Vaccine makers prep bird flu shot for humans 'just in case'; rich
nations lock in supplies
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 [March 20, 2023]
By Jennifer Rigby
LONDON (Reuters) - Some of the world's leading makers of flu vaccines
say they could make hundreds of millions of bird flu shots for humans
within months if a new strain of avian influenza ever jumps across the
species divide.
One current outbreak of avian flu known as H5N1 clade 2.3.4.4b has
killed record numbers of birds and infected mammals. Human cases,
however, remain very rare, and global health officials have said the
risk of transmission between humans is still low.
Executives at three vaccine manufacturers – GSK Plc Moderna Inc and CSL
Seqirus, owned by CSL Ltd - told Reuters they are already developing or
about to test sample human vaccines that better match the circulating
subtype, as a precautionary measure against a future pandemic.
Others, like Sanofi, said they "stand ready" to begin production if
needed, with existing H5N1 vaccine strains in stock.
There has also been a push among companies to develop a bird flu vaccine
for poultry, a market potentially far larger than that for humans.
Less reassuring, however, is that most of the potential human doses are
earmarked for wealthy countries in long-standing preparedness contracts,
global health experts and the companies said.
Many countries' pandemic plans say flu shots should go first to the most
vulnerable while supply is limited. But during COVID-19, many
vaccine-rich countries inoculated large proportions of their populations
before considering sharing doses.
"We could potentially have a much worse problem with vaccine hoarding
and vaccine nationalism in a flu outbreak than we saw with COVID,” said
Dr Richard Hatchett, chief executive of the Coalition for Epidemic
Preparedness Innovations (CEPI), which helps fund vaccine research.
An international framework for pandemic flu allocates 10% of global
supply for the World Health Organization to share with low- and
middle-income countries. By contrast, the WHO is seeking guarantees of
20% global supply for other types of pandemic in the wake of COVID.
The U.N. agency said it has signed legally binding agreements with 14
manufacturers for 10% of their pandemic flu vaccine “as it comes off the
production line", in a mix of donated doses and doses to be bought by
the agency at an affordable price. The agreements include six of the
largest seasonal flu manufacturers, such as GSK, Sanofi and CSL Seqirus,
the WHO said.
WHO did not comment on the potential for vaccine hoarding in a flu
pandemic but said mechanisms were being developed “so that countries can
work together – not in competition with each other” to respond to such a
crisis. It said it was “fully confident” manufacturers and member states
would meet their obligations.
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Ducks are seen inside a poultry farm in
Castelnau-Tursan, France, January 24, 2023. REUTERS/Stephane Mahe
 NEW APPROACHES
In a pandemic, vaccine manufacturers would shift production of
seasonal flu vaccines and instead make shots tailored to the new
outbreak when needed. They already have the capacity to make
hundreds of millions of doses.
Many of the potential pandemic shots are pre-approved by regulators,
based on data from human trials showing the vaccines are safe and
prompt an immune response, a process already used with seasonal flu
vaccines. This means they might not require further human trials,
even if they have to be tweaked to better match whichever strain
does jump to humans. Data on how well the vaccines actually protect
against infection would be gathered in real-time.
In all, the WHO said there are close to 20 licensed vaccines against
the broader H5 strain of flu. Existing antiviral treatments for
people already infected will also help mitigate the impact.
At the same time, moving to large-scale production of a more
targeted shot could take months, the manufacturers said. Some
potential shots use a traditional method, growing the virus used in
the vaccines in chicken eggs over four to six months.
“Creating the first dose is the easiest,” said Raja Rajaram, head of
global medical strategy at CSL Seqirus. “The hardest is
manufacturing in large quantities.”
Experts have long advocated for new approaches in developing
vaccines, both for seasonal and pandemic flu. COVID proved the
potential of mRNA technology to adapt more quickly to changing
viruses because the vaccines use genetic information from the
pathogen, rather than having to grow the virus itself.
Moderna’s mRNA vaccine research actually began 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 human trial of an mRNA pandemic
flu vaccine tailored to the new avian influenza subtype in the first
half of 2023, he said, adding Moderna could respond “very quickly”
in an outbreak scenario. The results will be closely watched, as the
data on Moderna’s seasonal flu candidate was mixed.
Nachbagauer said the company was mindful of the equity issue needing
to be addressed but has no contracts yet.
“It would be premature to sign anything or commit to anything that
we can’t actually deliver on as of today,” he said.
(Reporting by Jennifer Rigby; Additional reporting by Sybille de la
Hamaide; Editing by Hugh Lawson and Michele Gershberg)
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