What about Hepatitis A vaccine?

From the Guidelines

Hepatitis A vaccine should be administered to any person seeking protection from hepatitis A virus (HAV) infection, particularly those with high-risk indications, as it provides long-term protection against this serious liver infection. The vaccine is recommended for individuals such as men who have sex with men, persons who use injection or noninjection illicit drugs, persons working with HAV-infected primates or with HAV in a research laboratory setting, persons with chronic liver disease, and persons traveling to or working in countries with high or intermediate endemicity of hepatitis A 1. The first dose of the 2-dose hepatitis A vaccine series should be administered as soon as possible, ideally 2 or more weeks before the arrival of an international adoptee from a country with high or intermediate endemicity 1. Key populations that benefit from hepatitis A vaccination include:

• Men who have sex with men
• Persons who use injection or noninjection illicit drugs
• Persons working with HAV-infected primates or with HAV in a research laboratory setting
• Persons with chronic liver disease
• Persons traveling to or working in countries with high or intermediate endemicity of hepatitis A
• Unvaccinated persons who anticipate close personal contact with an international adoptee during the first 60 days after arrival in the United States from a country with high or intermediate endemicity. The vaccine can be administered in a 2-dose schedule at either 0 and 6 to 12 months (Havrix), or 0 and 6 to 18 months (Vaqta), or as a combined hepatitis A and hepatitis B vaccine (Twinrix) administered in 3 doses at 0,1, and 6 months 1. According to the most recent guidelines, hepatitis A vaccines induce protective antibody levels among virtually all adults, with 94%–100% of adults having protective antibody levels by 1 month after the first dose, and 100% achieving protective levels after a second dose 1. Kinetic models of antibody decrease among adults indicate that protective levels persist for >40 years, and seropositivity for hepatitis A persists for >20 years after completing 2-dose vaccination 1.

From the Research

Hepatitis A Vaccine Overview

• The Hepatitis A vaccine is often combined with the Hepatitis B vaccine to provide protection against both infections 2, 3, 4, 5, 6.
• The combined vaccine has been shown to be highly immunogenic and well-tolerated in various studies 3, 4, 5.

Immunogenicity and Safety

• The immune response elicited by the combined Hepatitis A and B vaccine is comparable to that of monovalent vaccines 2, 3, 5.
• The vaccine has been shown to provide rapid and sustained immune response against both Hepatitis A and B viruses when administered on an accelerated schedule 5, 6.
• The most frequently reported adverse events in clinical trials were injection-site pain and redness, and general fatigue and headache, with most events being mild and transient 3.

Vaccination Schedules

• Various vaccination schedules have been studied, including a two-dose schedule (0 and 6 months) and a three-dose schedule (0,1, and 6 months) 2, 3, 4.
• An accelerated schedule, administering three doses over three weeks and a fourth at 12 months, has been shown to provide rapid initial protection 5, 6.
• The choice of vaccination schedule may depend on the individual's risk of exposure and the need for rapid protection 6.

Benefits and Recommendations

• The combined Hepatitis A and B vaccine offers several advantages, including fewer injections, better compliance, and lower implementation costs 2, 3.
• The vaccine is recommended for individuals at risk of exposure, including travelers to endemic areas, individuals with high-risk behaviors, and certain occupational groups 2, 3, 6.
• A universal vaccination strategy may be considered to prevent the spread of Hepatitis A and B viruses 6.