Flu vaccines take months to make. Here’s the thing that can speed it up

This story is part of CBC Health’s Second Opinion, a weekly analysis of health and medical science news emailed to subscribers on Saturday mornings. If you have not subscribed yet, you can do so click here,

For decades, the flu virus that’s in the vaccine you get each fall has been growing in chicken eggs.

Although it may seem strange, the tried-and-true technique has been around since the 1940s. Now, scientists are trying more innovative ways to develop vaccines.

Experts say it doesn’t count against the millions of chickens and their eggs that go into making influenza vaccines for the world each year, because the system works. But supplies may be short, and eggs can pose problems that researchers are making progress in solving.

Twice a year, the World Health Organization convenes an expert panel to decide what should be included in vaccines for the upcoming flu season in each hemisphere, based on the strains with the highest prevalence. It takes six months to decide which strains to include, purify the seed material, produce the shots on a large scale A in eggD. Get them in vials to go into the weapons.

These steps add to the lagging ability of vaccine manufacturers to adapt to the rapidly evolving vaccine virus, Meaning it cannot be last year’s vaccine Prevent stress this yearAnd the respiratory disease is highly contagious, causing fever, cough and body aches in most cases, but potentially causing serious complications such as pneumonia,

Virologists say another part of the problem is that many flu viruses originated in birds.

“You’re growing it in embryonated chicken eggs,” said Dr. Lenora Saxinger, an infectious disease specialist at the University of Alberta. In Edmonton. “And so it’s these bird cells that are growing the virus for you and the virus actually adapts to grow better in the bird cells.”

that cMatthew Miller, director of the DeGroot Institute for Infectious Disease Research at McMaster University in Hamilton, Ontario, said that sometimes viruses emerge that do not resemble the one that causes infection in humans, which could further reduce the effectiveness of influenza vaccines.

proof of concept vaccine

last week, New England Journal of Medicine Phase 3 clinical trial published pointing to potentially more effective option: mRNA flu shots.

Pfizer scientists did the test Made with a flu shot same mRNA technology used COVID-19 vaccines against traditional egg-based flu vaccine in more than 18,000 adults in the US, South Africa and the Philippines during 2022-23 flu season. They found that the mRNA version provided 34 percent greater efficacy. There was no placebo comparison.

“This is really a significant increase in improved protection over a season with strains that are circulating with this product,” Saxinger said. “This is an important proof of concept that is worth pursuing.”

Study revealed mild to moderate side effects like feverfeeling coldRedness was more common in those who received the mRNA influenza vaccine than the traditional jab.

“Feeling worse for up to 24 hours appears to be a feature of the current mRNA (vaccines),” Miller said. “I think there are ways that mRNA (vaccinia).ne technology) can develop into “Some of those systemic impacts will be mitigated in the future.”

Overall, for a single study, the take-home message is encouraging, said Angela Rasmussen, lead research scientist for the Vaccines and Infectious Diseases Organization at the University of Saskatchewan.

But disinformation about mRNA vaccines remains a problem. Rasmussen, admitted to Canada in 2021 from Columbia University in the US, is an active public communicator Of vaccine science.

“It’s really important that we meet people where they are; we address their concerns and their questions,” Rasmussen said.

“But we also really can’t afford for people to include things that are not true about these vaccine platforms as an argument to avoid developing them further.”

Weight measurement speed and cost

In traditional egg-based vaccines, the virus is grown in eggs and inactivated with a chemical. This way, only the virus particles without the virus can be detected by a person’s immune system. being able to repeat itself and The cause of infection, Rasmussen said.

In cell-based flu vaccinesIncluding one product available in Canada, the virus grows in dog kidney cells instead of chicken eggs.

This means avoiding the problems that come with the spread of the virus.n Bird’s eggs.

Another plus are cell vaccines can be manufactured fasterMiller said.

“In theory, (the World Health Organization), for example, could provide a later recommendation closer to flu season that avoids the possibility of mismatches.”

One disadvantage is that the cell-based vaccine is significantly more expensive, said Dr. Barry Pecks, an associate professor at the University of Toronto who treats respiratory infections, including influenza.

Pecks said that while the vaccines are simple to protect someone, their production is complex and resource-intensive. More Canadian manufacturing of vaccines could help secure supplies.

“Onshoring some of this — certainly with the political climate in the U.S. — is really important,” Pecks said.

Multi-weather protection?

Another non-egg-based influenza vaccine technology is a laboratory-made or recombinant version that is also faster to produce.

According to Miller, there is a variant available for influenza in Canada. It contains a purified part of the virus called hemagglutini.n, made in insect cells,

The option is helpful to look at the benefits and shortcomings of different vaccine platforms, he said.

“There are a number of new efforts being made to develop better mucosal vaccines, either administered as a nasal spray or administered by aerosol, which is what our group does,” Miller said.

McMaster vaccine is still in the pre-clinical stage of researchWhich means it has not been tested in humans.

“We are developing aerosolized influenza vaccines that we hope will provide better protection against both seasonal and pandemic viruses that is not only stronger but also has longer-lasting, multi-season protection.”

Pecks and Miller said that for the foreseeable future, Canada’s flu vaccine supply will remain primarily egg-based.

“Egg-based vaccines have worked well for a long time,” Miller said. “Comparative data shows … they do a very good job of preventing serious disease.”