25 July 2020 | New Scientist | 7AN EXPERIMENTAL coronavirus
vaccine developed at the
University of Oxford produces
the hoped for immune responses
in people. Even though it isn’t
yet clear if this means the vaccine
will prevent infections, the group
that made it has struck deals
for companies to make 2 billion
doses of it within a year.
“It’s a really important
day today,” says team leader
Sarah Gilbert. “But there’s
still a long way to go.”
At least 23 experimental
vaccines are being tested in
people. The aim of these trials is
to prove that the vaccines work,
but that will take time, because
it requires giving the vaccine or
a placebo to many thousands
of people in a region where there
are lots of coronavirus cases.
The latest findings were theresult of a smaller trial intended
to study the immune response
to find out if the vaccine is safe
and produces the intended effect.
About 1000 volunteers were given
the Oxford vaccine, which uses a
chimpanzee cold virus to deliver
the gene for the coronavirus
spike protein to human cells.
The modified virus can’t
replicate, so can’t cause infection
itself. No serious adverse effects
were reported in the study,
published this week (The Lancet,
doi.org/gg5gwk).
The volunteers did generate
lots of antibodies, proteins that
circulate in the blood and bind
to viruses. Not all antibodies bind
in a way that renders the virusharmless, but after one dose most
volunteers produced neutralising
antibodies, which do prevent
viruses infecting cells. After
two doses, all the volunteers
generated neutralising antibodies.
Their bodies also made immune
cells known as T-cells that seek out
and destroy infected cells before
they produce more viruses. This
cellular response is thought to be
an important part of immunity
to the coronavirus. “We are
super-excited by these results,”
says team member Teresa Lambe.
The antibody response
is comparable to that seen in
natural infections, but the cellular
response is stronger. However, it
remains to be seen whether thisAn early trial of a vaccine candidate from the University of Oxford has
produced a promising immune response, reports Michael Le PageVaccine immune boost
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newscientist.com/coronavirus-latestresponse is sufficient to protect
against infection and how long
this protection lasts.
Even if immunity fades fast
when people are infected with the
coronavirus itself, that doesn’t
necessarily mean vaccine-induced
immunity will do the same, says
team member Adrian Hill. “It’s
wrong to assume that,” he says.
It is also unclear how well the
vaccine will protect older people,who are at greater risk from
covid-19 and have a smaller
response to flu vaccines. The
Oxford trial involved only
people aged between 18 and 55.
In a paper published alongside
the Oxford one, a team in China
reported results from a trial in
which 603 volunteers were given
a dose of a similar vaccine,
called Ad5. It found that the
immune response was lower in
people aged over 55 (The Lancet,
doi.org/gg5gwj).
These studies aren’t the first of
their kind. US company Moderna
has found that its experimental
vaccine provoked protective
responses in 45 people. It has now
entered into larger, phase III trials.
The Oxford team is also
entering larger trials. About
8000 people in the UK have
already been given the vaccine,
and the trial is being extended to
include people over the age of 55.
Trials are also starting in the US,
Brazil and South Africa. Because
the number of covid-19 cases are
higher in these countries, these
trials may yield results sooner.
Pharmaceutical firm
AstraZeneca is already gearing up
to produce 1 billion doses of the
Oxford vaccine, and the Serum
Institute of India has also agreed
to make a billion. These will be
produced on a non-profit basis
while the pandemic lasts. ❚An early volunteer for
an Oxford vaccine trial
in Soweto, South Africa“After two vaccine doses,
all the volunteers produced
antibodies that prevent
viruses infecting cells”