The government has insisted the first supplies of the swine flu vaccine will be available by the end of August, despite speculation that its arrival in the country could be delayed.
Britain is expected to get around 60 million doses by the end of this year, which will be sufficient for half of the population. More vaccines will be available next year.
"The manufacturers have told us that they will be delivering the first supplies of the vaccine at the end of August," a spokeswoman for the Department of Health confirmed.
However, the vaccines - delivered by Baxter and GlaxoSmithKline (GSK) - could take a while to reach people as they have to be approved by the Joint Committee on Vaccination and Immunisation and the Medicines and Healthcare products Regulatory Agency before being put into use.
The spokeswoman said: "This is not the Department of Health's schedule - it is led by the manufacturers.
"We have contracts with manufacturers to supply enough vaccine for the whole population once it has been developed. These contracts were set up some time ago to ensure we are first in the queue."
The government has already prepared a priority list of people who will receive these vaccinations first.