There is currently no evidence available regarding the use of booster doses in children 5-11 years of age.
However, for older age groups, WHO recommends a booster (or third) dose 4 – 6 months after completing the primary series. WHO recommends that the booster vaccination of adults aged 60 years and above and persons with health conditions that put them at higher risk of severe COVID-19 outcomes, as well as medical workers and school staff, should be prioritized.
This is due to the increasing evidence of waning vaccine effectiveness against symptomatic disease (in people aged 12 and above), including – to a lesser extent – against hospitalization and severe disease over time. Vaccine effectiveness against Omicron and Delta can be restored in these age groups by a third dose.
It is not yet determined how long protection will last following a booster dose.