Det er bedst, hvis den sidste dosis gives, inden barnet er 20 til 22 uger gammelt, og alle tre doser bør under alle omstændigheder gives, inden barnet er 26 uger (seks måneder) gammelt.
It is better if the last dose is given before the child is aged 20 to 22 weeks, and in any case, all three doses should have been given by the time the child is 26 weeks (six months) old.