Effect of a hepatitis A vaccination campaign during a hepatitis A outbreak in Taiwan, 2015-2017: a modeling study
Abstract
BACKGROUND
Beginning from 2015-2016, unprecedented large outbreaks of acute hepatitis A predominantly affecting men who have sex with men (MSM) re-emerged across the continents. We assessed the impact of an early initiated hepatitis A virus (HAV) vaccination campaign that targeted HIV-positive MSM during the 2015-2017 acute hepatitis A outbreak in Taiwan.
METHODS
We first ascertained the effectiveness of HAV vaccination for HIV-positive MSM, who were disproportionately affected by the outbreak, using a nested case-control study of 1,470 HIV-positive persons who were initially HAV-seronegative. We then fitted a model of HAV transmission among MSM, risk-structured by HIV status, to the actual epidemic curve of reported acute hepatitis A cases in Taiwan during 2015-2017. Risk behaviors, serosorting, and effective population size were subjected to sensitivity analyses.
RESULTS
Fifty-five cases of acute hepatitis A were matched to 220 controls. Single-dose and two-dose HAV vaccination provided protection rates of 96.1% and 97.8% among recipient HIV-positive MSM, respectively. Model fitting yielded basic reproductive number estimates of 7.26 (HIV-positive MSM) and 3.04 (HIV-negative MSM). In a counterfactual scenario without an HAV vaccination campaign, the outbreak would involve 7,153 hepatitis A cases during 2015-2017 in contrast to the 1,352 actually observed cases. We therefore estimated that the HAV vaccination campaign averted 80.7% (sensitivity analysis: 48.8%-92.7%) of…
How strong is the evidence?
Evidence Hub reads this as a case-control, done in people. Its evidence level is 4 of 5 (Low · observational). Observational designs can show an association but not prove cause.
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