Fig. 2

Solicited local and systemic adverse events. Per protocol, adverse events were graded as mild/grade 1 (easily tolerated), moderate/grade 2 (interfering with daily activity), or severe/grade 3 (preventing daily activity), and in the case of fever as grade 1 (38.0–38.4 °C), grade 2 (38.5–38.9 °C) or grade 3 (≥ 39 °C). Post hoc, local adverse events were also graded according to the Food and Drug Administration (FDA) Adverse Event grading scale (Supplementary Fig. 2, Additional file 1), to more conservatively reflect observed local reactogenicity. If there was more than one episode per participant, the highest grade adverse event was listed. *One participant withdrew from follow-up after the first immunisation and adverse events for this participant were recorded only until 2 days after the first immunisation. The solicited systemic adverse event ‘rash’ was not reported during the study