This statement acknowledges the growing body of evidence regarding the value of an additional booster dose for some population groups and highlights research gaps.

WHO with support of SAGE has reviewed the available data from seven studies published so far, which show some short-term benefit of an additional booster dose in the highest risk group (health workers, those over the age of 60 and immunocompromised persons). However, the data is only available for the mRNA vaccines and there is limited data regarding the duration of protection and the benefits of an additional booster dose for healthy younger people. More data is needed to evaluate the benefits of an additional booster dose for other population groups and vaccine platforms. When this is available, SAGE will update its recommendations accordingly.

Countries considering introducing a fourth additional booster dose should carefully weigh up the financial and programmatic challenges against the incremental benefits expected.

  • Background paper
  • booster dose
  • COVID-19