NEW YORK, June 24 (Reuters) - COVID-19 vaccines this fall
are likely to be based on the Omicron variant of the coronavirus
rather than the original strain, although some experts suggest
they may only offer significant benefits for older and
Moderna, Pfizer and Novavax have
been testing vaccines based on the first BA.1 Omicron variant
that became dominant last winter, driving a massive surge in
On Wednesday, Moderna said its updated vaccine worked well
against more recent Omicron subvariants, and that it was moving
forward with plans to ask regulators for approval.
Vaccines that can bridge the gap between the original
version of coronavirus and the Omicron variant would likely be
"far, far better" for the fall, according to Trevor Bedford, a
biologist at the University of Washington who has closely
tracked mutations of the SARS-coV-2 virus.
Bedford said it would take too long to meet regulatory
requirements for a switch to tailor the next vaccine to
versions of Omicron spreading quickly now.
"Catching up to any of the Omicrons is really important," he
said, noting the enormous jump in the number of mutations from
the original strain that emerged in China to Omicron on the
spike protein part of the virus the vaccines target.
The World Health Organization (WHO) plans to assess the
effectiveness of vaccines built for Omicron, as do national
health regulators like the U.S. Food and Drug Administration.
A group of WHO advisers said last week an Omicron-based
vaccine may broaden immunity after the Omicron variant evaded
much of the protection against infection generated by the
vaccines designed for the original virus, a view other experts
share. FDA scientific advisers will meet on June 28 to make a
recommendation on the issue.
Important questions remain, including whether vaccines
designed for variants circulating last winter will work well
against significantly different subvariants that may emerge.
Experts also want to know if the new shots will increase
protection against severe disease and death for younger,
healthier people or merely offer a few months additional
safeguard against mild infection.
Scientists who have questioned the value of booster shots
for young and healthy people say a broad campaign is not needed
with an updated shot either.
BILLIONS OF DOLLARS AT STAKE
Unlike annual adjustments for influenza vaccines that
manufacturers are allowed to try to align with circulating
strains, regulators have asked companies to run clinical trials
to prove their new COVID vaccines work better.
But nearly three years into the pandemic, vaccine makers are
pushing for a flu-like model that would allow them to nimbly
retool their shots to combat new variants.
At stake are billions of dollars in contracts with countries
around the world. Moderna is already manufacturing the shots,
with deals signed in some countries.
Moderna is asking regulators to greenlight a version of
their COVID-19 shot targeting both the BA.1 Omicron variant and
the original version of the virus, armed with fresh evidence it
may be effective against more recently circulating subvariants.
"The challenge we have is the virus continues to evolve
really quickly, Moderna President Stephen Hoge said in an
interview, noting that millions of doses of the updated vaccine
could be ready in August.
If the drugmaker needs to tweak the vaccine further and
restart manufacturing, new shots may not be available until the
middle of the fourth quarter, he said.
Pfizer and partner BioNTech are testing
variant-adapted COVID-19 vaccines but have yet to release any
data. Novavax, whose vaccine is not yet authorized for U.S. use,
launched a trial of its own Omicron-based vaccines in late May.
Dr. Jesse Goodman, a professor at Georgetown School of
Medicine and a former top FDA scientist, said unlike for flu,
regulators do not have enough experience with COVID vaccines to
match them to circulating strains without clinical trials.
Dr. Luciana Borio, former acting chief scientist of the FDA,
said the science generally supports the idea that it would be
better to have vaccines that more closely match the currently
"We see that with people that have hybrid immunity from
vaccination plus infection," Borio said. "The immune response
that is generated is very rich."
Still, Borio and others are not convinced everyone should be
"There's no evidence that a healthy 27-year-old person needs
to be revaccinated," Borio said.
(Reporting by Michael Erman
Editing by Caroline Humer and Bill Berkrot)