LONDON- Britain will offer all 16 and 17 year olds their first dose of Pfizer COVID-19 vaccine, Britain's vaccine advisers said on Wednesday, extending eligibility of the shots to children beyond the clinically vulnerable.

Britain's Joint Committee on Vaccination and Immunisation (JCVI) said it was updating initial advice given last month in light changes in the spread of the disease in younger groups, and the latest safety data that was available.

"After carefully considering the latest data, we advise that healthy 16 to 17-year-olds are offered a first dose of Pfizer-BioNTech vaccine. Advice on when to offer the second vaccine dose will come later" said Wei Shen Lim, the JCVI's COVID-19 Chair.

"While COVID-19 is typically mild or asymptomatic in most young people, it can be very unpleasant for some and for this particular age group, we expect one dose of the vaccine to provide good protection against severe illness and hospitalisation."

JCVI said that the benefits to children of keeping them healthy and in school were paramount, though there would also be positive impacts on society more broadly.

Health Secretary Sajid Javid said he accepted the advice.

Britain has taken a much more cautious approach to vaccinating children than in the United States and Israel, which have pushed on with a broad roll-out for under 18s.

England's Chief Medical Officer Chris Whitty has stressed the need for a full picture on safety data of the shots, given extremely low rates of severe outcomes for the disease in that age group.

The JCVI said it was taking a precautionary approach on July 19 when it initially decided not to offer vaccines to children more broadly.

It maintained previous advice that children aged 12 to 15 with specific underlying health conditions should also get vaccines.

(Reporting by Alistair Smout; editing by Guy Faulconbridge) ((alistair.smout@thomsonreuters.com; +44 207 542 7064; Reuters Messaging: alistair.smout.thomsonreuters.com@reuters.net))