By the time people test positive for COVID-19, the SARS-CoV-2 virus has already taken up residence in their respiratory system. With each breath, people expel invisible viral particles into the air – a process known as viral shedding.
Existing drugs aimed at treating COVID-19 relieve symptoms of the virus but do little to reduce viral shedding.
Researchers at the Gladstone Institutes in the US first developed a new approach to treating infectious diseases: a single-dose, intranasal treatment that protects against severe SARS-CoV-2 infection.
In a new study published in the journal Proceedings of the National Academy of Sciences, they show that this treatment, called a therapeutically interfering particle (TIP), also reduces the amount of virus released from infected animals and Limits transmission of the virus.
“Historically, it has been exceptionally challenging for antivirals and vaccines to limit transmission of respiratory viruses, including SARS-CoV-2,” said Gladstone investigator Lior Weinberger, senior author of the new research.
“This study shows that a single, intranasal dose of TIP reduces the amount of virus transmitted, and protects animals exposed to that treated animal,” Weinberger said.
The researchers noted that it is the only single-dose antiviral that not only reduces the symptoms and severity of COVID-19, but also sheds the virus.
Weinberger and Sonali Chaturvedi, a research investigator at Gladstone and the first author of the research, treated hamsters infected with SARS-CoV-2 with the antiviral TIP and then measured the amount of virus in the animals’ noses daily.
Compared to hamsters that did not receive TIP (called control animals), the treated animals had less virus in their nasal passages at each time point.
By day 5, all control animals were still shedding high levels of virus, while four of the five TIP-treated animals were undetectable, the researchers said.
“We know that the amount of virus shed is proportional to how infectious a person is,” Weinberger said.
“If viral shedding can be reduced, the number of secondary contacts likely to be infected will also be greatly reduced, which in turn will reduce the overall virus spread and help keep vulnerable individuals safe,” he said.
The researchers said that when SARS-CoV-2-infected animals were kept in cages with uninfected animals, treatment of infected animals with TIP could not completely prevent the transmission of COVID-19.
However, it significantly reduced viral load and mild symptoms of infection in newly exposed animals, he said.
“This particular laboratory setting is known to generate more efficient transmission than is generally seen in humans even in domestic settings, as hamsters transmit not only through aerosols, but also through bodily fluids and Climbing and grooming each other for several hours,” Weinberger said.
“Therefore, being able to reduce SARS-CoV-2 transmission in this animal setting is quite promising to be able to reduce human-to-human transmission,” he said.