* European Medicines Agency says two doses preferable
* Clinical data on single-dose efficacy still limited (Adds details, background)
LONDON, Oct 23 (Reuters) - Europe's drugs watchdog said on Friday that giving two doses of swine flu vaccine was preferable, even though many governments are pushing ahead with single-shot immunisation for most people.
One dose of GlaxoSmithKline's Pandemrix and Novartis's Focetria may be sufficient in adults, but the data so far is not conclusive, the European Medicines Agency said.
After reviewing the latest findings, the agency's Committee for Medicinal Products for Human Use (CHMP) said it continued to recommend that H1N1 vaccines be preferably used as two doses, at least three weeks apart.
"The CHMP noted that the data supplied to date are still limited and do not allow the committee to recommend the general use of a single-dose vaccination schedule," the London-based agency said in a statement.
The European Medicines Agency has so far approved three H1N1 vaccines -- Pandemrix, Focetria and Baxter International's Celvapan -- and others may be added later.
Initially experts thought two doses of vaccine would be needed for everybody because of the current H1N1 swine flu virus is a new strain. But in the past couple of months various clinical trials have suggested one dose may suffice.
As a result, many governments are now planning to give adults a single shot -- thereby stretching supplies and cutting costs.
In Britain, for example, where Pandemrix and Celvapan have been ordered, all those over 10 years of age receiving Glaxo's vaccine will get a single shot, but children will have two doses, as will everybody on Celvapan.
For a FACTBOX on vaccination plans across Europe, please click on: (Reporting by Ben Hirschler; Editing by Rupert Winchester)