Hepatitis A immunisation in persons not previously exposed to hepatitis A

Area of Science:

• Hepatology
• Immunology
• Vaccinology

Background:

• Hepatitis A virus (HAV) infection causes significant global morbidity and socio-economic loss.
• Hepatitis A vaccines (inactivated and live attenuated) offer potential prevention, but their efficacy and safety require clarification.

Purpose of the Study:

• To assess the clinical and sero-protective efficacy of hepatitis A vaccines.
• To evaluate the safety and harms associated with hepatitis A vaccination in previously unexposed individuals.

Main Methods:

• Systematic review and meta-analysis of randomized clinical trials.
• Searched multiple databases including Cochrane, MEDLINE, EMBASE, and CNKI up to November 2011.
• Extracted data on clinically apparent hepatitis A, sero-protection (anti-HAV IgG), and adverse events; assessed risk of bias.

Main Results:

• Nine randomized trials (732,380 participants) showed significant clinical protection against hepatitis A for both inactivated and live attenuated vaccines.
• Inactivated vaccines demonstrated effectiveness in preventing clinical hepatitis A (RR 0.09, 95% CI 0.03 to 0.30) and reducing lack of sero-protection (RR 0.01, 95% CI 0.00 to 0.03).
• Inactivated vaccines showed comparable safety to placebo; insufficient data existed for live attenuated vaccine safety.

Conclusions:

• Hepatitis A vaccines are effective for pre-exposure prophylaxis in susceptible individuals.
• Inactivated vaccines provide at least two years of protection, while live attenuated vaccines offer at least five years.
• Inactivated hepatitis A vaccines are safe; further high-quality evidence is needed for live attenuated vaccine safety.