Yes, they can continue working while waiting for the second dose.

The dose interval for the measles vaccine is at least 4 weeks. Personnel who have taken one dose should take the second dose 4 weeks after the first dose.

In the event that they fail to take a second dose, they will not fulfil the immunity requirement. Licensees should therefore ensure that personnel who have taken one dose take the next dose as soon as possible, once the minimum dose interval of 4 weeks has elapsed.