Primary Hepatitis A vaccination failure is a rare although possible event: results of a retrospective study

Trends and risk factors of hepatitis A in Catalonia after the introduction of a hepatitis A+B vaccination programme

At the end of 1998, universal hepatitis A+B vaccination of 12 year olds was introduced in Catalonia. The aim was to examine trends in hepatitis A during 2005-2015 and assess risk factors by age group. We carried out an observational epidemiological study of the incidence and risk factors of hepatitis A reported to the surveillance system. Information on exposure was recorded for each case for the 2-6 weeks before symptom onset. Spearman's coefficient was used to evaluate the trends of rates. The chi-square test was used to compare categorical. We studied 2621 hepatitis A cases; the age mean was 26.6 years (SD=18.2), and >50% of cases were in the 20-49 years age group. The incidence decreased from 3.28/100 000 in 2005 to 1.50/100 000 in 2015. The rate for women decreased over time (P = .008), but the reduction was not significant in men (P = .234). Men consistently had higher rates than women with the biggest difference being in the 20-34 years age group (rate 8.8 vs 2.8). The greatest risk factor was travel to an endemic country (42.1%) in the 0-19 years age group and male-to-male sexual contact (18.6%) in the 20-49 years age group. The case fatality rate in adults aged >49 years was 0.4%. In conclusion, the vaccination programme of preadolescents resulted in a reduction in hepatitis A cases. However, a significant amount of cases still appear in immigrants and men who have sex with men. Hepatitis A in adults is an emerging health problem that will require new strategies.

Hepatitis A in Switzerland: An analysis of 29 years of surveillance data and contemporary challenges

BACKGROUND

Hepatitis A (HA) incidence declined in most European countries in the past decades. We analysed HA notification data for Switzerland of 29 years looking for disease- and notification system-related factors possibly contributing to observed trends.

METHOD

Notification data were descriptively analysed using five time intervals (1988-1993, 1994-1999, 2000-2005, 2006-2011, 2012-2016); and notification rates were calculated.

RESULTS

From 1988 to 2016, the HA notification rate decreased from 9.5 to 0.5 per 100'000 population in Switzerland. Median age and the proportion of hospitalised cases increased over time. In the 1988-1993-time period, intravenous drug use was the most frequently mentioned risk exposure while consumption of contaminated food/beverages was most frequently mentioned in the 2012-2016-time period.

CONCLUSIONS

Notification data does not allow reliably identifying current risk groups (e.g. travellers) due to low case numbers, limited availability and reliability of information. It is important to document changes in the surveillance system for later analyses and interpretation of long-term trends. Population susceptibility likely increases underlining the importance of continued and continuous surveillance and prevention efforts despite decreasing case numbers. Operational research is recommended to further investigate observed trends of HA and to enhance the abilities for decision making from Swiss HA surveillance data.

Hepatitis A virus genotype distribution during a decade of universal vaccination of preadolescents

A universal vaccination program among preadolescents was implemented in Catalonia, Spain, during the period of 1999-2013 and its effectiveness has been clearly demonstrated by an overall significant attack rate reduction. However, reductions were not constant over time, and increases were again observed in 2002-2009 due to the occurrence of huge outbreaks. In the following years, in the absence of large outbreaks, the attack rate decreased again to very low levels. However, an increase of symptomatic cases in the <5 age group has recently been observed. This is an unexpected observation since children younger than 6 are mostly asymptomatic. Such a long vaccination campaign offers the opportunity to analyze not only the effectiveness of vaccination, but also the influence of the circulating genotypes on the incidence of hepatitis A among the different age groups. This study has revealed the emergence of genotype IC during a foodborne outbreak, the short-lived circulation of vaccine-escape variants isolated during an outbreak among the men-having-sex-with-men group, and the association of genotype IIIA with the increase of symptomatic cases among the very young. From a public health perspective, two conclusions may be drawn: vaccination is better at an early age, and the vaccination schedule must be complete and include all recommended vaccine doses.

Hepatitis A Virus among Drug Users and the Role of Vaccination: A Review

In countries with advanced economies better health and hygiene conditions, along with the introduction, in some cases, of global vaccination, have relegated most viral hepatitis to marginal social groups and, in particular, drug users (DUs). The availability of safe and effective vaccines for hepatitis A virus (HAV) and B (HBV) may play a major role in combating this phenomenon. Despite the availability of a safe and effective vaccine for over a decade and the recommendations of international health organizations, vaccinations against HAV among DUs are not as widely known and available as are HBV vaccinations. The purpose of this review article is to present the most significant data in the literature on the prevalence of HAV among DUs and the role of targeted vaccination. To our knowledge, the present article is the first to solely deal with vaccination against HAV in DUs. Immunization after the administration of anti-HAV vaccine has been demonstrated in DUs even if they have responded significantly less than either the general population or carriers of chronic liver disease. All the vaccines were well tolerated and adherence to the vaccine schedule was good. Further studies are needed to optimize the timing and doses of vaccine to be administered to DUs, especially to assess adherence and antibody persistence. Vaccination campaigns are feasible among DUs and have proven to be highly cost-effective.

An outbreak of hepatitis A affecting a nursery school and a primary school

Between March and June 2008, 12 cases of hepatitis A were notified in Winchester. Cases were from a primary school and a nursery school with no direct linkage. Hepatitis A virus (HAV) RNA sequenced from nine cases confirmed the strain in both schools to be identical. The outbreak could have affected three other schools and a maternity unit and was controlled by immunization and screening of neonates in the maternity unit by dried blood spots. No neonates were infected and no further cases were reported until 5 months later when the index case's mother became infected with same strain of virus associated with the outbreak despite vaccination. Neither the source of the outbreak or the subsequent infection of the index case's mother was identified; however, with the timing of the cases continued transmission in the community by children with asymptomatic infection or a recurrent source cannot be ruled out.