Intranasal Vaccine Provides Broad Protection Against COVID-19 in Animal Study

Currently, COVID-19 vaccines are administered intramuscularly. They generate strong immunity in the blood but don't produce as much mucosal antibody response in the nose and airways. As a result, they are effective in preventing severe illness and death, but not as efficient in stopping infection and transmission.

Now, an intranasal vaccine candidate has demonstrated induction of local and systemic immunity against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants of concern in rodent models.

Results of this trial were published in PNAS, the journal of the National Academy of Sciences, in October 2023.

Studies indicate that intramuscular vaccine administration may not effectively generate antibodies and T cells against SARS-CoV-2 in the respiratory tract mucosa. COVID-19 vaccines have other limitations as well, including short duration of protection and high costs of production and distribution. Consequently, a need remains for better vaccines.

Vaccines that produce a strong immune response in the respiratory tract are ideal for respiratory illnesses. To prevent infection and spread, it is believed that blocking SARS-CoV-2 in the nose is the best approach.

The new study was conducted by Jianrong Li, D.V.M, Ph.D., and colleagues at the Department of Veterinary Biosciences at The Ohio State University in Columbus, Ohio. The investigators modified the MMR vaccine to create an intranasal vaccine candidate containing three stabilized prefusion spike proteins from three different SARS-CoV-2 strains.

Demonstrated were mice and hamsters immunized with a trivalent measles-mumps-SARS-CoV-2 spike protein vaccine (MMS) that developed high levels of neutralizing antibodies against SARS-CoV-2 variants. Hamsters immunized with the vaccine were completely protected when challenged with the original strain as well as the Delta and Omicron BA.1 variants.

The vaccinate candidate is based on the measles, mumps and rubella (MMR) vaccine platform, which has a 50-year track record of safety and effectiveness. Currently, the MMR vaccine is given via subcutaneous or intramuscular injection. Intranasal delivery would offer next-generation benefits such as needle-free administration and induction of mucosal immunity.

Authors wrote: “Intranasally delivered MMS induced strong SARS-CoV-2-specific neutralizing antibody, mucosal IgA, and systemic and lung resident T cell immune responses that provide broad protection against challenge with each of these three strains. Therefore, MMS is a highly promising next-generation vaccine candidate against COVID-19.”

The research was funded by was supported by grants from the National Institutes of Health, the National Cancer Institute and the Ohio State University College of Veterinary Medicine.