Hepatitis A vaccination and its immunological and epidemiological long-term effects – a review of the evidence

Abstract

Hepatitis A virus (HAV) infections continue to represent a significant disease burden causing approximately 200 million infections, 30 million symptomatic illnesses and 30,000 deaths each year. Effective and safe hepatitis A vaccines have been available since the early 1990s. Initially developed for individual prophylaxis, HAV vaccines are now increasingly used to control hepatitis A in endemic areas. The human enteral HAV is eradicable in principle, however, HAV eradication is currently not being pursued. Inactivated HAV vaccines are safe and, after two doses, elicit seroprotection in healthy children, adolescents, and young adults for an estimated 30-40 years, if not lifelong, with no need for a later second booster. The long-term effects of the single-dose live-attenuated HAV vaccines are less well documented but available data suggest they are safe and provide long-lasting immunity and protection. A universal mass vaccination strategy (UMV) based on two doses of inactivated vaccine is commonly implemented in endemic countries and eliminates clinical hepatitis A disease in toddlers within a few years. Consequently, older age groups also benefit due to the herd protection effects. Single-dose UMV programs have shown promising outcomes but need to be monitored for many more years in order to document an effective immune memory persistence. In non-endemic countries, prevention efforts need to focus on 'new' risk groups, such as men having sex with men, prisoners, the homeless, and families visiting friends and relatives in endemic countries. This narrative review presents the current evidence regarding the immunological and epidemiological long-term effects of the hepatitis A vaccination and finally discusses emerging issues and areas for research.

Viral hepatitis in 2021: The challenges remaining and how we should tackle them

“…In the United States, case-fatality estimates range from 0.3% to 0.6% for all age groups, rising to 1.8% amongst patients aged > 50 years[ 12 ]. A safe and effective inactivated vaccine has been in use for almost 30 years[ 13 ]. It was initially developed for individual prophylaxis, but now is used to control endemics[ 13 ].…”

“…A safe and effective inactivated vaccine has been in use for almost 30 years[ 13 ]. It was initially developed for individual prophylaxis, but now is used to control endemics[ 13 ]. A live attenuated vaccine has been developed and licensed in China and it is used in the Chinese national vaccination program.…”

“…Immunoglobulin was previously the only recommended PEP however due to a number of factors including declining anti-HAV IgG titres in donor pools, new strategies were sought. Recent data support post-exposure immunization with an inactivated HAV vaccine as being effective in preventing infection when given within 14 d of exposure[ 13 ].…”

Pharmacotherapeutic management of chronic viral hepatitis

“…Sometimes, if drugs are not used, liver damage can be life-threatening. [8]. There is no specific treatment, but only symptomatic based on the administration of vitamins and liver protectors.…”

“…Rigorous hygiene can reduce the risk of contamination, but does not provide effective and safe protection. Almost all patients with hepatitis A return to normal and gain immunity to this infection throughout their lives [8,9]. The covalescence period is 30-60 days, representing the period in which a periodic, clinical and laboratory control is made and healing is consolidated.…”