13 February 2021 | New Scientist | 15the first phase of the immune
response and is vital to drive
adaptive immunity: antibodies
that learn to recognise the virus
and the white blood cells called
T-cells that destroy it.
CureVac uses mRNA built from
naturally occurring nucleotides,
stabilised in a different way.
This induces a strong innate
immune response as well as an
adaptive one, says Stefan Mueller
at CureVac.
The company is also developing
a portable mRNA printer, in
collaboration with Tesla, to rapidly
manufacture mRNA. These
printers could be taken to where
the vaccine is needed and used
to produce vaccines on demand.
CureVac’s vaccine is in phase III
trials. The UK says it will buy
50 million doses if it is approved.Vaxart: A vaccine pill
The campaign to vaccinate
everyone is a race against time,
especially as more dangerous
variants of the virus emerge.
According to Sean Tucker,
chief scientific officer of biotech
company Vaxart in San Francisco,
one rate-limiting step is getting
people to a vaccination centre
and injecting them. His solution
is to eliminate the needles.
Vaxart is at the early stages of
developing a covid-19 vaccine in
pill form that could be distributedby post. “The vaccine comes
to you,” says Tucker.
Vaxart’s pill contains a
weakened human adenovirus
called Ad5 loaded with genes from
the coronavirus – both the spike
protein and the nucleocapsid
protein, which forms the virus’s
shell – plus an adjuvant. The
tablets are designed to break
down in the small intestine,
stimulating an immune response.
Results of a phase I study
announced at the meeting show
that the pill elicits a response
from T-cells in the bloodstream
and antibodies in the lining of the
nose. However, it didn’t produce
antibodies in the bloodstream,
raising questions as to its potential
efficacy. This news caused the
company’s share price to crash.
However, Tucker points out that
the study met its stated goals and
says the company will press on.CanSino Biologics:
A child-friendly jab?
Getting news out of China’s
leading vaccine programmes,
run by the companies Sinovac
and Sinopharm, has proved
difficult. But one Chinese
company has revealed its hand.
CanSino Biologics, in Shanghai,
is developing a vaccine similar
to the Oxford/AstraZeneca one.
CEO Xuefeng Yu told the
conference that the vaccine is
in phase III trials. The vaccine
has already been administered
to more than 150,000 Chinese
military personnel with no
reported ill effects, although there
is no efficacy data because there
are so few cases in China, says Yu.
As part of a phase II trial in
Tiazhou, Jiangsu province,
30 children aged between 6 and
12 were given two shots. Yu says
the firm is now analysing safety
and immunology data.GCVI: Vaccinating the world
As the World Health Organization
warns, the pandemic won’t end
until the whole world is vaccinated.
Peter Hotez at Baylor College of
Medicine in Houston, Texas, and
his colleagues have now set up
the Global Coronavirus Vaccine
Initiative (GCVI) to get covid-
vaccines to the world’s poorest
people. They have a vaccine in
phase II trials in India, and it is
“about as straightforward and
simple a vaccine as you can
imagine”, says Hotez. It consists
of a vital bit of the spike protein,
grown in transgenic yeast and
mixed with an adjuvant.
This type of vaccine has a great
track record and is similar to a
common hepatitis B vaccine. Such
vaccines cost about $3 for two
doses. Experience suggests that
it will be suitable for children.
The GCVI will seek emergency
use authorisation in India within
months and is negotiating with
manufacturers in Africa, Latin
America and the Middle East. ❚PRE-TRIALS: Studies in the lab
PHASE 0: Studies in animal
models of the disease
PHASE I: A drug/vaccine is tested
in a small number of people to
evaluate safety and dosage
PHASE II: A drug/vaccine is
studied in a larger number of
people to assess how effective it
is and any further safety issues
PHASE III: A study in hundreds or
thousands of people to confirm
phase II results, assess side
effects and compare the drug to
already approved medications.
The drug is then submitted
for regulatory approval
PHASE IV: Monitoring of the
drug in the general populationTrial phases explained