Volunteers who got two doses of the vaccine had high levels of
virus-killing antibodies that exceeded the average levels seen in
people who had recovered from COVID-19, the team reported in the New
England Journal of Medicine.
No study volunteers experienced a serious side effect, but more than
half reported mild or moderate reactions such as fatigue, headache,
chills, muscle aches or pain at the injection site. These were more
likely to occur after the second dose and in people who got the
highest dose.
Experts say a vaccine is needed to put an end to the coronavirus
pandemic that has sickened millions and caused nearly 575,000 deaths
worldwide.
Moderna was the first to start human testing of a vaccine for the
novel coronavirus on March 16, 66 days after the genetic sequence of
the virus was released.
Dr. Anthony Fauci, director of the National Institute of Allergy and
Infectious Diseases, whose researchers developed Moderna's vaccine
candidate, called the results "good news," noting that the study
found no serious adverse events and the vaccine produced "reasonably
high" levels of virus-killing or neutralizing antibodies.
"If your vaccine can induce a response comparable with natural
infection, that's a winner," Fauci said in a telephone interview.
"That's why we're very pleased by the results."
Moderna shares jumped more than 15% in after-hours trading on
Tuesday.
The U.S. government is supporting Moderna's vaccine with nearly half
a billion dollars and has chosen it as one of the first to enter
large-scale human trials. A successful vaccine could be a turning
point for Cambridge, Massachusetts-based Moderna, which has never
had a licensed product.
Moderna's shot, mRNA-1273, uses ribonucleic acid (RNA) - a chemical
messenger that contains instructions for making proteins. When
injected into people, the vaccine instructs cells to make proteins
that mimic the outer surface of the coronavirus, which the body
recognizes as a foreign invader, and mounts an immune response
against.
The results released Tuesday involved three doses of the vaccine,
tested in groups of 15 volunteers aged 18-55 who got two shots, 28
days apart. The groups tested 25, 100 or 250 micrograms of the
vaccine.
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Adverse events after the second dose occurred in seven of the 13 volunteers who
got the 25-microgram dose, all 15 participants who received the 100 microgram
dose and all 14 who got the 250 microgram dose. In the highest-dose group, three
patients had severe reactions such as fever, chills, headache or nausea. One of
these had a fever of 103.28 Fahrenheit (39.6 C).
"We didn't see any events that are characterized as serious adverse events,"
said lead author Dr Lisa Jackson of Kaiser Permanente Washington Health Research
Institute in Seattle, referring to reactions that require hospitalization or
result in death.
In June, Moderna said it selected the 100-microgram dose for its late-stage
study to minimize adverse reactions.
At that dose, Moderna said the company is on track to deliver about 500 million
doses per year, and possibly up to 1 billion doses per year, starting in 2021,
from the company's internal U.S. manufacturing site and strategic collaboration
with Swiss drugmaker Lonza <LONN.S>.
"It's a good first step," said Dr William Schaffner, a vaccine expert at
Vanderbilt University Medical Center who was not involved in the study.
"There's nothing here that would inhibit one from going ahead to the Phase
2/Phase 3 trials," he said.
In April, Moderna expanded the Phase 1 trial to include adults over 55, who are
more at risk of serious disease, with the aim of enrolling 120 volunteers.
Moderna said it will follow study volunteers for a year to look for side effects
and check how long immunity lasts.
Moderna started its phase 2 trial in May and expects to start a phase 3 trial on
July 27.
Phase 1 trials aim to ensure a treatment is safe and help determine an effective
dose. Phase 2 trials test a treatment in a larger group and get an early read on
effectiveness. Phase 3 trials are conducted in a large group of individuals to
confirm efficacy and identify rare side effects. Moderna's Phase 3 trial will be
conducted in 30,000 volunteers.
(Reporting by Julie Steenhuysen in Chicago; Editing by Matthew Lewis and Richard
Pullin)
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