Several COVID-19 inhalable vaccines move to human trials

A new study in the journal Scientists progress presents the latest research demonstrating the potential effectiveness of an inhalable COVID-19 vaccine. The vaccine is one of many vaccines in development designed to be administered by nasal spray.

“The currently available COVID-19 vaccines are very effective, but the majority of the world’s population is still unvaccinated and there is a critical need for more easy-to-use and effective vaccines to stop disease and transmission.” says Paul McCray, a University of Iowa researcher working on an inhalable COVID-19 vaccine.

McCray is working alongside colleagues at the University of Georgia on a single-dose COVID-19 vaccine delivered via a nasal spray. Their particular vaccine uses a virus called parainfluenza virus 5 (PIV5), optimized to express the SARS-CoV-2 spike protein.

PIV5 is harmless in humans, and previous experiments with the virus as a vaccine delivery system have been effective in animal studies against MERS, another coronavirus. The new data shows that the experimental COVID-19 vaccine is effective in mice and ferrets.

“We have been developing this vaccine platform for over 20 years and have started working on new vaccine formulations to fight COVID-19 during the early days of the pandemic,” said the co-head of the study, Biao He, of the University. from Georgia. “Our preclinical data shows that this vaccine not only protects against infection, but also significantly reduces the risk of transmission.”

Traditional vaccines are usually given by intramuscular injection. But there are a host of obstacles with injections that make widespread immunization campaigns complicated and expensive. Injected vaccines often require a cold room and must be administered by healthcare professionals. Syringes are also a limited resource and supply issues have caused major problems with the COVID-19 vaccine go out.

A nasal spray vaccine is currently on the market. Called FluMist, the vaccine targets influenza and, although approved for about a decade, its effectiveness has varied from year to year. For several years, the American Academy of Pediatrics and the Centers of Disease Control and Prevention have recommended the injectable influenza vaccine rather than this inhalable version, but recently changed this advice after a new formulation showed improved efficacy during the 2019-2020 influenza season.

Along with the ease of administration of a vaccine by nasal spray, there is a strong hypothesis suggesting that administration of vaccines directly to the mucous tissue of the upper respiratory tract may offer better localized protection against infection. Darrell Irvine, a bioengineer at MIT, has been working on the development of inhalable vaccines for several years.

“In some cases, vaccines given to the muscles can cause immunity at the mucosal surfaces, but there is a general principle that if you vaccinate through the mucosal surface, you tend to get stronger protection at that site. “, said Irvine. “Unfortunately, we do not yet have major technologies to develop immune responses that specifically protect these mucous surfaces.”

A study by Irvine’s MIT team published earlier this year demonstrated high efficacy with a new method binding peptide vaccines to albumin proteins. Studies in mice have shown that the inhalable vaccine generates a 25-fold increase in immune T cells compared to the same vaccine injected into the muscle.

A small number of inhalable COVID-19 vaccines are currently at an early stage in human trials. In early 2021, researchers at the University of Oxford began Phase 1 human trials for a nasal spray version of its ChAdOx1 nCoV-19 vaccine (now better known as the AstraZeneca COVID-19 vaccine).

Sandy Douglas, chief investigator of the trial, said they were initially studying the safety profile of the nasal spray in healthy young volunteers. It is hoped that administration of the COVID-19 vaccine through the upper respiratory tissues might offer better protection against mild illness and subsequent transmission, but Douglas also notes that administration by inhalation should also increase absorption of the vaccine.

“There are a variety of people who will find an intranasal delivery system more attractive, which may mean that vaccine uptake is higher in these groups,” says Douglas. “It could also have practical advantages – nasal sprays have been used successfully for other vaccines, for example the flu vaccine used in British schools.”

Overall there are about seven intranasal COVID-19 vaccines currently in the early stages of human trials, but it is still unclear whether this route of administration will work effectively for SARS-CoV-2. More recently, a pharmaceutical company Altimmune has interrupted its work on its inhalable vaccine candidate after phase 1 human trials showed weak immune responses.

Richard Kennedy, an immunology researcher at the Mayo Clinic, says it seems increasingly clear that inhalable vaccines will not work for all pathogens. Several research dead ends over the past decade indicate that developing a nasal spray COVID-19 vaccine may not be a straightforward task, but hopefully research advancing at a rapid pace. , we will have answers over the next year.

“There aren’t a lot of licensed mucosal vaccines,” Kennedy recently told MedPage today. “These vaccines are effective for some pathogens, but this may or may not be true for SARS-CoV-2.”

The new study was published in the journal Scientists progress.

Source: Carver College of Medicine