared to earlier variants.
These new findings – which are published in eBioMedicine – may explain why people who have recovered from COVID are at risk of reinfection, and especially with Omicron and its subvariants.
The study also found that vaccination is very effective at creating and stimulating antibodies in the blood, which prevent serious disease, but has very little effect on nasal IgA levels.
The study’s first author, Dr Felicity Liew, from the National Heart and Lung Institute at Imperial College London, said: ” Before our study, it was unknown how long these important nasal antibodies lasted. Our study found long-lasting immune responses following infection and vaccination, but these key nasal antibodies have a shorter lifespan than those in the blood. While blood antibodies help protect once morest disease, nasal antibodies can completely prevent infection. This might be an important factor behind repeated infections with the SARS-CoV-2 virus and its new variants. »
The researchers note that studies that directly investigate these nasal antibodies and reinfections are needed to confirm their findings.
The research was carried out by teams from Imperial College London and the University of Liverpool. It studied nearly 450 people who had been hospitalized with COVID-19 between February 2020 and March 2021, before the Omicron variant emerged and before the vaccine was rolled out.
The study also found that while current vaccines are effective at stimulating blood antibodies that can prevent serious illness and death, they do not significantly stimulate nasal IgA antibodies.
The researchers call for the next generation of vaccines to include nasal sprays or inhaled vaccines that more effectively target these antibodies. They say vaccines that can stimulate these antibodies might potentially reduce infections more effectively and prevent transmission.
The study’s co-lead author, Professor Peter Openshaw, of the National Heart and Lung Institute at Imperial College London, said: ” Our results highlight a need for nasal spray vaccines that can stimulate these local antibodies in the nose and lungs. Such vaccines might prevent people from becoming infected with the SARS-CoV-2 virus and reduce transmission of the virus between people. This might help us better control the pandemic and prevent the emergence of new variants. »
He keeps on: ” Our current vaccines are designed to reduce serious illness and death and are extremely effective in doing so. It is now essential to also develop nasal spray vaccines that can offer better protection once morest infection. It’s great that current vaccines mean fewer people get seriously ill, but it would be even better if we might prevent them from getting infected and passing on the virus.«
The study analyzed participants’ antibodies to understand 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 hospitalized and at six months and one year later. Since most people were vaccinated during the study, many samples were also taken before and following vaccination.
They measured how well the antibodies neutralized the original SARS-CoV-2 virus and the Delta and Omicron variants to see how long the antibodies were effective following infection or vaccination.
The study included 446 people admitted to hospital at the start of the pandemic, including 141 who provided samples at the start of the study and six and 12 months later. For participants who had only taken one sample during the 12-month study period, researchers used modeling to estimate how average antibody responses changed over time.
Of those who confirmed they had been vaccinated (323 people), 95% (307 people) received their first vaccination during the study follow-up period. This caused an increase in all nasal and blood antibodies, but the change in nasal first-line defense antibodies (IgA) was small and temporary. The researchers found that participants’ gender, disease severity and age did not affect how long their nasal immunity lasted, but cautioned that their study only involved people with the disease. severe requiring hospitalization.
They also found that participants’ blood antibodies continued to bind to the original SARS-CoV-2 virus and the Delta and Omicron variants one year following infection, but found that booster shots are needed to maintain this. immunity.
The study’s co-lead author, Dr Lance Turtle, Clinical Lecturer at the University of Liverpool and Infectious Diseases Consultant at University Hospitals Liverpool, said: ” Our study suggests that this first-line defense immunity is distinct from other immune responses, and although it is augmented by vaccination and infection, it lasts only regarding nine months. Nevertheless, booster vaccines can increase it slightly and have a significant impact on other areas of immunity, very effectively protecting once morest serious illness and death, so they are still very important.. »
The researchers note that their study did not screen participants for reinfection, but that was unlikely to have happened since the study took place during times of national restrictions and lockdowns when the incidence COVID-19 was low and people weren’t mixing. In a preliminary analysis, they found only two cases of reinfection in their study, suggesting that the overall trends observed are accurate.
The study was supported by the ISARIC4C, UKCIC and PHOSP-COVID consortia. It was jointly funded by the National Institute for Health and Care Research, UK Research and Innovation and the Medical Research Council.
