Vaccine makers prep bird flu shot for humans ‘just in case’ as rich nations lock in supplies

Some of the world’s leading flu vaccine makers say they could make hundreds of millions of bird flu shots for humans within months if the new strain of bird flu can cross the species divide.

One outbreak of avian flu known as H5N1, clade 2.3.4.4b, has killed a record number of infected birds and mammals. Human cases, however, remain rare, and global health officials say the risk of human-to-human transmission remains low.

Executives at three vaccine makers – GSK Plc Moderna Inc and CSL Seqirus, owned by CSL Ltd – told Reuters that they have developed or will test human vaccine samples that better match the circulating subtypes, as a preventive measure for future pandemics.

Others, like Sanofi, said they were “ready” to start production if necessary, with existing H5N1 vaccine strains.

Dr. Shayan Sharif, a professor at the University of Guelph, whose research focuses on the immune system of chickens, told CBC News that there is currently no vaccine licensed for use against avian flu in animals or humans in Canada, but that it is time to “think carefully” about how the vaccination campaign will be carried out. in this country.

“I hope we don’t need vaccinations for humans,” he said, “but I have to be prepared.”

There is also a push among companies to develop bird flu vaccines for poultry, a larger market than for humans.

The prescribed dose for rich countries

Most of the potential human doses are earmarked for rich countries in long-standing preparedness contracts, global health experts and the company said.

Many countries’ pandemic plans say flu shots should go first to the most vulnerable when supplies are limited. But during COVID-19, many vaccine-rich countries gave a large proportion of the population before considering sharing doses.

“We may have a worse problem with vaccine hoarding and vaccine nationalism during flu outbreaks than we saw with COVID,” said Dr. Richard Hatchett, executive chairman of the Coalition for Epidemic Preparedness Innovation (CEPI), which helps fund vaccine research. .

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The international framework for the flu pandemic provides 10 percent of global supplies to the World Health Organization (WHO) to share with low- and middle-income countries. In contrast, the WHO called for a guarantee of 20 percent of the global supply for other types of pandemics after COVID.

The UN agency said it had signed legal agreements with 14 manufacturers for 10 percent of the pandemic flu vaccine “due to exit the production line,” with a mix of donated and donated doses to be purchased by the agency at affordable prices. . The agreement includes the six biggest seasonal flu manufacturers, such as GSK, Sanofi and CSL Seqirus, the WHO said.

The WHO did not comment on the potential stockpiling of vaccines in a flu pandemic but said mechanisms were being developed to allow countries to work together, not compete with each other, to respond to the crisis. He said manufacturers and member states were “firmly confident” they would meet their obligations.

a new approach

In a pandemic, vaccine manufacturers will change production of the seasonal flu vaccine and make shots that match new outbreaks when needed. They already have the capacity to make hundreds of millions of doses.

Many potential pandemic shots have been approved by regulators, based on data from human trials showing the vaccine is safe and elicits an immune response, a process already used with seasonal flu vaccines. This means it may not require more human trials, although it may need to be modified to suit whatever strain makes the jump to humans. Data on how well the vaccine actually protects against infection will be collected in real time.

In total, the WHO says there are nearly 20 licensed vaccines against the broader H5 flu strain. Existing antiviral treatments for people who have been infected will also reduce the impact.

At the same time, moving to large-scale production of more targeted shots could take months, manufacturers say. Some potential shots use traditional methods, growing the virus used in the vaccine in chicken eggs for four to six months.

“Making the first dose is the easiest,” says Raja Rajaram, head of global medical strategy at CSL Seqirus. “The hardest part is manufacturing in large quantities.”

Experts have long advocated a new approach to developing vaccines, both for seasonal and pandemic flu. COVID proved the potential of mRNA technology to adapt more quickly to changing viruses because the vaccine uses the genetic information of the pathogen, instead of having to grow the virus itself.

Moderna’s mRNA vaccine research actually started with pandemic flu, and was modified for COVID, said Raffael Nachbagauer, executive director of infectious diseases at Moderna.

The company plans to launch a small trial of an mRNA pandemic flu vaccine that matches the new avian flu subtype in the first half of 2023, he said, adding that Moderna could respond “very quickly” in an outbreak scenario. The results will be closely watched, as data on Moderna’s seasonal flu candidate is mixed.

Nachbagauer said the company is considering equity issues to address but does not yet have a contract.

“It’s really not the time to go into anything or do anything that we can’t do right now,” he said.