Long-term protective effect of post-exposure Havrix administration during viral hepatitis Type A outbreaks

Hepatitis A vaccination

Hepatitis A is an important public health issue worldwide. Hepatitis A vaccine (HepA) was first licensed in 1992. Both inactivated HepA (HepA-I) and live attenuated HepA (HepA-L) are highly immunogenic and well tolerated, and immune protection postvaccination can persist for at least 20 y. HepA is effective for both preexposure and postexposure prophylaxis, especially among children and young adults. The strategy of HepA vaccination varies in different countries and mainly includes vaccination among high-risk populations, regional childhood vaccination and universal childhood vaccination. The incidence of hepatitis A has decreased greatly in many countries in the last 30 y, but hepatitis A outbreaks frequently occur among high-risk populations and those who have not been covered by universal child vaccination programs in recent years. Disease surveillance and serosurveys are suggested to clarify the shift in the epidemiology of hepatitis A. The long-term persistence of immune protection after one dose of HepA should be further studied, as well as the cost-effective evaluation of different strategies of HepA vaccination. Based on this evidence, the recommendation on HepA vaccination should be put forward scientifically and updated in a timely and well-implemented manner.

Investigating a community wide outbreak of hepatitis A in Kerala, India

Background:

There was an outbreak of acute hepatitis in Nellikuzhy panchayat of Kothamangalam taluk, Ernakulam district, Kerala, during November and early December 2016. Objective of this study is to describe the epidemiological features of the outbreak and to identify the probable source.

Materials and Methods:

The outbreak was defined in terms of time, place, and person. A hypothesis was generated and tested using a case–control study. Cases were selected by simple random sampling from the line list and controls were age-matched neighborhood individuals without any history of jaundice. Chi-square test, univariate analysis, and multi-variate logistic regression analyses were done to identify the probable risk factors.

Results:

Around 223 hepatitis A cases were identified. Attack rate was found to be highest among the age group of 16-30 years at 1.44% and was eight times higher among males. Epidemic curve suggested a point source outbreak possibly from exposure to food or water from a newly opened hotel in the area. The case–control study confirmed the hypothesis with a statistically significant association between cases and history of exposure to food from the hotel [OR 120; 95% CI 14.6–996.2; P value < 0.001].

Conclusion:

Observations and results of the case–control study revealed that the probable source of the Hepatitis A outbreak at Nellikuzhy panchayat was a hotel. The study findings also add evidences to the changing epidemiological pattern of hepatitis A in Kerala, and warrant the necessity to enforce food safety rules in the State.

Effectiveness of hepatitis A vaccination as post-exposure prophylaxis

Hepatitis A (HA) has been a vaccine-preventable disease since 1995. In Catalonia, a universal combined hepatitis A+B vaccination program of preadolescents was initiated at the end of 1998. However, outbreaks are reported each year and post-exposure prophylaxis (PEP) with hepatitis A virus (HAV) vaccine or immunoglobulin (IG) is recommended to avoid cases. The aim of this study was to assess the effectiveness of HAV vaccine and IG in preventing hepatitis A cases in susceptible exposed people. A retrospective cohort study of contacts of HA cases involved in outbreaks reported in Catalonia between January 2006 and December 2012 was made. The rate ratios and 95% confidence intervals (CI) of HA in susceptible contacts receiving HAV or IG versus those without PEP were calculated. There were 3550 exposed persons in the outbreaks studied: 2381 received one dose of HAV vaccine (Hepatitis A or hepatitis A+B), 190 received IG, and 611 received no PEP. 368 exposed subjects received one dose of HAV vaccine and IG simultaneously and were excluded from the study. The effectiveness of PEP was 97.6% (95% CI 96.2-98.6) for HAV vaccine and 98.3% (95% CI 91.3-99.9) for IG; the differences were not statistically significant (p = 0.36). The elevated effectiveness of HAV vaccination for PEP in HA outbreaks, similar to that of IG, and the long-term protection of active immunization, supports the preferential use of vaccination to avoid secondary cases.

Changing risk profile of hepatitis A in The Netherlands: a comparison of seroprevalence in 1995-1996 and 2006-2007

The prevalence of antibodies to hepatitis A virus (HAV) was assessed in a nationwide sample (n=6229) in The Netherlands in 2006-2007, and compared to the seroprevalence in a similar study in 1995-1996 (n=7376). The overall seroprevalence increased from 34% in 1995-1996 to 39% in 2006-2007, mainly due to vaccination of travellers and an increased immigrant population. Risk factors remain travelling to, and originating from, endemic regions, and vaccination is targeted currently at these risk groups. Our results show a trend of increasing age of the susceptible population. These people would also benefit from HAV vaccination because they are likely to develop clinically serious symptoms after infection, and are increasingly at risk of exposure through imported viruses through foods or travellers. The cost-effectiveness of adding elderly people born after the Second World War as a target group for prophylactic vaccination to reduce morbidity and mortality after HAV infection should be assessed.

CD40mAb adjuvant induces a rapid antibody response that may be beneficial in post-exposure prophylaxis

Active vaccination can be effective as a post-exposure prophylaxis, but the rapidity of the immune response induced, relative to the incubation time of the pathogen, is critical. We show here that CD40mAb conjugated to antigen induces a more rapid specific antibody response than currently used immunological adjuvants, alum and monophosphoryl lipid A.