Seven-year efficacy of RTS,S/AS01 malaria vaccine among young African children

RTS,S/AS01 is a malaria vaccine candidate that has undergone phase 3 evaluation across several sites in Africa that have varying intensities of malaria transmission. During more than 48 months of follow-up, immunization with the RTS,S/AS01 vaccine was estimated to be associated with rates of protection against clinical malaria of 36.3% (95% confidence interval [CI], 31.8 to 40.5) among children 5 to 17 months of age who had received a fourth dose and 28.3% (95% CI, 23.3 to 32.9) among those who had not received a fourth dose.1 The rates among young infants (6 to 12 weeks of age at the time of first vaccination) with more than 38 months of follow-up were 25.9% (95% CI, 19.9 to 31.5) among those who had received a fourth dose and 18.3% (95% CI, 11.7 to 24.4) among those who had not received a fourth dose.

The efficacy of vaccination with RTS,S/AS01 wanes over time.2 The potential for rebound in malaria cases (also referred to as “age shift”) as immunity wanes may lessen the public health usefulness of malaria vaccines. We present data from 7 years of follow-up to assess the possibility of a rebound.