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* Half-dose, full-dose could complicate vaccine
distribution-SII
* SII sees factors beyond efficacy as crucial in vaccine
decisions
* SII sees affordability, ease of storage and transport as
key
By Abhirup Roy and Euan Rocha
PUNE, Dec 1 (Reuters) - Serum Institute of India, which has
partnered with AstraZeneca to manufacture its COVID-19 vaccine,
will continue to test a two full dose regimen of the shot
despite it showing a lower success rate than a half and full
dose regimen in pivotal trials, a top executive told Reuters.
The British drugmaker has said its COVID-19 vaccine
could be up to 90% effective if administered as a half dose
followed by a full dose, but some scientists have questioned the
robustness of that result because only a few thousand people
were given that regimen in late-stage UK trials.
The global trials showed the efficacy rate of the shot was
62% if the full dose was given twice, as it was for most study
participants in trials in Britain and Brazil. AstraZeneca has
said it is likely to run an additional global trial to evaluate
the lower dose regimen.
SII which is currently running trials in India testing the
safety of AstraZeneca's vaccine as well as the immune response
it triggers, has no plans currently to alter them to include the
half dose-full dose regimen, according to Dr. Suresh Jadhav, an
executive director at SII.
"Anything which is beyond 50% is always going to be a plus,
plus," Jadhav said in an interview on Monday, referring to
efficacy rates. He added that changing the dose regimen now
would delay the trials.
A combination of two different measures could also
complicate rapid distribution efforts, according to Jadhav, who
has worked on vaccines for over four decades.
"When it is one common dose it becomes very easy. Whether it
is the first dose, or second it is the same vaccine, same dose,"
he said.
Over the weekend, SII said that it planned to apply for an
emergency use licence for the vaccine in India in the next two
weeks.
The 62% efficacy rate on AstraZeneca's broader two full dose
trial is above the 50% that U.S. regulators say is the minimum
required to consider a drug for emergency authorisation.
SII, based in the western city of Pune, is the world's top
manufacturer of vaccines by volume. Beyond AstraZeneca, it has
also partnered with other companies to potentially manufacture
their shots, including U.S. biotech firm Codagenix; its rival
Novavax and Austria's Themis.
But in the global race to develop vaccines to beat the
pandemic, AstraZeneca's vaccine is one of the frontrunners
despite having lower efficacy rates than some rivals.
U.S. drugmakers Pfizer and Moderna have
said their coronavirus vaccines have an efficacy rate of 95% and
94.5% respectively but AstraZeneca's drug is cheaper and easier
to transport because it can be stored for long periods at normal
fridge temperatures.
Those advantages are particularly important for many
developing countries and, therefore, for SII. As part of a deal
outlined in June, AstraZeneca has licensed SII to supply one
billion doses of its vaccine to dozens of low and middle-income
nations.
Most of the nations that are part of the COVAX initiative,
which has been set up to provide COVID-19 vaccines to poorer
countries, have indicated they would accept and use a proven
vaccine, if it showed more than 50% efficacy, according to
Jadhav.
Adar Poonawalla, the CEO of SII, said affordability,
scalability and ease of storage and transportation were key
factors for India and other emerging economies as they look to
decide on large scale purchases of vaccines.
"A vaccine that cannot penetrate and be given in a large
population to provide high vaccine coverage you may as well not
give it at all," Poonawalla told Reuters.
"If it's not affordable and logistically transferable, even
if it is 110% effective what is the sense?"
(Reporting by Abhirup Roy and Euan Rocha; editing by Carmel
Crimmins)
