13 February 2021 | New Scientist | 7ON 1 FEBRUARY, there was joy
in South Africa when 1 million
doses of the Oxford/AstraZeneca
coronavirus vaccine arrived. But
on 7 February, the health minister
announced that the vaccine’s
roll-out would be put on hold after
a small study suggested that it
doesn’t prevent mild or moderate
illnesses caused by the B.1.
variant responsible for almost
all covid-19 cases in the country.
The finding is worrying, not
least because the B.1.351 variant
is now spreading in several other
countries. The number of cases
detected outside South Africa
remains very low in most places
but Austria has found nearly 300,
leading the neighbouring German
state of Bavaria to threaten to close
the border. The UK has stepped up
testing to try to halt its spread.
It also seems past infection byother coronavirus variants doesn’t
protect against mild or moderate
infections by B.1.351, said Shabir
Madhi at South Africa’s University
of the Witwatersrand during a
video conference revealing the
findings. In a study of people given
a placebo in a trial of a vaccine
made by Novavax, the infection
rate was just as high in people who
tested positive for antibodies
as in those who had none.
That said, it is likely that the
Oxford/AstraZeneca vaccine
does still protect against
severe disease caused by the
B.1.351 variant, said Madhi.
South Africa might now roll out
vaccines to 100,000 people and
then check the hospitalisationrate, said Salim Abdool Karim,
who heads the country’s covid-
advisory committee.
Madhi pointed out that some
other vaccines have already
been shown to be effective
against B.1.351. “It’s not all
doom and gloom,” he said.
The Oxford/AstraZeneca
vaccine is effective against most
other variants, including the
fast-spreading B.1.1.7 variant first
detected in the UK. Results from
ongoing trials in the UK suggest
that the vaccine is 74 per cent
effective at preventing
symptomatic infections
due to B.1.1.7, and 85 per cent
effective for other variants.
A separate analysis of ongoingSouth Africa halts Oxford/AstraZeneca vaccine roll-out after evidence
it might not be effective against local variant. Michael Le Page reportsVaccine put on hold
News
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trials in the UK, Brazil and South
Africa concluded that a single
dose of the Oxford/AstraZeneca
vaccine is 76 per cent effective
at preventing symptomatic
infections between 22 and 90 days
after vaccination. A second dose
12 weeks or more after the first
boosts this to 84 per cent.
Unfortunately, results from one
small ongoing trial of the Oxford/AstraZeneca vaccine in South
Africa aren’t so good. The trial
began in June last year, and results
from the first months suggest
that the vaccine was about 75 per
cent effective at preventing mild
or moderate cases. There were no
severe cases. But once B.1.
became the dominant strain,
there was no significant difference
between outcomes in the vaccine
and placebo groups. It seems the
vaccine isn’t effective against
B.1.351, but because the numbers
are so low – just 1750 volunteers
and 42 symptomatic cases – there
are huge uncertainties.
The good news is that trials of
vaccines made by Novavax and
Johnson & Johnson show that
even though they are less effective
against B.1.351 than against other
variants, they are both still around
60 per cent effective at preventing
mild or moderate infections.
Crucially, the Johnson &
Johnson one-dose vaccine is 85 per
cent effective at preventing severe
or critical covid-19 in all countries
where it is being trialled, with
no decline due to B.1.351, said
Glenda Gray, also at the University
of the Witwatersrand.
The greater efficacy against
severe disease may be because
while B.1.351 evades antibodies
that prevent infection in the
first place, it cannot dodge
the immune system’s T-cells,
which help mop up infections. ❚People in South Africa
wait to receive the Oxford/
AstraZeneca vaccine“Some other vaccines are
effective against the South
African variant. It’s not
all doom and gloom”Daily coronavirus news round-up
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