Criteria used for assessing the risk of bias in included studies
| Criterion | None/minimal | Moderate | High |
| Eligibility criteria | Consecutive unselected population Selected from a general population Eligibility criteria explained | Selected from general population but criteria not clearly defined Eligibility criteria not clearly explained | Sample selection ambiguous Sample likely not representative Highly selected population |
| Methods for determining HSV-2 status | Methodology clearly defined and replicable Laboratory details including cut-off values reported HSV-2 seroconverters were properly accounted for | Methodology stated but details unclear | Methodology poorly defined or implemented and not replicable |
| Methods for ascertaining infant HIV status | Methodology clearly defined and replicable Laboratory details including cut-off values reported PCR-based testing or Ab-based testing at appropriate timepoints | Methodology stated but details unclear | Methodology poorly defined or implemented and not replicable |
| Methods to account for confounding | Controlled for, or excluded, patients with key confounders (eg, ARV, anti-HSV therapy, mode of delivery, feeding strategy) | Controlled for, or excluded, only certain confounders (eg, ARV, anti-HSV therapy, mode of delivery, feeding strategy) | Did not control for, or exclude, patients with key confounders (eg, ARV, anti-HSV therapy, mode of delivery, feeding strategy) |
| Analysis | Sample size calculation performed and achieved Analysis appropriate, no concerns | Sample size calculation unclear, but all available patients studied Sample size not achieved but explanation given Analysis appropriate by minor concerns | Sample size calculation unclear or not performed, or sample size not achieved Analysis has major concerns |
| Attrition | No/minimal attrition (<10%) Reasons for losses to follow-up explained | Moderate attrition (10%–20%) Reasons for LTFU incompletely explained | High attrition (>20%) Reasons for LTFU not explained |
| Overall | At least three items at low risk of bias No more than two items at moderate risk | At least three items at low to moderate risk of bias No more than item at high risk of bias | Not meeting criteria for low or moderate risk of bias |
HSV, herpes simplex virus.