Studies in adults

In 2 main studies, Prevenar 20 was shown to trigger immune responses that were comparable to those triggered by two other authorised pneumococcal vaccines (Prevenar 13, a vaccine that protects against 13 types of S. pneumoniae; Pneumovax 23, a vaccine that protects against 23 types of S. pneumoniae). Between them, Prevenar 13 and Pneumovax 23 cover the 20 types of S. pneumoniae (serotypes) targeted by Prevenar 20. Prevenar 20 was considered to be protective against pneumococcal disease based on the known effectiveness of Prevenar 13 and Pneumovax 23.

In one study conducted in around 3,000 people from 60 years of age, participants received either Prevenar 20, or Prevenar 13 followed one month later by Pneumovax 23. One month after each vaccination, the levels of antibodies across the 2 groups were comparable for all but one of the serotypes included in Prevenar 20. It was noted that although comparable, the antibody levels with Prevenar 20 were lower than with Prevenar 13 for most of the serotypes included in both vaccines.

This study also included around 900 people aged between 18 and 59 years who received either Prevenar 20 or Prevenar 13. In the Prevenar 20 group, the antibody levels against the 20 different serotypes were comparable to those seen in people aged 60 to 64 years who received Prevenar 20.

A second study tested Prevenar 20 in 875 participants who were at least 65 years of age and had all received a pneumococcal vaccine before (Prevenar 13 only, Pneumovax 23 only or Prevenar 13 followed by Pneumovax 23). In this study Prevenar 20 triggered immune responses against all serotypes and in all groups, but the immune responses differed considerably between the three different vaccine groups. Overall, the increase in antibodies after vaccination with Prevenar 20 was greater in people who had previously only received Prevenar 13 compared with those who had received Pneumovax 23 or Prevenar 13 followed by Pneumovax 23.

Studies in children

Two main studies looked at the immune response (as measured by the level of antibodies) triggered by Prevenar 20 compared with the response triggered by Prevenar 13 in a total of about 3,200 infants.

The results showed that Prevenar 20 triggered increased antibody levels against all 20 serotypes targeted by the vaccine; however, for some serotypes the antibody levels observed were lower with Prevenar 20 than with Prevenar 13.

When Prevenar 20 was given as a 4-dose regimen, the immune response was more similar to that seen with Prevenar 13 than when it was given as a 3-dose regimen. Therefore, only the 4-dose regimen has been approved for routine childhood immunisation.