by A recent study conducted by physician-scientists at Beth Israel Deaconess Medical Center (BIDMC) and their colleagues suggests that delivering COVID-19 vaccines directly to the respiratory tract may enhance protection against the virus. The findings, published in the journal Nature, highlight the importance of inducing robust mucosal immune responses at the site of primary infection in SARS-CoV-2.
The current generation of COVID-19 vaccines, administered intramuscularly (IM), have proven effective in preventing severe disease but offer limited protection against infection and transmission. According to Dr. Dan H. Barouch, the corresponding author of the study and director of the Center for Vaccine and Virology Research at BIDMC, this failure may be attributed to their inability to induce strong mucosal immune responses.
To investigate this possibility, Barouch and his colleagues conducted an experiment using adult rhesus macaques. The macaques were initially primed with the Ad26 COVID-19 vaccine (Janssen/Johnson & Johnson) via the IM route. After approximately a year, the animals received a booster shot. The boosters were administered via three different routes: IM, intranasal (IN), and intratracheal (IT). A fourth group received a bivalent mRNA vaccine (Pfizer-BioNTech) via the IN route, while a sham group received no boosters.
When the macaques were later exposed to a high dose of the SARS-CoV-2 virus, the researchers analyzed their immune responses by examining blood, nasal, and lung fluids. The results showed that the Ad26 booster administered via the IT route provided nearly complete protection against the virus and induced stronger mucosal immunity compared to the IN or IM routes.
Interestingly, the mRNA IN boosting was found to be ineffective. This suggests that improved formulations are necessary for the successful mucosal delivery of mRNA vaccines.
Dr. Barouch concluded that these findings demonstrate the potential of novel immunization strategies to enhance mucosal immunity and improve protection against respiratory viral infections. The study highlights the feasibility of developing vaccines that can effectively block respiratory virus infections.
The global COVID-19 vaccination campaign has already saved an estimated 20 million lives. However, the ongoing challenges posed by the virus, such as breakthrough infections and transmission, necessitate the exploration of innovative approaches in vaccine delivery. By targeting the respiratory tract, where the virus primarily enters the body, these next generation immunization strategies have the potential to provide enhanced protection against COVID-19.
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1. Source: Coherent Market Insights, Public sources, Desk research
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