UPDATE 2-S. Korean COVID-19 vaccine in late-stage test against AstraZeneca shot

* SK Bioscience candidate combines vaccine booster from GSK

* Results from study expected in first half of 2022

* SK Bioscience vaccine is S. Korea's first domestic shot
(Adds detail throughout)

By Pushkala Aripaka

Aug 31 (Reuters) - South Korea's SK Bioscience
and Britain's GSK said on Tuesday the drugmakers had
begun a late-stage trial of their COVID-19 vaccine candidate
against AstraZeneca's approved shot, the second study of
its kind globally.

The AstraZeneca vaccine will take the place of a dummy shot
in the trial, which will enrol about 4,000 candidates worldwide.
It will test SK's candidate, GBP510, in combination with GSK's
vaccine booster after positive early-stage data and a greenlight
from South Korea earlier this month.

Shots from Pfizer, Moderna, J&J and
AstraZeneca have been approved for use in South Korea. However,
its inoculation campaign has been dogged by vaccine shortages
and shipment delays https://www.reuters.com/world/asia-pacific/south-korea-opens-covid-19-vaccine-reservations-all-adults-2021-08-09
amid a surging fourth wave of infections.

A potential success of the SK vaccine, the country's first
domestic candidate, would help cut reliance on Western shots.

"While many countries have made good progress with
vaccination, there remains a need for accessible and affordable
COVID-19 vaccines to ensure equitable access and to protect
people across the world," said GSK Chief Global Health Officer,
Thomas Breuer.

The GSK-SK vaccine, if approved, would be supplied worldwide
through the World Health Organization-led COVAX vaccine sharing
programme, the companies said, adding that results from the
study were expected in the first half next year.

Researchers in some countries may not be able give a placebo
shot to people where an effective vaccine is widely available
for ethical reasons. France's Valneva is also
conducting a late-stage trial against AstraZeneca's shot.

The vaccine by SK, also a contract manufacturer for
AstraZeneca and Novavax, is a coronavirus protein-based
vaccine, while AstraZeneca's shot uses a modified version of a
common-cold virus to deliver immunity-building instructions.

British drugmaker GSK, the world's largest vaccine maker by
sales, has focused on supplying its adjuvant, or booster, to
developers rather than make its own shot in the first leg of the
vaccine race.

Shares of SK Bioscience closed up about 5% on Tuesday, while
GSK was down 0.6% in morning trade.

(Reporting by Pushkala Aripaka in Bengaluru; Editing by Shounak
Dasgupta and Edmund Blair)