Nasal spray for flu prevention shows promising trial results

Researchers have developed a nasal spray for flu prevention that has shown promising results in preliminary human trials. Seasonal influenza (the flu) is an acute respiratory infection that affects up to one billion people per year and causes hundreds of thousands of deaths. While flu shots can be effective, they are always a best guess because scientists are never fully certain about which strains will circulate. At best, they are only 50% effective, according to historical data.
Another way to try and tackle the flu is experimental monoclonal antibodies, which are proteins that mimic the immune system’s ability to fight off viruses, but these too have had limited success.
Spraying inside the nostrils
Scientists from Leyden Labs in the Netherlands and their partners have been working on a different approach: a spray you apply directly to the nostrils to block the virus at the point of entry. Their research is published in the journal Science Translational Medicine.
The spray contains an antibody called CR9114, which was developed by the pharmaceutical company Johnson & Johnson. Unlike conventional vaccines that can only recognize specific flu strains, CR9114 can recognize and block almost all types of influenza A and B.
Following successful tests in mice and macaques, in which the spray protected the animals against infection, the researchers conducted preliminary tests in 143 people aged 18 to 55.
Healthy volunteers were given either a single dose or a twice-daily dose for two weeks to test its safety and how it moves through the body (pharmacokinetics). The research team measured how long the antibody remained in the nose by collecting samples at different times. They also placed nasal samples in lab dishes with live flu viruses to see if CR9114 could neutralize the infection.
Optimal doses and next steps
No serious side effects were reported in any of the participants. Twice-daily doses were optimal because the nose naturally clears itself continually, and the antibody has a half-life of three hours. Even after being in the nose, the antibody was fully active and neutralized both influenza A and B.
One of the most impressive findings was that spraying the antibody directly into the nose resulted in antibody concentrations in the nasal lining up to 4,600 times higher than traditional IV methods and with smaller doses.
“Intranasal CR9114 is safe in humans and efficacious against influenza virus challenge in nonhuman primates. These studies pave the way toward intranasal antibody administration for broad, prophylactic protection against influenza virus infection and subsequent disease.”
While the research is promising, the scientists still need to confirm how well their spray works against natural infection and whether it stops the virus from spreading between people.