Variable anti-HBs antibody titers in vaccinated birth cohorts – A cross-sectional population-based study

Abstract

BackgroundAfter the introduction of hepatitis B (HB) vaccination in 1995 in newborns, two catch-up campaigns targeted unvaccinated 9 year old in 2000–2003 (born 1991–1994) and the 18 year old in 2004–2008 (born 1986–1990), resulting in several birth-cohorts. Our objective was to assess the anti-HBs titers in each birth-cohort. MethodsWe included all outpatients (78.5%) and hospitalized patients with measured anti-HBs antibody titers in the Teaching Hospital of Infectious Diseases, Cluj-Napoca, Romania, during April 2014 – December 2018 (without HB history). We compared the anti-HBs titers in all birth-cohorts using the Lexis surfaces (titers by age, time period and cohort patterns). We also evaluated the number of acute HB in the corresponding inpatient birth-cohorts and special groups. ResultsWe included 2963 participants, mean age = 31.0 ± 14.2, 64.1% women. The birth-cohort 1995–2006, vaccinated after delivery (n = 424, 3-dose HB vaccine coverage > 90%), had significantly lower protective titers (41.3% >10 mIU/mL) compared to the other birth-cohorts: born after 2007 (also vaccinated at birth, 67.0%, n = 106), 1991–1994 (age 9, 74.3%, n = 847), 1986–1990 (age 18, 71.3%, n = 543). In the unvaccinated cohort (n = 1043, mean age = 45.5 ± 12.4) protective titers were found in 44.8%, probably after self-limited HB infection.Concordant results were found using the proportion of patients with detectable or robust titers, and median or geometric mean titers.Four breakthrough acute HB infections were hospitalized of the corresponding vaccinated cohorts (birth years 1988, 1990, 1995, 1996). Data on a few tested infants (n = 47, not included in the main study) demonstrated good protection, 88.9%. ConclusionsOur study demonstrated the long-term evidence of protection of HBV vaccine at two decades following the primary immunization and a booster seems unsupported. Further studies should be done to assess the need of a booster dose within the general population and special groups.