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* Data behind UK booster decision published
* Pfizer and Moderna give large antibody, T-cell boosts
* Broad T-cell responses give hope of variant protection
By Alistair Smout
LONDON, Dec 2 (Reuters) - COVID-19 vaccines made by Pfizer
and Moderna that use mRNA technology provide
the biggest boost to antibody levels when given 10-12 weeks
after the second dose, a British study published on Thursday has
found.
The "COV-Boost" study was cited by British officials when
they announced that Pfizer and Moderna were preferred for use in
the country's booster campaign, but the data has only been made
publicly available now.
The study found that six out of the seven boosters examined
enhanced immunity after initial vaccination with
Pfizer-BioNTech's vaccine, while all seven increased
immunity when given after two doses of AstraZeneca's
vaccine.
"A third dose will be effective for many of the vaccines
we've tested and in many different combinations," Professor Saul
Faust, an immunologist at the University of Southampton and the
trial's lead, told reporters.
The study found that a full dose or half dose of Pfizer or a
full dose of Moderna gave a very effective boost to both
antibody and T-cell levels, regardless of whether the person
initially received Pfizer or AstraZeneca.
When AstraZeneca, Novavax, Johnson & Johnson and Curevac
were given as boosters, they increased antibody levels for
either initial vaccine, albeit to a smaller degree. However,
while Valneva boosted antibodies in people initially vaccinated
with AstraZeneca, it did not provide a boost for Pfizer.
The study found that booster shots also helped to generate a
broad T-cell response against the Beta and Delta variants, which
may play a key role in longer-term protection.
"T-cell (response) does seem to be broader against all the
variant strains, which gives us hope that a variant strain of
the virus might be able to be handled, certainly hospitalisation
and death, if not prevention of infection, by the current
vaccines," Faust said.
The study pre-dated the spread of the Omicron variant of
concern, but Faust said he had shared samples with the UK Health
Security Agency to generate data on Omicron as well.
(Reporting by Alistair Smout;
Editing by Bernadette Baum)
