Hope for universal flu vaccine

Oregon Health & Science researchers say they have a promising new approach to developing a universal influenza vaccine — potentially within five years. 

Such a vaccine — a “one and done” dose — would provide a person with lifetime immunity against a rapidly evolving influenza virus and help safeguard against a pandemic like the recent one that also caused a respiratory illness. Flu strains have triggered six major epidemics in the past century and a half, with the worst in 1918 when millions of people died worldwide. 

Flu vaccines — and COVID shots — are based on targeting a particular strain that’s circulating. A universal flu shot would have to work against all strains of the virus, which mutates over time. So researchers adopted a new, OHSU-developed approach, according to the study, which was published this month in the journal Nature Communications. 

Researchers started by inoculating 11 monkeys with the 1918 flu virus. They then were exposed to an avian H5N1 influenza virus from 2005, a viral infection that originated with birds but is highly infectious for humans. Six of the 11 monkeys survived the exposure to H5N1. 

That’s a good outcome for the experiment considering the strength of the H5N1 virus, said senior author Jonah Sacha, professor and chief of the Division of Pathobiology at OHSU’s Oregon National Primate Research Center.

“We did that because we wanted to make it a really difficult test, so that if we saw any kind of signal, we could be confident that what we were seeing was real,” Sacha said in an interview. 

A control group of six primates did not receive the vaccine and also was exposed to the H5N1 virus. They all died.

Sacha said the method used to deliver the vaccine could potentially help other mutating viruses like SARS-CoV-2, the virus that causes COVID-19. 

“It’s a very viable approach,” he said. “For viruses of pandemic potential, it’s critical to have something like this. We set out to test influenza, but we don’t know what’s going to come next.”

Different approach

The key to the vaccine’s success was its method of delivery, called a platform. The one used in the flu vaccine trials was also developed by OHSU and is in clinical trials for HIV vaccines. 

The approach involves putting small amounts of the vaccine into a common herpes virus cytomegalovirus, or CMV, which infects people but usually produces no symptoms. Nevertheless, CMV prompts  an immune response which trains the immune system to fight the flu strains in the vaccine.

This is different from typical vaccines, including the existing flu vaccines, which rely upon an antibody response that targets the latest version of the virus.

By using an old version of the influenza virus, it was effective despite all the mutations of the past century.