Date	Event	Description
31 January 2019	New search has been performed	In this 2019 update, we included 11 new trials (Beals 2016; Cunningham 2016; Hata 2016; Lal 2018; Levin 2018; Maréchal 2018; NCT00886613; NCT01505647; NCT02052596; Schwarz 2017; Vink 2017); excluded four new trials (Kovac 2018; MacIntyre 2010; Strezova 2017; Weinberg 2018); and identified five ongoing trials (NCT02180295; NCT02526745; NCT03116594; NCT03120364; NCT03439657). The 2019 update included a total of 24 trials that involved 88,531 participants.
31 January 2019	New citation required but conclusions have not changed	Our conclusions remain unchanged. Only one study evaluated the efficacy and safety of recombinant vaccine (Cunningham 2016). We pooled the results of this study with those of Lal 2015; there were no changes in the conclusions regarding the recombinant vaccine. The remaining 10 new included studies did not change our conclusions because most studies conducted isolated comparisons between different vaccine dosages, formulations, routes of administration, or interval schedules, Beals 2016; Lal 2018; NCT00886613; NCT01505647; Vink 2017, or conducted comparisons with other vaccines given in the other arm of the participant (Hata 2016; Levin 2018; Maréchal 2018; NCT02052596; Schwarz 2017).