UPDATE 4-Britain lines up more potential COVID-19 vaccine supplies with J&J, Novavax deals

* Britain has now secured 6 types of vaccines

* Over 300 million doses secured to up chances of one that
works

* Britain also collaborating with J&J on two-dose phase III
trial
(Adds interview with UK vaccines chief)

By Alistair Smout and Josephine Mason

LONDON, Aug 14 (Reuters) - Britain will buy potential
COVID-19 vaccines from U.S. drugmakers Johnson & Johnson
and Novavax Inc, the companies said on Friday, boosting
the number of deals it has with drugmakers as the global vaccine
race rages on.

Britain and the United States are in the lead with six
vaccine deals with drugmakers each, as companies and governments
worldwide work overtime to find a vaccine against the pandemic
disease.

The latest agreements bring Britain's total number of doses
secured to 340 million, with options for millions more, for a
population of 66 million.

Britain said both vaccines could be available by the middle
of next year for priority groups, such as such as frontline
health and social care workers, ethnic minorities, adults with
serious diseases, and the elderly.

The deals cover a wide range of vaccine types currently in
development for COVID-19, as Britain seeks to hedge its bets
should one or more of the technologies prove ineffective.

"For now that is probably the bedrock of the portfolio. We
basically need to see now, what we want to add, if anything,
immediately that could diversify the sorts of vaccine that we've
got in the hopper now," Kate Bingham, chair of UK Vaccine
Taskforce, told Reuters.

"I think we're well placed... but I think we need to see the
data of some of these early vaccines first before we know what
is likely to be protective and what is not."

Johnson & Johnson said its Janssen Pharmaceutica unit will
supply Britain with its candidate, known as Ad26.COV2.S, with an
initial sale of 30 million doses on a not-for-profit basis for
emergency pandemic use.

The advance purchase agreement will also provide an option
for an additional purchase of up to a 22 million doses, it said.

Separately, Novavax said Britain would buy 60 million doses
of its vaccine candidate, NVX-CoV2373. Novavax will manufacture
some of the vaccine using Fujifilm Diosynth Biotechnologies
facilities in Stockton-on-Tees, northern England.

Alex Harris, head of global policy at the Wellcome Trust
health charity, said the deals put the Britain in a strong
position, and urged the government to explain how it will now
ensure fair and equitable access to vaccines for poorer
countries too.

"Without this...the risk increases that other rich countries
will seek to strike similar bilateral deals, potentially ...
leaving insufficient volumes of vaccine for the rest of the
world," Harris said in a statement.

The Janssen vaccine uses an adenovirus technique to ferry
coronavirus proteins into cells in the body, while the Novavax
shot uses a technology known as recombinant nanoparticle to
produce antigens - molecules that are designed to spur the
immune system into action.

Recent studies show the odds of an experimental vaccine
making it from early testing in people to regulatory approval
are roughly one in three.

J&J said it has also agreed to collaborate with the British
government on a global Phase III trial to explore the two-dose
regimen of its COVID-19 vaccine, which will run parallel to a
Phase III single-dose trials. Britain will also work with
Novavax on a late stage British-based trial.

No COVID-19 vaccine candidate has yet been proven effective
against the disease, but around 20 are in clinical trials.
(Reporting by Alistair Smout, Josephine Mason and Kate Kelland;
editing by Jason Neely, Ana Nicolaci da Costa and Louise
Heavens)