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By Ludwig Burger
FRANKFURT, June 24 (Reuters) - Researchers at Oxford
University said on Thursday they have developed a method to
predict the efficacy of new COVID-19 vaccines based on a blood
test, potentially offering a short-cut around massive clinical
trials that are increasingly difficult to conduct.
The researchers looked at the concentration of a range of
virus-fighting antibodies in the blood of trial participants
after they had received the vaccine developed by AstraZeneca
and Oxford University, now known as Vaxzevria.
By looking at which of those trial volunteers later
contracted symptomatic COVID-19 and which did not, the
researchers came up with a model they hope will predict how
powerful other vaccines will be, based on those blood readings.
"The data can be used to extrapolate efficacy estimates for
new vaccines where large efficacy trials cannot be conducted,"
they said in their paper https://www.medrxiv.org/content/10.1101/2021.06.21.21258528v1.full.pdf,
which was posted online on Thursday and submitted for
peer-review for future publication in a scientific journal.
The Oxford researchers cautioned more work was needed to
validate their model for many of the highly contagious new virus
variants of concern.
They noted that they did not look into the so-called
cellular immune response, a major weapon of the human body
against infections alongside antibodies, but more difficult to
measure.
"There is an urgent need to increase supply of vaccines for
the world, but development and approval of new vaccines takes
many months. We hope that the use of correlates by developers
and regulators could speed up the process," said Andrew Pollard,
Director of the Oxford Vaccine Group and lead investigator on
the Oxford Vaccine Trial.
Researchers and regulators around the globe are working on
such benchmarks – known as a correlates of protection or
surrogate endpoints - which may allow laggards in the vaccine
development race to provide evidence of efficacy without having
to conduct trials with tens of thousands of volunteers.
Those mass trials have so far relied on participants to
contract the disease in their normal lives to provide vaccine
efficacy results. That becomes more of a challenge where
vaccination coverage is already high and the virus is not
circulating widely.
The traditional clinical trials also require many
participants to get a placebo as a comparison to those who
receive the experimental vaccine, posing an ethical dilemma
where approved shots are available.
(Reporting by Ludwig Burger
Editing by Bill Berkrot)
