An investigational Covid vaccine designed to be taken orally has been found not only to protect the host, but also to decrease the airborne spread of the virus to other close contacts. The vaccine was tested in animals; the human vaccine is designed to be taken as a pill. It works through the mucosal tissue to neutralise the SARS-CoV-2 virus, limiting infections and the spread of active virus in airborne particles.
The study, led by Duke University researcher Stephanie N Langel, PhD, medical instructor in the Department of Surgery, have been published in the journal Science Translational Medicine.
“Considering most of the world is under-immunized — and this is especially true of children — the possibility that a vaccinated person with a breakthrough infection can spread COVID to unimmunized family or community members poses a public health risk. There would be a substantial benefit to develop vaccines that not only protect against disease, but also reduce transmission to unvaccinated people,” a release from Duke University quoted Langel as saying.
Langel and colleagues — including teams from the vaccine developer Vaxart, and a clinical research non-profit, Lovelace Biomedical Research Institute — tested the vaccine candidate, which uses an adenovirus as a vector to express the spike protein of SARS-CoV-2.
In studies using hamsters, the vaccine elicited a robust antibody response in blood and the lungs, the release said. When the animals were exposed to the SARS-CoV-2 virus at high levels, prompting breakthrough infections, they were less symptomatic than non-vaccinated hamsters, and had lower amounts of infectious virus in the nose and lungs. Because of this, they did not shed as much virus through normal airborne exposures.
Unlike vaccines that are injected into the muscle, Langel was quoted as saying, mucosal immunizations increase production of immunoglobulin A (IgA) — the immune system’s first line of defense against pathogens — in the nose and lungs. These mucosal ports of entry are then protected, making it less likely that those who are vaccinated will transmit infectious virus during a sneeze or cough.
“Our data demonstrate that mucosal immunization is a viable strategy to decrease the spread of COVID through airborne transmission,” Langel was quoted as saying.
She said the study focused on the original SARS-CoV-2 virus, and new studies will be designed to test the vaccine against Omicron variants.
The study received funding support from The Bill and Melinda Gates Foundation, the release said. In addition to Langel, study authors include Susan Johnson, Clarissa I Martinez, Sarah N Tedjakusuma, Nadine Peinovich, Emery G Dora, Philip J Kuehl, Hammad Irshad, Edward G Barrett, Adam Werts, and Sean N Tucker.
PAPER: ‘Adenovirus type 5 SARS-CoV-2 vaccines delivered orally or intranasally reduced disease severity and transmission in a hamster model’, Stephanie N Langel et al, Science Translational Medicine. science.org/doi/10.1126/scitranslmed.abn6868
Source: Duke University
Newsletter | Click to get the day’s best explainers in your inbox
