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  • The National Institutes of Health (NIH) have begun testing an experimental universal flu vaccine.
  • A universal vaccine would be more effective and not require yearly shots.
  • Scientists hope the vaccine can be delivered nasally, blocking infections and reducing transmission to other people.

“Influenza can be considered a ‘continuously emerging’ infectious disease, and the diverse and rapidly evolving influenza viruses are a significant public health threat,” Dr. Jeffery K. Taubenberger, senior investigator for the NIH, told Medical News Today.

“On a global level, millions of influenza infections occur annually, mainly in the form of seasonal epidemics causing millions of severe infections and up to 500,000 deaths.”

– Dr. Jeffrey K. Taubenberger

“On top of that,” he noted, “the unpredictable introduction of antigenically novel influenza A viruses from animals to humans can lead to the development of pandemics with even greater public health impacts. The 1918 influenza pandemic resulted in at least 50 million deaths globally.”

Dr. Taubenberger is the principal investigator of a promising animal study testing a universal flu vaccine in mice.

While the final publication of Dr. Taubenberger’s research is not expected until later this month, it has become the basis of a universal vaccine candidate called BPL-1357. It is now entering phase 1 clinical trials at the NIH to assess its safety for humans.

A successful universal flu vaccine would be effective against current and future viral strains and not require yearly reformulation or shots.

“If such a vaccine strategy could be developed,” said Dr. Taubenberger, “this would be a major public health achievement.”

BPL-1357 contains strains of avian flu. Dr. Taubenberger explained why: “All influenza A viruses in humans are ultimately derived from the wild avian viral pool, which is very extensive and diverse antigenically and genetically.”

“In birds, there are 16 subtypes of hemagglutinin (HA) and 9 subtypes of neuraminidase (NA), the two major surface proteins of the virus,” he pointed out.

“We chose a set containing 4 HA subtypes — H1, H3, H5, and H7 — for two reasons,” he went on to explain. “First, H1 and H3 have caused the majority of human influenza infections over the last century. H5 and H7 avian viruses have caused a number of zoonotic human infections, and are considered possible pandemic threats. Secondly, H1 and H5 are group 1 HA molecules, while H3 and H7 are group 2 HAs, [that] hopefully maximize development of broad protective immunity.”

Similar considerations went into the selection of NA strains.

All the strains in BPL-1357 are killed viruses.

While theoretically safe, Dr. Sylvie Alonso, associate professor at the National University of Singapore — not involved in the current research — cautioned, “manufacturing of this type of vaccine is a complicated process that has a certain level of safety risk since big quantities of live virus need to be grown and handled.”

Dr. Alonso added, that it “requires stringent safety checks to ensure that the inactivation of the viruses has been 100%. Ensuring that the virus does not mutate while being cultured in big quantity is also an important aspect.”

The NIH clinical trial will test the delivery of BPL-1357 both via intramuscular injection and intranasally. Researchers are hopeful that the nasal delivery route will be at least as successful as the shot.

Dr. Peter Palese, professor and chairman of the Department of Microbiology at the Icahn School of Medicine at Mt. Sinai in New York City — also not involved in the animal study or trial — told MNT:

“It is a very good strategy because the antibodies are right in the mucosal area, [so infection is less likely] and second, because they are also preventing transmission from [one] immunized person to the next one.”

In children, he said, a nasal vaccine can be a “very, very good vaccine. In adults the efficacy is somewhat lower, and there’s a very simple explanation. [Virally] naive children, if they get the vaccine, will make an antibody. [Many] older people have a partial pre-immunity that makes the live vaccine not as good in adults as one would hope.”

He remains hopeful for BPL-1357, though, since it uses killed viruses, “so that’s not a problem.”

Still, he is withholding judgment for now: “Okay, let me just say it is always easier to protect mice. So, I think this is a [like the] the Missouri license plate: ‘Show Me’.”

Dr. Palese explained the value of developing a universal flu vaccine: “We have always four components in our influenza vaccine. We have two influenza A components, and two influenza B components. Every year in February, there is an FDA [Food and Drug Administration committee] that has to make a decision based on surveillance what each of these four components will be in the next vaccine formulation.”

This decision is made in June or July, Dr. Palese says, in hopes that there will be a “good match of these components with the actual variants circulating in November or December.”

It does not always work, however. “We had even situations where we had really only 20% efficacy,” noted Dr. Palese.

Still, he pointed out that, even so: “The current influenza virus vaccines are, in my opinion, much better than their reputation is. Yes, they are not perfect. If they say it’s only 50% effective, in 50% of the cases, you have no symptoms whatsoever. In the other 50%, there are some symptoms. However, these are much milder than in a person who would not have been vaccinated.”

Dr. Palese says the yearly process is also very costly: “Every year a large number of doses of the influenza virus vaccines are actually thrown out because the next year, components have to be reevaluated.”

People also have to be reminded each year to get a flu shot.

“A universal vaccine,” said Dr. Palese, “could be defined as a vaccine that you don’t have to take every year, maybe only once in a lifetime.