Evidence for hepatitis a virus endemic circulation in Israel despite universal toddler vaccination since 1999 and low clinical incidence in all age groups

Background. Hepatitis A virus (HAV) molecular epidemiology in Israel was studied 1314 years after introduction of universal toddler vaccination (UTV), which reduced hepatitis A incidence from 50.4 to <1.0 per 100 000. Methods. An outbreak in Tel-Aviv with 75 cases in 20122013 was investigated. Real-time reverse-transcription polymerase chain reaction and sequencing of the VP1-2A region (1100 bp) was done on (1) acute hepatitis A patients' sera (n= 12/75 in Tel-Aviv and 31 patients hospitalized in 3 other major cities in 20112013) and (2) sewage samples (n = 27 from metropolitan Tel-Aviv, 14 from the other 3 cities, and 6 from Gaza). Results. The outbreak patients mean age was 33.2 years, 4 of 75 (5.3%) had been vaccinated, and 58 of 75 (77.3%) were hospitalized. Among sewage samples 16 of 27 (59.2%) from Tel-Aviv; 4 of 14 (28.6%) collected throughout Israel; and 6of 6 (100%) from Gaza contained HAV. Genotype IB predominated (n = 52/53 sequenced samples) and identical strains were demonstrated in the Israeli and Palestinian populations. Conclusions. Despite the UTV success, HAV circulation in the Israeli population is apparently facilitated by its close contacts with the endemic Palestinian population. Reassessment of vaccination policy is recommended.