A team of US scientists, including research investigator Sonali Chaturvedi, has developed a single-dose, intranasal treatment that not only reduces symptoms of multiple Covid variants but also shedding of the virus.

In a new study published in Proceedings of the National Academy of Sciences, the team from Gladstone Institutes in San Francisco showed that this new treatment, called a therapeutic interfering particle (TIP), also decreases the amount of virus shed from infected animals and limits transmission of the virus.

"To our knowledge, this is the only single-dose antiviral that reduces not only symptoms and severity of Covid-19, but also shedding of the virus," said Chaturvedi, first author of the paper.

Historically, it has been exceptionally challenging for antivirals and vaccines to limit the transmission of respiratory viruses, including SARS-CoV-2.

"This study shows that a single, intranasal dose of TIPs reduces the amount of virus transmitted, and protects animals that came into contact with that treated animal," said Gladstone senior investigator Leor Weinberger.

The benefit of TIPs, though, goes beyond their ability to stifle a virus inside infected cells.

Since TIPs reside inside the same cells as the virus they target, they evolve at the same time, staying active even as new viral strains emerge.

"Over the last few years, many of the challenges of the pandemic have been related to the emergence of new variants," said Chaturvedi.

"TIPs would be an ideal treatment because they keep learning as the virus evolves, so they could keep the problem of drug resistance in check," she noted.