The quality of evidence is downgraded by study limitations (unclear allocation concealment) and is upgraded by large magnitude of effect.
A Cochrane review [Abstract] 1 [withdrawn] included 9 RCTs with a total of 732 380 subjects to assess the clinical protective efficacy, sero-protective efficacy, and safety and harms of hepatitis A vaccination in persons not previously exposed to hepatitis A. Four trials assessed the inactivated hepatitis A vaccine (n=41 690) and 5 trials the live attenuated hepatitis A vaccine (n=690 690).
Compared to placebo, inactive control or no intervention, HAV vaccines demonstrated a significant protective effect against clinical hepatitis A, as illustrated below (Table 1). The effect was also similar when trials graded as having low risk of bias were compared to those with high risk of bias (RR 0.09; 95% CI 0.03 to 0.30 (3 trials) and RR 0.09; 95% CI 0.04 to 0.19 (6 trials), respectively).
| Studies /Subgroup | Number of participants (studies) | Relative effect(95% CI) |
|---|---|---|
| All vaccine types | 732 380 (9) | RR 0.09(0.05 to 0.17) |
| Inactivated HAV vaccines | 41 690(3) | RR 0.12(0.05 to 0.31) |
| Live attenuated HAV vaccines | 690 690(5) | RR 0.07(0.03 to 0.17) |
| High endemicity | 731 343(8) | RR 0.08(0.04 to 0.15) |
| Low endemicity | 1037(1) | RR 0.19(0.08 to 0.42) |
| Single dose regimen | 690 707(6) | RR 0.07(0.03 to 0.15) |
| Multiple dose regimen | 41 416(3) | RR 0.14(0.05 to 0.37) |
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