Imagine getting your flu vaccine as a pill, in the mail. Or imagine getting just one shot that would protect you against all of the different flu strains out there. Either way, it could mean an end to the yearly fall search for a fresh flu vaccine.
Neither advance is coming to a drugstore or clinic any time soon. But a series of new studies out this week shows solid progress toward a flu vaccine in a pill and a so-called universal flu vaccine that would protect against the virus even as it constantly mutates.
California-based Vaxart Inc. is working on pill-based vaccines and found one of their flu vaccine formulas seems to stimulate a good immune response in people.
Vaccines protect against illness by tricking the body into building up immune system proteins called antibodies that can act quickly if a certain virus or bacteria infects. Some vaccines work well when given orally — one of the polio vaccines is an example — but this is harder to pull off with flu.
"You can't just take a flu vaccine that is formulated for injection and turn it into an oral vaccine," Sean Tucker, founder and chief scientific officer of Vaxart, told NBC News.
"We had come up with a different way of getting the flu gene into the intestines and have the immune system recognize the flu gene as foreign."
It appears to have worked. In a very early Phase 1 safety study in 24 volunteers, nine out of 12 of the people who got the vaccine built up enough antibodies to be considered protected against flu, they report in the journal Nature Medicine.
"The kind of antibody that they are inducing with the vaccine is the type … that is strongly associated with protection in humans, so the findings are encouraging although they don't necessarily mean it will ultimately work," said Dr. John Treanor, a flu vaccine expert at the University of Rochester who is an unpaid adviser to Vaxart.
A lot more work is needed, Tucker said, but the findings are encouraging.
The pill that Tucker's team is working on would only be effective against specific strains of flu, just like the current shots and the nasal spray.
Flu mutates constantly and there are dozens of different strains, and hundreds of possibilities. In any one season three to four strains could be circulating and making people sick, which is why vaccines protect against three or four strains — H1N1, H3N2 and either one or two B strains.
It's also why people need a new flu vaccine every year.
Two teams of researchers are reporting on progress towards a so-called universal flu vaccine - that that could protect against a number of strains at once.
Flu vaccines train the body to recognize a specific part of the virus: a spike or mushroom-shaped structure called hemagglutinin. This is the structure that puts the "H" in flu strain names.
The "neck" of hemagglutinin is a little hidden and does not mutate the way more visible bits of the virus do. Researchers have been working on ways to help the immune system to see it. A vaccine targeting the neck or stem of the hemagglutinin structure might be more effective.
Dr. Gary Nabel, Dr. Barney Graham and colleagues at the National Institute of Allergy and Infectious Diseases have been working on this for years and they report in the journal Nature Medicine that they've designed one that protects animals against both H1 and H5 strains of influenza.
Theirs is based on a remodeled version of the H1N1 flu virus that started circulating in 2009. "It's a major reconstruction of the molecule," Nabel told NBC News.
It's easier said than done because cutting off the "head" of the hemagglutinin makes the whole structure unstable. But when they tested the vaccine they made in mice and in ferrets, which catch flu in much the same way as people do, it protected them against what should have been a lethal dose of H1N1 swine flu.
It's not yet even close to being a universal vaccine because H3 viruses have completely different structure, said Nabel, who now heads vaccine development at drug giant Sanofi. But, he added, "it's a step toward a universal vaccine."
"The technique is promising and a step in the right direction. It should be studied further and hopefully will be successful," said Dr. Walter Orenstein, associate director of the Emory Vaccine Center, Emory University School of Medicine.
Another team at the Scripps Research Institute and the Janssen Pharmaceutical Companies of Johnson & Johnson took a different route to making a hemagglutinin stem vaccine. "If the body can make an immune response against the hemagglutinin stem, it's difficult for the virus to escape," said Ian Wilson of Scripps, who worked on the study published in the journal Science.
Theirs protected mice against H1N1 and H5N1.
"While there is more work to be done, the ultimate goal, of course, would be to create a life-long vaccine," Wilson added.
And there's one more sobering study. It shows that protection against flu only lasts about 6 months after getting vaccinated. That's not because the virus is mutating, but because people's own immunity wears off. That's a completely different challenge facing researchers.