Vaccine makers like Moderna say they’re ‘standing ready’ for human bird flu pandemic

Major vaccine companies are preparing avian flu vaccines if the H5N1 virus that has killed millions of animals mutates to infect humans.

Vaccine makers GSK, Moderna, and CSL Seqirus have begun developing new human shots to target the rapidly spreading strain of the virus. Others such as Sanofi have vaccines for H5N1 virus in stock that could serve as a base for producing shots tailored to the currently circulating strain. 

Epidemiologists maintain that the risk to humans is low, but the specter of another pandemic upending hundreds of millions of lives worldwide has kicked scientific investigation into high gear.

The strain currently tearing through bird populations – H5N1 clade 2.3.4.4b – has not evolved to infect humans, but it has started spreading at an unprecedented rate in mammals after causing record deaths in birds – raising the prospect of the stain acquiring dangerous mutations.

It has already spilled into mammals like mink, foxes, raccoons and bears, sparking fears it may soon acquire worrying new mutations that would allow it to cause a human pandemic. The seals found in Maine are not reflected in this map

Like all flus, the virus is spread primarily through droplets in the air which are breathed in or get into a person’s mouth, eyes or nose

An 11-year-old Cambodian girl made headlines recently when she became the first human to die of bird flu this year.

But Cambodian scientists who sequenced the genomic makeup of the virus have confirmed that the clade that killed her – 2.3.2.1c – is not the one causing mass deaths in wild and domestic birds globally. 

Still, the virus’ proven ability to mutate quickly and jump from birds to mammals has begun to worry experts. There have been fewer than 1,000 cases in people, but it has killed roughly 53 percent of the people diagnosed with the disease.

World Health Organization Director-General Tedros Ghebreyesus warned last month: ‘Since H5N1 first emerged in 1996 we have only seen rare and non-sustained transmission of H5N1 to and between humans, but we cannot assume that will remain the case and we must prepare for any change in the status quo.’

The current avian flu outbreak has infected or killed more than 200million birds worldwide and thousands of mammals, including minks in Spain, seals in the US, sea lions in South America, and dolphins in the UK.

Executives at GSK, Moderna, and CSL Seqirus told Reuters that they are developing or are about to test sample human vaccines that better match the circulating subtype. Sanofi, meanwhile, said they ‘stand ready’ to begin production if needed, with existing H5N1 vaccine strains in stock.

The US also has a stockpile of chickens to produce eggs that are crucial to the development of flu vaccines, a method that has been in use for about 80 years.

Hundreds of thousands of eggs are transferred to locked and guarded facilities every day, their locations undisclosed as a matter of national security. 

To make the vaccine, a selected virus is injected into a hen’s eggs where it incubates and replicates for a few days in the same way it would in a human.

Scientists harvest liquid inside the egg that contains the virus and inactivate it so it can no longer cause disease, purify it, and leave behind the crucial antigen that prompts an immune response in the event of infection.

Moderna, meanwhile, manufacturer of one of two landmark mRNA vaccines for Covid, is working on a pandemic flu vaccine tailored to the avian flu using that same technology.

The basis of Moderna’s successful leverage of mRNA tech for Covid-19 was in seasonal flu shots. 

While vaccines would typically take years, even a decade, to develop, the Covid pandemic turbocharged the process, producing two highly effective mRNA vaccines in less than 12 months.  

Raffael Nachbagauer, Moderna’s executive director for infectious diseases, told Politico that the company is starting clinical studies for a pandemic avian influenza mRNA vaccine this year.

When they do, he hopes they could respond ‘within a two months time frame to a true pandemic outbreak’ with a shot equipped to fight the specific circulating strain.

There is a concern, though, that while many varieties of influenza vaccines have been pre-approved by regulators, mitigating the risk of lengthy human clinical trials slowing down the crucial distribution of shots, mass-producing versions that have been tweaked according to the specific strain could take months.

Raja Rajaram, head of global medical strategy at CSL Seqirus said: ‘Creating the first dose is the easiest… The hardest is manufacturing in large quantities.’