ba‐Andrade 2018.

Study characteristics
Methods	Matched case‐control study (from November 2013 to December 2015) carried out in São Paulo and Goiânia (southeast and Midwest regions, respectively, in Brazil)
Participants	Cases: defined as children aged 15 to 32 months with rash and either suspected as having varicella by an attending physician or being a contact to a confirmed varicella case. Cases were confirmed by either clinical or laboratory criteria. Controls: 2 neighbourhood controls were selected for each case.
Interventions	MMRV manufactured by GlaxoSmithKline. Evidence of prior vaccination was obtained from vaccination cards.
Outcomes	Cases were further classified by severity of disease based on number of skin lesions, being 1 of: mild – fewer than 50 lesions; mild/moderate – between 50 and 249 lesions; moderate – between 250 and 499 lesions; or severe – 500 lesions or more. Having been hospitalised or having any complication
Funding Source	Government
Notes	Conclusions: effectiveness of single‐dose varicella vaccine in Brazil is comparable to that in other countries where breakthrough varicella cases have also been found to have occurred. The goal of the varicella vaccination programme, along with disease burden and affordability, should be taken into consideration when considering the adoption of a second dose of varicella vaccine into national immunisation programmes.
Risk of bias
Bias	Authors' judgement	Support for judgement
CCS ‐ case selection	Low risk	Adequate ‐ laboratory‐confirmed
CCS ‐ control selection	Low risk	Adequate ‐ community control
CCS ‐ comparability	Low risk	Adequate ‐ for each case of varicella, 2 neighbourhood controls were selected, matched by age (15 to 32 months)
CCS ‐ exposures	Low risk	Adequate ‐ secure record ‐ vaccination cards
Summary Risk of Bias assessment	Low risk	Plausible bias is unlikely to have seriously altered the results.