Hepatitis a virus infection in Central-West Tunisia: an age structured model of transmission and vaccination impact

• Published in: BMC infectious diseases Vol. 20; no. 1; pp. 627 - 13
• Main Authors: Ayouni, Kaouther, Naffeti, Bechir, Ben Aribi, Walid, Bettaieb, Jihène, Hammami, Walid, Ben Salah, Afif, Ammar, Hamadi, Ben Miled, Slimane, Triki, Henda
• Format: Journal Article
• Language: English
• Published: England BioMed Central Ltd 26.08.2020; BioMed Central; BMC
• Subjects: Adolescent; Adult; Age; Age Factors; Aged; Analysis; Antibodies; Asymptomatic; Child; Child, Preschool; Children; Demography; Disease transmission; Economic conditions; Epidemiology; Female; Food contamination & poisoning; Health aspects; Hepatitis; Hepatitis A; Hepatitis A - blood; Hepatitis A - epidemiology; Hepatitis A - prevention & control; Hepatitis A - transmission; Hepatitis A Antibodies - blood; Hepatitis A virus; Hepatitis A virus - immunology; Hepatovirus; Humans; Incidence; Infection; Infections; Infectious diseases; Laboratories; Male; Mathematical model; Mathematical models; Medical research; Middle Aged; Models, Theoretical; Morbidity; Mortality; Older people; Outbreaks; Parameter estimation; Prevalence; Public health; Seroepidemiologic Studies; Serology; Seroprevalence; Socioeconomic factors; Socioeconomics; Tunisia - epidemiology; Vaccination; Vaccination - methods; Vaccines; Viruses; Young Adult; Tunisia; Hepatitis A virus; Mathematical model; Vaccination; Public health; Seroprevalence
• ISSN: 1471-2334; 1471-2334
• DOI: 10.1186/s12879-020-05318-7

The epidemiological pattern of hepatitis A infection has shown dynamic changes in many parts of the world due to improved socio-economic conditions and the accumulation of seronegative subjects, which leads to possible outbreaks and increased morbidity rate. In Tunisia, the epidemiological status of hepatits A virus is currently unknown. However, over the past years higher numbers of symptomatic hepatitis A virus infection in school attendants and several outbreaks were reported to the Ministry of Health, especially from regions with the lowest socio-economic levels in the country. The aim of this study was to investigate the current seroprevalence of hepatitis A virus antibodies in central-west Tunisia and assess the impact of hepatitis A virus vaccination on hepatitis A epidemiology. Serum samples from 1379 individuals, aged 5-75 years, were screened for hepatitis A virus antibodies. Adjusted seroprevalence, incidence and force of infection parameters were estimated by a linear age structured SEIR (Susceptible-Exposed-Infectious-Recovered) compartmental model. A vaccine model was then constructed to assess the impact on hepatitis A virus epidemiology of 3 scenarios of vaccination strategies: one dose at 12-months of age, one dose at 6-years and one dose at 12-months and another at 6-years of age during 6 years. A rapid increase in anti-hepatitis A virus seroprevalence was noted during infancy and adolescence: 47% of subjects under 10-years-old are infected; the prevalence increases to 77% at 15-years and reaches 97% in subjects aged 30-years. The force of infection is highest between 10 and 30-years of age and the incidence declines with increasing age. The vaccine model showed that the 3-scenarios lead to a significant reduction of the fraction of susceptibles. The two doses scenario gives the best results. Single-dose vaccination at 6-years of age provides more rapid decrease of disease burden in school-aged children, as compared to single-dose vaccination at 12-months, but keeps with a non-negligible fraction of susceptibles among children < 6-years. Our study confirms the epidemiological switch from high to intermediate endemicity of hepatitis A virus in Tunisia and provides models that may help undertake best decisions in terms of vaccinations strategies.