By Thomas M. Burton
WASHINGTON -- U.S. government scientists are pushing back
against calls for one-dose regimens for two Covid-19 vaccines
designed to be administered with two shots, saying there isn't
enough evidence that a single dose provides long-term
"It is essential that these vaccines be used as authorized by
FDA in order to prevent Covid-19 and related hospitalizations and
death," Peter Marks, director of the Food and Drug Administration's
center that oversees vaccines, told The Wall Street Journal.
The FDA late last year approved a two-dose regimen for vaccines
from Moderna Inc. and from a partnership of Pfizer Inc. and
BioNTech SE. More recently it approved use of a one-dose regimen
for a vaccine from Johnson & Johnson.
Some scientists and lawmakers have called for shifting to a
one-dose regimen for all the vaccines, citing preliminary studies
showing one shot can be effective. They contend shifting to one
shot will allow the U.S. to accelerate the pace of
In a letter to Acting Health and Human Services Secretary Norris
Cochran March 2, seven physician members of Congress urged the
department "to consider issuing a revised emergency use
authorization as soon as possible" that might lead to single-dose
use of Pfizer and Moderna vaccines.
"Last week, the U.S. passed a sobering milestone of over 500,000
deaths related to COVID-19," said the letter, signed by lawmakers
including Rep. Andy Harris (R, MD.) and Rep. Gregory F. Murphy,
(R., NC). "These are staggering statistics, and anything we can do
to help prevent further tragedy -- to further protect the public
health and safety of the American people -- should be fully
In interviews, senior government scientists at the FDA and the
National Institutes of Health said such a shift isn't warranted,
saying the evidence used to approve the Pfizer and Moderna vaccines
was based on two doses.
These scientists said one dose may offer short-term protection,
but the longer-term protection is a question mark.
"You would be flying blind to just use one dose," said one
senior scientist and adviser to President Biden. "If you're going
to do something else other than follow the studies shown to the
FDA, show me that this one-shot effect is durable."
Another senior U.S. government doctor said the durability of the
vaccination is especially important when more-resistant strains of
Covid, including those from the U.K. and South Africa, are
appearing in the U.S.
"We think it's best to get people to as high a level of immunity
as possible," the doctor said.
The doctor added that the pace of vaccinations is accelerating
with the recent decision by Merck to help produce the J&J
"We're going to have a good supply of vaccines very soon," the
Representatives of Pfizer and Moderna didn't immediately respond
to requests for comment Saturday. Pfizer has previously said it
doesn't have data regarding the single-dose approach, and Moderna
has previously said it isn't studying the issue.
Paul A. Offit of the Children's Hospital of Philadelphia, who
served on the FDA advisory panel that recommended the use of the
Pfizer and Moderna vaccines, said those clinical trials "found a
level of neutralizing antibodies [with one dose] that was
significantly less than what they got with two doses."
The FDA advisory panel's chairman, Dr. Arnold Monto, also said
the two-shot regimen is best for the Pfizer and Moderna vaccines.
Dr. Monto, a public-health doctor at the University of Michigan,
stressed the need for two doses to counter the Covid variants.
"We've got information on a two-dose strategy," said Dr. Monto.
"We need high antibody levels from those doses to deal with the
Others holding fast with similar views in the U.S. government
are prominent infectious-disease doctor Anthony Fauci and Andy
Slavitt, a senior White House adviser for Covid response. Mr.
Slavitt said it would be a mistake for the U.S. government to be
persuaded by just one study.
University of Minnesota epidemiologist Michael Osterholm said in
testimony Thursday before the Minnesota legislature that the U.S.
should consider delaying second doses so more people can get first
"We could get more of our over-65 group vaccinated. I think the
data will support that actually is a very effective way to go."
Two weeks ago, researchers in Israel reported that one dose of
the Pfizer vaccine was 85% effective in preventing symptomatic
disease 15 to 28 days after inoculation.
In the U.K, the government has opted to stretch vaccine supplies
by delaying a second dose by up to 12 weeks in a bid to reach more
British researchers released preliminary data in recent days
saying that either of two vaccines -- from Pfizer and from
AstraZeneca PLC -- reduced the risk of hospitalization among people
older than 70 years old by 80%, compared to people of similar ages
AstraZeneca is still conducting a U.S. study of its vaccine,
which hasn't yet gained authorization from the FDA.
Write to Thomas M. Burton at firstname.lastname@example.org
(END) Dow Jones Newswires
March 06, 2021 17:03 ET (22:03 GMT)
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