Inhaled powder that coats airways can block coronavirus infection

A gel that lines the respiratory tract prevented coronavirus infections in mice and monkeys, and may also work against any future new variants


9 February 2023

SARS-CoV-2 could evolve into new variants that may evade existing vaccines

SARS-CoV-2 could evolve into new variants that may evade existing vaccines


An inhalable powder that coats the airways with a protective gel prevents coronavirus infections in mice and monkeys. It may be effective against any SARS-CoV-2 variant, including future ones that could evolve to evade existing vaccines.

Vaccines have been critical for containing the covid-19 pandemic, but their efficacy may wane as the coronavirus that causes it mutates. Ke Cheng at North Carolina State University and his colleagues wondered if they could create a barrier for the airways that temporarily blocks the virus from causing infections. This could protect people against new variants while new vaccines are developed or old ones updated.

First, they created a powder made of polymer and gelatin microparticles. When inhaled, this enters the mucus lining of the nasal passage and lungs, swelling to form a gel layer that blocks viral penetration.

When tested in mice, the powder’s particles remained at high levels in their lungs for 8 hours, blocking the virus from causing an infection with up to 75 per cent efficiency, with no safety concerns.

Next, it was administered to six African green monkeys via an inhaler device. Eight hours later, the monkeys were inoculated with the original SARS-CoV-2 strain or its delta variant, introduced into the animals’ noses or into their lungs via a tube.

Tests carried out several times over the next week revealed that the treated monkeys’ viral loads – the amount of virus in the body – were 50 to 300-fold lower than those of the animals in a control group that didn’t receive the gel before viral inoculation.

The gel coating didn’t seem to impair breathing or cause any other side effects.

The research team is seeking approval from the US Food and Drug Administration to test the gel in people. It could be inhaled using the same kind of device that people with asthma use when experiencing symptoms, says Cheng.

If approved, the inhaled powder may provide short-term protection for people entering crowded places, such as supermarkets or aircraft, says Cheng. “Even with an N95 mask, the virus can sometimes find its way in, so this could be an extra layer of protection,” he says.

In another part of the experiment, the team found the gel stopped mice from becoming infected with flu and pneumonia-causing viruses, suggesting that it could protect against a range of respiratory viruses with pandemic potential, says Cheng.

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