UPDATE 3-Sanofi and GSK delay COVID-19 vaccine, marking setback to global fight

* Phase I/II results show low immune response in older
adults

* New study expected next year using improved antigen
formulation

* Eyes regulatory submission in the second half of 2021

By Matthias Blamont

PARIS, Dec 11 (Reuters) - Sanofi and
GlaxoSmithKline said clinical trials of their COVID-19
vaccine showed an insufficient immune response in older people,
delaying its launch to late next year and marking a setback in
the global fight against the pandemic.

The announcement on Friday, which highlighted the challenges
of developing shots at record speed, hinders efforts to develop
the multiple options that experts say the world needs to counter
a disease that has killed over 1.5 million people.

The news, which came on the same day as Australia axed a
domestic vaccine project, is also a blow for many governments
that have booked hundreds of millions of doses of the shot,
including the European Union, United States and Britain.

Shares in France's Sanofi were down 2.8% at 0910 GMT while
Britain's GSK was up 0.2%.

The two companies said they planned to start another study
next February, hoping to come up with a more effective vaccine
by the end of 2021.

The setback affects one of the most established technologies
in vaccines - used against the human papillomavirus, hepatitis B
and pertussis among other pathogens - which aims to introduce
lab-made proteins into the body to prod the immune system into
developing a targeted defence against the novel coronavirus.

It cements the lead of more novel approaches used by
vaccines from the likes of Pfizer-BioNTech and Moderna,
which use mRNA genetic technology to trick the body into
producing those proteins. Both of those shots were found to be
about 95% effective in successful large-scale trials.

Delays and additional trials are not unusual but the
Sanofi/GSK announcement highlights the unique set of challenges
facing drugmakers in multitasking science, speed and logistics
during a pandemic that has crushed global economies.

It also underscores why governments have spread their bets
by securing shots from different developers.

Australia cancelled the production of a COVID-19 vaccine
developed by the University of Queensland and using an adjuvant
made by biotech firm CSL after trials showed it could
interfere with HIV diagnosis.

DELAYED TO LATE 2021

Sanofi said Friday's results from Phase I/II trials showed
"an immune response comparable to patients who recovered from
COVID-19 in adults aged 18 to 49 years, but a low immune
response in older adults likely due to an insufficient
concentration of the antigen".

"With this type of vaccine, the result is not a surprise, we
know that more antigen is needed in older patients. But when in
Phase I and II, drugmakers test tolerance and one cannot test
strong dosages," said Jean-Daniel Lelievre, head of clinic
immunology and infectious diseases at Henri-Mondor hospital in
Creteil, France.

"I would think Sanofi and GSK will be able to improve their
vaccine."

Phase III studies were expected to start this month. However
Sanofi said it would instead launch a phase 2b study in
February.

"The study will include a proposed comparison with an
authorized COVID-19 vaccine," the company said, declining to
give further details on this.

"If data are positive, a global Phase III study could start
in Q2 2021. Positive results from this study would lead to
regulatory submissions in the second half of 2021, hence
delaying the vaccine's potential availability from mid-2021 to
Q4 2021."

The two companies said they had "updated governments and the
European Commission where a contractual commitment to purchase
the vaccine has been made."

BRITAIN JUMPS AHEAD

The vaccine uses the same recombinant protein-based
technology as one of Sanofi's seasonal influenza vaccines. It
will be coupled with an adjuvant, a substance that acts as a
booster to the vaccine, made by GSK.

Sanofi and GSK have scaled up manufacturing in order to be
ready to produce up to one billion doses of their vaccine in
2021. GSK said a goal to produce 1 billion doses of adjuvants -
with some expected to be delivered to other partners - in 2021
remained in place but was under review.

The Phase I/II study tested the safety, tolerability and
immune response of the vaccine in 440 healthy adults across 11
investigational sites in the United States..

This week, Britain started deploying the Pfizer-BioNTech
vaccine, jumping ahead of the rest of the world in the race.

Canada has also given the green light for the shot, while a
panel of outside advisers to the U.S. Food and Drug
Administration on Thursday voted to endorse emergency-use
authorization.

Rival developers AstraZeneca Plc and Moderna have
also reported late-stage data that shows their shots are
effective at preventing COVID-19.

Sanofi is also working on another vaccine candidate to
prevent COVID-19 with U.S. company Translate Bio which
will rely on a different technology called mRNA, similar to the
developed by Pfizer and Moderna. Phase I trials for this vaccine
are expected to start this month.

(Reporting by Matthias Blamont in Paris; Additional reporting
by Ludwig Burger in Frankfurt; Editing by Pravin Char)