Britain offers all over-50s first COVID-19 shots in boost for PM Johnson
* Britain has offered shots to high-priority groups
* Johnson: aim to offer all adults a shot by end-July
* Moderna rollout begins in England
* Surge testing in London to track South Africa variant
LONDON, April 13 (Reuters) - Britain has offered all over-50s a first dose of COVID-19 vaccine as the rollout of Moderna's shot in England began on Tuesday, the government said, adding it was on track to give a shot to all adults by the end of July.
Britain has seen one of the world's quickest vaccine rollouts, behind only Israel in the proportion of its population receiving at least one dose of a COVID-19 shot.
The government said it had offered at least one shot to priority cohorts 1 to 9, which include all adults over 50, the clinically vulnerable, and health and social care workers, ahead of a target to do so by Thursday.
"We will now move forward with completing essential second doses and making progress towards our target of offering all adults a vaccine by the end of July," Prime Minister Boris Johnson said in a statement.
Britain has slowed down the pace of first doses, to ensure people in high-priority groups receive a second dose despite lower vaccine supplies in April than March.
In a boost to vaccine supplies for first doses, the rollout of Moderna's shot in England begins on Tuesday, after first doses were given in Wales last week.
Johnson's office said that the government remained on track to offer all adults a shot by July 31. People in their late 40s are expected to be the next to be invited for shots, his office said, pending confirmation from vaccine officials.
The success of the vaccine program has underpinned Johnson's roadmap out of lockdown, which on Monday saw all shops and outdoor hospitality settings in England reopen, with some celebrating on the street into the evening.
Adding a note of caution to the optimism, the government announced an expansion so-called surge testing in the south London boroughs of Lambeth and Wandsworth to detect cases of the variant first found in South Africa.
There have been 74 confirmed and probable cases of the coronavirus variant, known as B.1.351, in the boroughs, and there is concern that vaccines are less effective against it.
(Reporting by Alistair Smout; Editing by Nick Macfie)
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