It’s not necessarily obvious what part of the flu virus a potential mRNA vaccine should target. “You have to make sure you’re targeting the right part of the virus,” Scher says. In the case of Covid-19, the prominent spike protein fits the bill. However, flu viruses are likely more complicated and mutate more quickly, which means if you choose the wrong protein, the vaccine could be less effective than expected. The flip side, Scher suggests, is that mRNA vaccines could make it possible to target multiple proteins or parts of proteins from the same virus – a multi-pronged strategy.
And while they are arduous to develop, the speed at which mRNA vaccines can be produced could be extremely advantageous. Traditionally, flu vaccines contain inactivated viruses grown in chicken eggs. This works quite well, but these vaccinations take a long time to administer, which means health authorities must publish their forecasts well in advance of which strains of flu will circulate during the coming winter. If vaccines could be produced faster, more right predictions could be made closer to flu season.
Moreover, researchers hope that a single shot of mRNA could one day attack 20 or more strains of flu at once, eliminating the need for guesswork. Scher’s friends did they are working on such a “universal” flu vaccine.
As clinical trials are ongoing, this is still early days. Sheena Cruickshank, an immunologist at the University of Manchester, has been watching the news about emerging mRNA flu vaccinations with interest, but says questions remain. “We don’t know yet how long the immunity they produce lasts,” he says.
Michael Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota, agrees, although he notes that all flu vaccinations, regardless of how they are administered, have a waning immunity problem – protection may decline. by approximately 10 percent each month after injection.
A specific problem with mRNA vaccines is that they typically cost more than customary flu vaccines and must be refrigerated, which may make them arduous to roll out in areas with needy infrastructure. Scientists also fear they may face greater reluctance to get vaccinated. “The mRNA vaccine platform itself is probably the one that seems to garner the most misinformation,” notes Cruickshank. “That could be a flaw.”
The modern wave of mRNA flu vaccines may have a particular impact on older patients, says Jenna Bartley, an assistant professor at UConn Health, a health research center and hospital. Older people are at highest risk of getting the flu, but current vaccines are less effective in older age groups because their immune response is usually weaker. However, Covid-19 mRNA vaccinations have proven to be effective in older people as well as younger people.
It may be some time before mRNA vaccines for seasonal influenza are available. However, if the H5N1 virus begins to infect many more people, and especially if it turns out to be frequently transmitted between people, there is a chance that an mRNA vaccine for bird flu will be the first of its type to be implemented on a vast scale. US health officials said the H5N1 mRNA vaccine if needed, they can be made available within a few weeks.
Osterholm agrees that such a timeline is realistic. He notes that the real challenge would be to get any modern H5N1 vaccine to the people who need it most. He says Covid-19 vaccines have arrived in opulent countries and been delivered to people very quickly, but “for most of the world that hasn’t been the case at all.”