The U.K. is laying the groundwork for a COVID-19 vaccine booster program starting in the fall, making it one of the first nations to do so.

The interim initiative would prioritize providing boosters to those 70 and older, other high-risk patients and frontline health workers starting in September.

Officials at the Joint Committee on Vaccination and Immunisation (JCVI) also are considering administering COVID-19 vaccines in tandem with flu vaccines. The organization doesn’t anticipate that variant-specific vaccines will be available in time for the launch of the new vaccination drive.

A second phase of the vaccine campaign would provide shots for those 50 and older, adults between the ages of 16 and 49 years who are in an at-risk group and adult household contacts of immunosuppressed individuals.

JCVI officials, however, haven’t made definitive plans yet and stated that the proposals regarding COVID-19 vaccine boosters are precautionary.

U.S. officials have discussed the possibility of supporting vaccine booster initiatives later this year but have stopped short of predicting they would be necessary.

U.K. has vaccinated more of its citizens than the U.S. Some 85% of U.K. adults have received at least one dose, and more than 60% are fully immunized. By contrast, 63.6% of the U.S. population aged 12 and up have received at least one dose. A total of 54.6% are fully vaccinated.

A handful of studies suggest that immunity from COVID-19 vaccines lasts at least six months. Immunity may last for a couple of years for healthy individuals.

As more data become available, the JCVI may update its proposals. “We will continue to review emerging scientific data over the next few months, including data relating to the duration of immunity from the current vaccines. Our final advice on booster vaccination may change substantially,” said Professor Wei Shen Lim, COVID-19 Chair for JCVI, in a statement.