Coronavirus pill: Researchers develop COVID-19 vaccine pill, protects against disease and transmission

An investigational COVID vaccine designed to be taken orally has been found not only to protect the host, but also to decrease the airborne transmission of the virus to the unvaccinated people. The pill-based COVID vaccine has shown promise in preliminary trials - both helping to protect against severe infections and reduce transmission in hamsters.

Dr Langel and colleagues experimented with a vaccine candidate that uses an adenovirus as a vector to express the spike protein that SARS-CoV-2 uses to gain access to cells. Adenoviruses are a broad family of some 50 viruses known to cause a wide variety of illnesses such as the common cold, conjunctivitis, gastroenteritis, bladder infection, life-threatening multi-organ diseases in the clinically vulnerable. The team developed both intranasal and oral formulations of their vaccine candidate and tested it on hamsters. An advantage of the latter is that it is easy to administer.

In studies using hamsters, the vaccine elicited a robust antibody response in blood and the lungs, the release said. The experimental vaccine works through the mucosal tissues in the nose and lungs — helping to increase the production of immunoglobulin A, the immune system’s first line of defence against pathogens. This helps to better protect the nose and lungs, thereby making it less likely that the recipient of the vaccine will transmit the virus via coughing or sneezing if infected.

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When infected with Covid, the previously vaccinated hamsters exhibited a reduced viral load and exhibited fewer signs of lung damage. The team then exposed unjabbed hamsters to their peers who had been both vaccinated, and then infected.

The team found that the unvaccinated hamsters exhibited both lower viral RNA levels and milder symptoms when infected via their vaccinated peers than those exposed to unvaccinated ones — indicating that the immunisation helped reduce transmission rates.

The team trialled an oral version of their vaccine on 35 healthy human subjects. The results revealed that the vaccine tablet was both well-tolerated and elicited strong mucosal antibody responses specific to the Covid viral spike protein. Oral methods of immunisation, the team added, “should be considered for vaccination efforts that increase global immunity to SARS-CoV-2". The study focused on the original SARS-CoV-2 virus, and new studies will be designed to test the vaccine against Omicron variants.

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In December 2021, the US FDA issued an emergency use authorization (EUA) for Pfizer’s Paxlovid tablets for the treatment of mild-to-moderate coronavirus disease in adults and pediatric patients (12 years of age and older). However, Paxlovid is not a substitute for vaccination in individuals for whom COVID-19 vaccination and a booster dose are recommended.

The US FDA has also granted EUA to Merck's COVID-19 oral antiviral, Molnupiravir. When the drug enters your bloodstream, it blocks the ability of the SARS-CoV-2 virus to replicate, Dr. Albert Shaw, a Yale Medicine infectious diseases specialist, explains. In India, the anti-viral drug Molnupiravir can be used only in an emergency, informed Union Health Minister Mansukh Mandaviya.

American biotechnology firm Vaxart is likely to begin phase-2 trials of a tablet-based Covid-19 vaccine in India soon, as part of the company's global trials. The tablets are an oral recombinant vaccine that will be administered at a gap of 28 days, and the process will be followed for six months to judge its efficacy.