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By Julie Steenhuysen and Kate Kelland
May 13 (Reuters) - COVID-19 vaccine developers are making
ever bolder assertions that the world will need yearly booster
shots, or new vaccines to tackle concerning coronavirus
variants, but some scientists question when, or whether, such
shots will be needed.
In interviews with Reuters, more than a dozen influential
infectious disease and vaccine development experts said there is
growing evidence that a first round of global vaccinations may
offer enduring protection against the coronavirus and its most
worrisome variants discovered to date.
Some of these scientists expressed concern that public
expectations around COVID-19 boosters are being set by
pharmaceutical executives rather than health specialists,
although many agreed that preparing for such a need as a
precaution was prudent.
They fear a push by wealthy nations for repeat vaccination
as early as this year will deepen the divide with poorer
countries that are struggling to buy vaccines and may take years
to inoculate their citizens even once.
"We don't see the data yet that would inform a decision
about whether or not booster doses are needed," said Kate
O'Brien, director of the Department of Immunization, Vaccines
and Biologicals at the World Health Organization (WHO).
O'Brien said the WHO is forming a panel of experts to assess
all variant and vaccine efficacy data and recommend changes to
vaccination programs as needed.
Pfizer Inc Chief Executive Albert Bourla has said
people will "likely" need a booster dose of the company's
vaccine every 12 months - similar to an annual flu shot – to
maintain high levels of immunity against the original SARS-CoV-2
virus and its variants.
"There is zero, and I mean zero, evidence to suggest that
that is the case," countered Dr. Tom Frieden, former director of
the U.S. Centers for Disease Control and Prevention.
"It's completely inappropriate to say that we're likely to
need an annual booster, because we have no idea what the
likelihood of that is," Frieden, who now leads the global public
health initiative Resolve to Save Lives, said of Pfizer's
assertions on boosters.
Pfizer, responding to the criticism, said it expects a need
for boosters while the virus is still circulating widely. That
could change once the pandemic is more firmly under control, a
company spokeswoman said.
Moderna Inc CEO Stephane Bancel aims to produce a
vaccine by the fall that targets a variant first identified in
South Africa and expects regular boosters will be needed.
The United States is preparing to have such doses on hand
for Americans, while the European Union, Britain and Israel have
ordered new supplies of COVID-19 vaccines to deploy as
protective boosters.
Some health experts, including Richard Hatchett, chief
executive of the Coalition for Epidemic Preparedness Innovations
(CEPI) that has funded many vaccine projects, say vaccine makers
are right to plan ahead for boosters given the uncertainty over
what will be needed in the long run.
Governments can then decide for themselves whether to buy
the products, he said.
"A LITTLE EVIDENCE"
Pfizer and German partner BioNTech SE have so far
found that their shot remains more than 91% effective for six
months after people received their second dose, compared with
nearly 95% demonstrated in their clinical trial. The companies
will track how robust the protection remains over time.
Dr. William Gruber, Pfizer's senior vice president of
vaccine clinical research and development, told Reuters earlier
this month the prediction for yearly boosters was based on "a
little evidence" of a decline in immunity over those six months.
Pfizer expects the COVID-19 vaccine to be a major revenue
contributor for years, and has forecast sales of $26 billion
from the shot in 2021. Global spending on COVID-19 vaccines and
booster shots could total $157 billion through 2025, according
to U.S. health data firm IQVIA Holdings.
Moderna President Stephen Hoge expects boosters will be
needed to keep immunity levels high, due in part to vaccine
hesitancy, as an estimated 30% of the U.S. population may not
agree to be vaccinated. As long as the virus is circulating
widely, people at high risk of severe illness may need to boost
their immune protection, Hoge said.
"All governments are in conversations with (Moderna) and
other companies about boosters," he said.
BROADER IMMUNITY?
Late last year, scientists were optimistic that highly
effective vaccines could quickly curb the global pandemic that
has battered economies and killed more than 3.4 million people.
Those hopes dimmed by February with evidence that mutant
versions of the virus might evade protection offered by
vaccines. Laboratory studies showed that the South African
variant could produce six to eight-fold reductions in antibody
levels among people vaccinated with the Pfizer or Moderna
vaccines.
Clinical trial data also showed that vaccines from
AstraZeneca Plc, Johnson & Johnson and Novavax
Inc were less effective at preventing infections in
South Africa, where the variant is widespread.
These studies spurred drug companies to start testing
booster doses of their vaccines and to develop shots that target
specific variants of the virus.
However, more recent research suggests that the Moderna and
Pfizer/BioNTech vaccines produce high levels of protective
antibodies to create a "cushion effect" against the known
variants, said Dr. Anthony Fauci, head of the National
Institutes of Allergy and Infectious Diseases (NIAID) and a top
White House adviser.
And antibodies - which block the coronavirus from attaching
to human cells - do not tell the whole story. Several studies
suggest that T cells - a type of white blood cell that can
target and destroy already infected cells - may help prevent
severe COVID-19 and hospitalization.
NIAID researchers found that T cells in the blood of people
who recovered from the original virus could still fight off
infections caused by the concerning variants found in the UK,
South Africa and Brazil.
"It's quite possible" that boosters would not be needed,
Fauci told Reuters. "It is conceivable that the variants will
not be as much a problem with a really good vaccine as we might
have anticipated."
Nevertheless, health authorities in the United States,
Britain and Europe are assuring their populations that a new
round of shots will be available if needed, with many nations
still desperate for vaccine supplies.
"It's a huge concern that ... wealthy countries would begin
administering booster doses and further constraining supply of
people's first dose of vaccine," said Rajeev Venkayya, head of
global vaccines for Takeda Pharmaceutical Co.
Dr. Monica Gandhi, an infectious disease doctor at the
University of California, San Francisco, said ultimately,
decisions on whether boosters will be needed "will best be made
by public health experts, rather than CEOs of a company who may
benefit financially."
(Reporting by Julie Steenhuysen in Chicago and Kate Kelland in
London; Additional reporting by Michael Erman in Maplewood,
N.J.; Editing by Michele Gershberg and Bill Berkrot)
