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By Kate Kelland
LONDON, April 14 (Reuters) - A UK study into using different
COVID-19 vaccines in two-dose inoculations is being expanded to
include shots made by Moderna and Novavax,
researchers said on Wednesday.
The trial, known as the Com-Cov study, was first launched in
February to look at whether giving a first dose of one type of
COVID-19 shot, and a second dose of another, elicits an immune
response that is as good as using two doses of the same vaccine.
The idea, said Matthew Snape, the Oxford University
professor leading the trial, "is to explore whether the multiple
COVID-19 vaccines that are available can be used more flexibly".
Britain and many other countries in Europe are currently
using AstraZeneca's and Pfizer's COVID-19
vaccines in nationwide immunisation campaigns against the
coronavirus pandemic.
But reports of very rare blood clots have prompted some
governments - including France and Germany - to say the
AstraZeneca shot should only be given to certain age groups, or
that people who have had a first dose of AstraZeneca's vaccine
should switch to a different one for their second dose.
In a briefing about the expansion of the study to include
Moderna's and Novavax's COVID-19 vaccines, Snape, an associate
professor in paediatrics and vaccinology at Oxford, said it will
seek to recruit adults aged over 50 who have received their
first, or "prime" vaccination in the past 8-12 weeks.
These volunteers, who will have received either the
AstraZeneca or Pfizer vaccine, will be randomly allocated to get
either the same vaccine, or the Moderna or Novavax vaccine, for
a second dose.
The six new arms of the trial will each involve 175 people,
adding a further 1,050 recruits in total, Snape said.
"If we can show that these mixed schedules generate an
immune response that is as good as the standard schedules, and
without a significant increase in the vaccine reactions, this
will potentially allow more people to complete their COVID-19
immunisation course more rapidly," Snape said.
"This would also create resilience within the system in the
event of a shortfall in availability of any of the vaccines."
Results from the original mixing trial, using AstraZeneca
and Pfizer shots only, are expected as early as April or May,
while results of the second phase should come in July.
(Reporting by Kate Kelland. Editing by Mark Potter)
