Seroprevalence of hepatitis A and B viruses in medical school students planning for medical clerkships

Long-Term Effectiveness of Hepatitis B Vaccination in the Protection of Healthcare Students in Highly Developed Countries: A Systematic Review and Meta-Analysis

Hepatitis B virus represents an important global health problem. In highly developed countries, mass vaccination campaigns of newborns in recent decades have drastically reduced the proportion of carriers. However, workers exposed to blood and body fluids, including healthcare students, can be at risk of exposure. In order to assess the proportion of susceptible individuals in the specific population of healthcare students in highly developed countries, a systematic review and meta-analysis was performed to summarize the evidence on the persistence of humoral immune protection induced by the primary cycle of hepatitis B vaccination, as well as the proportion of true non-responders. Forty-six studies were included in the final analysis (52,749 participants). Overall, the seroprotection prevalence at the pre-exposure assessment was equal to 73.8% (95% CI 69.1-78.0); the prevalence of anamnestic response following the administration of a challenge dose was 90.9% (95% CI 87.7-93.3), demonstrating a high proportion of persistence of vaccination-induced immunity. Among those without evidence of anamnestic response, 5.0% (95% CI 2.1-11.5) were non-responders following the completion of a secondary immunization cycle. These findings demonstrate that the majority of healthcare students vaccinated with the complete HBV primary cycle maintain an effective humoral immunity against this pathogen for over two decades.

Changes in hepatitis A virus (HAV) seroprevalence in medical students in Bangkok, Thailand, from 1981 to 2016

Objective

This study aimed to determine the seroprevalence of anti-HAV IgG in Thai medical students in 2016 compared with the previous data and to demonstrate the cross-effective strategy to screen HAV seropositivity.

Results

Sera from 176 first-year medical students (age 19.07 ± 0.59 years; 50% female) at a university hospital in Thailand were tested for anti-HAV IgG. Data from HAV vaccination records and questionnaires were also collected. HAV seropositivity was unexpectedly high (62.5%, n = 110). 37.5% (n = 66) had an HAV vaccination record. Of these, 60.6% received the full HAV vaccination series, 4.5% received one HAV vaccination, 34.8% did not receive HAV vaccination, and 3.0% had natural HAV immunity. The long-term efficacy of HAV vaccination was at least 97.5% over a mean of 15.55 ± 2.44 years. There was a significant difference in immunity between students with (66.7%) and without (50.9%) vaccination records (P = 0.028). Most of the student’s parents had a bachelor’s degree or higher (87.9%; n = 272) and above average income (mean 17,000.76 ± 194.22 USD/person/year). Parental education and socioeconomic status influenced vaccination accessibility in these medical students. Screening of vaccination records instead of routine anti-HAV IgG testing is a cost-effective and reliable strategy to determine HAV immunity in medical students in Thailand.