For years, scientists have sought a universal flu vaccine — one that defends against all known types of the nasty virus — and recently there has been progress.

University of Pennsylvania scientists reported they used the same mRNA platform from the COVID-19 vaccines to develop a shot that produced antibodies in animals against 20 subtypes of influenza — far more than the two or four in the seasonal vaccine.

So what might people expect from such a vaccine in humans eventually, and in the meantime, as cases of the flu, plus RSV and COVID-19 swamp emergency departments and doctors’ offices? Here are some answers from Andrew Pekosz, a Johns Hopkins University flu researcher and professor in the department of molecular microbiology and immunology.

What is known about this flu season and the seasonal shot?

“The flu hit early and hard; normally we wouldn’t see these numbers until January,” Pekosz said.

Scientists are investigating if the circulating strains are particularly potent, as well as how well the vaccine matches. So far, he said, “The vaccine appears to be good, but the uptake appears no better than usual.”

The U.S. Centers for Disease Control and Prevention surveys show about a third of children and a quarter of adults were vaccinated as of October, a bit lower than normal for kids and higher for adults. No more than about half the population gets the flu vaccine during the season.

The Maryland Department of Health reports there are 211 people hospitalized for the flu, according to voluntary reporting from emergency rooms, and four adults have died this season. Doctors’ offices report thousands of visits for influenza-like illnesses.

Children are being hit particularly hard, with less immunity and less pandemic-era masking, Pekosz said.

“With Thanksgiving just past us,” he said, “I fear we’ll still see a lot more cases.”

What are the benefits of an mRNA vaccine?

“One of the big problems with the influenza vaccine is that it takes a long time to pick the strains and make the vaccine, which is grown in eggs, usually in the range of six months at minimum,” Pekosz said. “So if you want to immunize people in September, walking backward you need to make the decision in March.”

The mRNA vaccines can be produced more quickly, giving scientists time to see what strains are circulating before choosing them for the seasonal vaccine.

A universal mRNA vaccine might eventually eliminate the need to choose. And with broad protection, such a vaccine might also stop novel, pandemic-causing strains like the H1N1 strain in 2009, Pekosz said.

“A universal flu vaccine would be a sea change in the approach, but there is a lot more clinical work to show efficacy,” he said. “Companies are starting to line up human studies now.”

Why wouldn’t the vaccine boost antibodies, the warriors against infections, in humans like they did in animals?

Lab results are difficult to reproduce in humans in the real world, he said.

In the case of flu and COVID-19, people have had such a range of vaccinations and infections that they have different immunity levels and may respond differently. Antibodies also wane.

“Vaccines need to be tested on a lot of people over time to show what they can do,” he said.

What about making a flu-COVID-19 vaccine?

That could be coming, Pekosz said, but not this fall and maybe not next fall. Scientists haven’t even determined the optimal schedule for COVID-19 vaccinations, and many people have already gotten several.

“We can’t keep going with boosters every couple of months; that’s not a good long-term strategy,” he said. “If we give too many boosters too many times, the body will not mount a strong immune response.”

On the other side, uptake on shots has dropped each time they’ve been offered. About 90% of Marylanders of all ages have gotten at least one COVID-19 shot, but fewer than 17% have gotten the latest booster.

So, what do we do now about shots?

“It’s hard to come up with broad guidance because of the difference in immunity in the population,” Pekosz said.

That said, COVID-19 has not gone away. Hospitalizations are below January’s peak that exceeded 3,400. But there are currently 515 people hospitalized in Maryland with the virus — far more than those in hospital beds with flu or RSV. Though unlike the other respiratory illnesses, these severe COVID-19 cases are almost entirely in adults.

(There are 211 people hospitalized with flu and 88 hospitalized for RSV in the state. The RSV cases appeared to peak at 257 a few weeks ago. There is no RSV vaccine, though one is in the works.)

The newest bivalent COVID-19 booster includes the original version of the coronavirus and common strains of the omicron variant. The CDC recommends waiting at least two months between shots, though Pekosz recommended four to six months.

“The data is clear: The bivalent booster is producing a better response,” he said. “The question is how long the immunity will last.”

Pekosz hopes people will consider getting the booster and a flu shot, which state health officials call a “flooster” because they can be given at the same time. The illnesses can both cause an unpleasant week on the sofa even if they don’t lead to hospitalization.

And Pekosz added, “Even if you’re young and healthy and don’t feel like you’ll get that sick from flu or COVID, get vaccinated because cases have ripple effects. There are a lot of vulnerable people out there.”

meredith@thebaltimorebanner.com