Nasal spray could prevent infections from any flu strain
Nasal sprays target flu viruses at their main point of entry into the body
Tatiana Maksimova/Getty Images
An antibody nasal spray has shown promise for protection against flu in preliminary human trials, after being first validated in mice and monkeys. It could be useful in combating future flu pandemics because it appears to neutralize any type of flu virus, including those spread from non-human animals.
The main tool we have to stop the spread of the flu is the annual vaccine, which stimulates our immune system to produce antibodies against recently circulating strains of the flu virus. However, because flu strains are constantly evolving, vaccines are only moderately effective.
To solve this problem, the pharmaceutical company Johnson & Johnson has developed a special antibody called CR9114, which can neutralize any of these strains. It does this by recognizing and binding to a part of the virus that always stays the same, regardless of how the other parts change.
When CR9114 was initially injected into the animals’ bloodstream, it failed to provide strong protection against the flu. In fact, only a small proportion reaches the nose, the main entry point for influenza viruses. In 2022, the company Leyden Labs licensed CR9114 and developed a formulation that could be sprayed into the nose.
Since then, the company has demonstrated that spraying CR9114 into the noses of mice and macaques prevents them from getting sick when exposed to various strains of influenza A and B, including one collected from a scientist’s throat during a bad flu season in 1933.
Preliminary tests were also carried out on 143 people aged 18 to 55. The researchers found that administering the spray twice daily maintained stable levels of antibodies in participants’ noses and caused no major side effects. Samples of their nasal mucus subsequently collected also neutralized a series of flu strains, including a strain of bird flu that entered humans in China in 2013.
The next step will be to directly expose people who have used the spray to a range of flu viruses to confirm that it actually prevents them from getting sick.
The spray may not be 100% effective because the virus can enter the body through routes other than the nose, such as the mouth, says Linda Wakim of the University of Melbourne, Australia. “But nevertheless, blocking the nasal entry would still intercept the virus at a major access point for infection.”
It will also likely be less convenient than the flu vaccine because it requires twice-daily administration rather than a single injection, Wakim says. “However, it could be a game-changer for specific high-risk groups, such as immunocompromised people, frontline healthcare workers or during a pandemic situation where rapid, short-term protection of the population is needed during vaccine development or deployment.” »
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