And Covid vaccine given by mouth or nose can help raise the barrier against Sars-CoV-2 contagion? For a team of scientists, it is a viable strategy, capable of reducing both disease and airborne transmission. This is the conclusion reached by the authors of a study published in ‘Science Translational Medicine’ and visible online, in which the results of a test conducted on animals with an adenoviral vector vaccine candidate are reported.
Mucosal immunity
“Currently approved Sars-CoV-2 coronavirus vaccines,” administered by injection, “are able to protect vaccinees from symptomatic infections, hospitalization, and death from Covid. However, they do not completely prevent infection,” note. scientists of the Duke Center for Human Systems Immunology and Department of Surgeryof the company Vaxart he was born in Lovelace Biomedical Research Institutewho investigated the possible role of another immunity, that of mucosa. “Strategies are needed to block transmission, which slow the spread of the virus and protect against disease,” they reason.
According to the experts “there would be a substantial advantage in the development of vaccines” with this potential. The Omicron variant, in fact, “seems more capable of avoiding vaccine-induced immunity than the Delta variant and has caused a significant winter wave of infections, creating a severe shortage of health workers” for example in the US, and considering that ” most of the world is under immunized, including all children under 5 and most 5-12 year olds, the possibility that a vaccinee with post-injection shield infection could spread the virus to non-immunized family members or community members poses a risk “. Scientists then developed a vaccine candidate and to evaluate its impact they administered it orally or intranasally to the hamsters, showing that they had “robust and cross-reactive” antibody responses.
I study
The authors induced a post-vaccination infection and observed that the orally or intranasally vaccinated hamsters had a decrease in viral RNA and infectious virus in the nose and lungs and they had fewer lung diseases than the others. The rodents were exposed in a one-way airflow chamber to be vaccinated mucosally. Those infected had lower viral RNA in nasal swab and exhibited fewer clinical symptoms than control animals. This, the study authors explain, suggests that the mucosal pathway reduces viral transmission. “Our data demonstrate that mucosal immunization is a strategy” to consider.
The reason for focusing on this ‘passage’ of the virus is soon said: “The mucosa of the upper respiratory tract is the initial site of replication of Sars-CoV-2 and the primary site of infection – the US scientists point out – And consequently the interventions that induce robust mucosal immune responses may have the greatest impact on reducing Sars-CoV-2 transmission. ” Hence the choice to explore this path. The oral adenoviral vaccines developed by the scientists were administered to over 500 people, and were “well tolerated and capable of generating robust humoral and cellular immune responses to expressed antigens.”
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