By Peter Loftus
The first vaccine that proves to safely protect people against
Covid-19 disease will be a breakthrough moment but is unlikely to
be the sole answer to curbing the coronavirus pandemic.
Instead, health experts say it's increasingly likely that
several vaccines could pass muster in clinical trials and become
available in phases over a period of weeks and months.
A multiplicity of experimental vaccines provides bench strength
in the event of more potential delays like the one AstraZeneca PLC
encountered earlier this week, after a volunteer in a U.K. vaccine
trial developed an unexplained illness, leading the company to
pause studies to review safety data.
Multiple vaccines would have implications for supply and
distribution plans. If testing is successful, it's possible that
rollouts of vaccine doses could start as soon as this coming fall
and stretch into 2021 and beyond.
"I think the general public maybe has the wrong impression that
there will be a winner and only one winner and everybody else will
be a loser, " Dr. Anthony Fauci, director of the National Institute
of Allergy and Infectious Diseases, said in an interview. "That's
not the case at all. I think it's quite conceivable, if not likely,
that you're going to have multiple candidates that'll get over the
finish line that will actually be good enough to be approved for
production and use."
Not all vaccines in testing are likely to succeed but several
have shown promise in small, early-stage human studies. At least
two vaccines are now in large, late-stage clinical trials in the
U.S., including one co-developed by Moderna Inc. with the National
Institutes of Health and another from Pfizer Inc. and BioNTech SE.
A third, from AstraZeneca and the University of Oxford, is on hold
pending the safety review.
The large trials are designed to generate enough evidence about
safety and efficacy to support a government decision on whether to
clear them for widespread use. Companies have said interim results
of the studies could be available starting in the fall, possibly as
soon as October, and if positive, could trigger U.S. authorization
of emergency use of the shots.
Novavax Inc. and Johnson & Johnson are planning to begin
large trials of their experimental vaccines this month, with
potential availability of initial doses by year-end or in early
2021. Vaccines developed in China and Russia also are in advanced
stages of testing and have shown promise in studies so far.
U.S. officials have signaled there could be at least two
vaccines available by the end of this year. The Centers for Disease
Control and Prevention sent documents last week to state officials
that lay out various scenarios, including availability of a limited
number of doses of two vaccines by the end of October with more
doses by the end of the year.
The CDC document doesn't name the two vaccines that could become
available but describes characteristics that match those of the
vaccines from Pfizer and Moderna.
Experts say multiple vaccines will be needed because no single
company can make enough for the whole world. Several companies have
signed contracts with the federal government to supply at least 100
million doses of each vaccine in the U.S., and are planning to
produce larger global supplies.
"We need multiple winners to have enough vaccines," said Dr.
Mark Mulligan, director of the NYU Langone Vaccine Center in New
York, which is helping to run a trial of the Covid-19 vaccine
co-developed by Pfizer and BioNTech.
Not everyone will be able to get vaccinated right away because
initial supplies will be limited -- perhaps 10 million to 15
million in the U.S., according to a draft report released this week
by the National Academy of Medicine.
There's likely to be a staggered rollout of which people can get
the shots. Last week, a National Academy of Medicine committee
proposed an allocation plan for the U.S. that would give the first
vaccine doses to front-line health-care workers in hospitals and
nursing homes who are at risk of infection.
These would be followed in phases by other groups such as older
adults in nursing homes, people with health conditions that
increase risk of more-severe Covid-19, and workers in essential
industries, before reaching the general population.
Having multiple vaccines could serve another purpose beyond
shoring up supply. Each vaccine may turn out to have different
safety and efficacy profiles, or other traits that could make it
more or less useful in certain groups, such as the elderly.
"There are going to be multiple vaccines of different degrees of
effectiveness, and different degrees of effectiveness in a range of
populations," said Dr. Peter Hotez, dean of the National School of
Tropical Medicine at Baylor College of Medicine and part of a group
trying to develop a low-cost Covid-19 vaccine for developing
countries. He says it's possible there will be four to five
successful vaccines within the next year.
Some vaccines could prevent coronavirus infections, which would
help reduce transmission of the virus, he said; others could reduce
the severity of Covid-19 disease but not prevent infections.
Any such differences would have to be borne out by the results
of the large Phase 3 trials, however, because the earlier studies
didn't test whether the vaccines prevented infections or reduced
Logistical traits could make one vaccine more suitable for
certain groups than others. For example, the two leading gene-based
vaccines, from Pfizer and Moderna, must be stored and shipped at
low temperatures, which could make them more suitable for
vaccinating health-care workers at hospitals or other facilities
that have the necessary storage equipment.
Having multiple vaccines could, however, add to the complexity
of waging a successful vaccination campaign.
Several vaccines require two doses, so providers would have to
track who gets which vaccine, and set up reminders to call them
back for the second dose. Health experts say there's no evidence
yet that two different vaccines could be given effectively to the
"It's going to add to the complexity on the ground, to those
people who are doing the vaccination," said Dr. Eric Toner, senior
scholar with the Johns Hopkins Center for Health Security. "I don't
think they can rely on patients to know which vaccine they received
or remember a month later."
Write to Peter Loftus at firstname.lastname@example.org
(END) Dow Jones Newswires
September 10, 2020 05:44 ET (09:44 GMT)
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