PHOTO: ADAM DEAN120 8 APRIL 2022 • VOL 376 ISSUE 6589 science.org SCIENCEIN DEPTH
T
he two COVID-19 vaccines based on
messenger RNA (mRNA) have been
the breakout stars of the pandemic.
Both trigger impressive immune re-
sponses with minimal side effects,
and both did exceptionally well in ef-
ficacy trials. But the vaccines, produced by
the Pfizer-BioNTech partnership and Mod-
erna, have also split the world. Because
of their high prices and their need to be
stored at extremely low temperatures, few
people in lower and middle-income coun-
tries have had access to them.
That might soon change. More than a
dozen new mRNA vaccines from nine coun-
tries are now advancing in clinical studies,
including one from China that’s already in
a phase 3 trial. Some are easier to store,
and many would be cheaper. Showing they
work won’t be easy: The number of people
who don’t already have some immunity to
COVID-19 because of vaccination or infec-
tion is dwindling. But if one or more of the
candidates gets the green light, the mRNA
revolution could reach many more people.The Pfizer-BioNTech and Moderna shots
rely on mRNA to direct cells to produce
spike, a protein on SARS-CoV-2’s surface.
Although 23 COVID-19 vaccines are in use
around the world, based on technologies
including inactivated SARS-CoV-2 and cold
viruses engineered to carry the spike gene,
the two mRNA vaccines account for about
30% of the 13.2 billion doses produced so
far, according to health care data company
Airfinity. But the companies have been re-
luctant to share their intellectual property
(IP) and know-how, which would allow
manufacturers in poorer countries to pro-
duce the shots.
Instead, BioNTech and Moderna each re-
cently announced plans to build their own
plants in African countries. In a separate
effort, the World Health Organization has
created a training hub for mRNA vaccines
that will teach scientists from low- and
middle-income countries how to build and
run their own plants. But it may take years
before these efforts bear fruit.
The candidates already under develop-
ment could reach the marketplace much
faster. IP protections are still a challenge,says Melanie Saville, who heads vaccine
R&D at the Coalition for Epidemic Pre-
paredness Innovations: “Who can do what
and where is going to be a critical question.”
But the new mRNA developers have man-
aged to dodge some of the showstoppers.
Furthest along is a vaccine made by Wal-
vax Biotechnology in Kunming, China, to-
gether with Suzhou Abogen Biosciences and
the Chinese Academy of Military Science.
Details are hard to come by and Walvax
did not respond to detailed questions from
Science, but a paper about a phase 1 trial,
published in The Lancet Microbe in Janu-
ary, offers some information. Instead of
using mRNA that encodes the entire spike
protein, the Walvax team only included the
sequence of a key portion known as the re-
ceptor binding domain. In July 2021, the
company launched a placebo-controlled
phase 3 trial in 28,000 people in Mexico,
Indonesia, Nepal, and China.
A key advantage is that Walvax’s prod-
uct can be kept in a standard refrigerator,
says Víctor Bohórquez López, a clinician
who leads trials at five sites in Mexico for
Red OSMO, a network based in Oaxaca. ABy Jon CohenCOVID-New crop of mRNA vaccines aim for accessibility
If approved, they could bring the pandemic’s star vaccine technology to more of the world
A COVID-19 vaccine made by BioNet-Asia in Ayutthaya, Thailand, should be cheaper than the two messenger RNA vaccines used in richer countries.