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The efficacy of vaccine when time since exposure is prolonged (more than 1 week from onset of illness in the index case) is unknown, but is likely to be significantly lower than human normal immunoglobulin (HNIG). We estimated the number of additional secondary cases that may occur through giving vaccine instead of HNIG to contacts of cases of hepatitis A who are identified more than 1 week after onset in the index case. This was calculated for different levels of vaccine efficacy, assuming HNIG efficacy to be 80-90%. The number of households that need to be treated to prevent one secondary case was calculated using estimates of secondary attack ratios (AR). If more than 1 week has elapsed from onset of illness in the index case, for an average household size of 2.3 people, a vaccine efficacy of 50% and an AR of 10-25%, 8-26 households would need to be treated with vaccine before one additional secondary case would be observed. As UK public health professionals manage around one hepatitis A case per month, it would take from 8 months to over 2 years for them to observe one additional case amongst contacts using vaccine rather than HNIG. It is unlikely that an average practitioner would notice if vaccine were 30% less effective than HNIG. Public health practice and advice to patients and contacts should be based on evidence as well as experience.

Objective: To study the use of hepatitis A virus (HAV) vaccination in controlling an outbreak of HAV in inner-city Bristol among injecting drug users (IDUs). To study whether hepatitis C virus (HCV) and hepatitis B virus (HBV) co-infection increases morbidity., Design: Community-based cohort study., Setting: Avon Health Authority area, UK., Participants: All laboratory-confirmed cases of HAV infection notified in 2000., Intervention: Administration of a targeted vaccination, education and liaison programme., Main Outcome Measures: Number of cases of HAV before and after introduction of HAV vaccination programme. Mortality and number of patients requiring hospital admission. Association of HCV and HBV co-infection with hospital admission., Results: Ninety cases of HAV were reported in the first 6 months of 2000, of whom a substantial number were IDUs and/or inner-city hostel residents. In the second 6 months of 2000, following the introduction of a vaccination programme among homeless people, hostel residents, and IDUs, the number of HAV cases fell to 33. Sixteen patients had evidence of HCV co-infection. No patient had chronic HBV infection. Two patients died as a result of HAV, and two subsequently died from drug misuse. Fifty-six per cent of HCV-co-infected patients required admission to hospital compared with 28% non-HCV-co-infected patients., Conclusions: This is the first reported successful use of vaccination to control an outbreak of HAV in a population of IDUs and to prevent transmission to the wider population. HCV co-infection appears to increase the severity of HAV illness, as demonstrated by increased incidence of hospital admission.

Since 2001 there have been significant outbreaks of hepatitis A virus (HAV) across South Yorkshire, largely in intravenous drug users, and HAV infection has been reported to be an increasing problem in England and Scotland during this time. This paper reports a brief investigation to clarify current HAV epidemiology in England and Wales. The epidemiology of HAV in England, but not yet Wales, has recently changed. Laboratory reports now show that most cases are occurring in young adults, mainly young men, and that the commonest reported risk group is injecting drug users. That cases may now be concentrated in injecting drug users is supported by reports from consultants in communicable disease control (CsCDC). These detail fourteen outbreaks in England in 2002 alone, all involving injecting drug users. Links to prisons and to the homeless, usually those in hostels, were also common. A combined Hepatitis A/B vaccine is readily available and we recommend that this now be used to extend the national immunisation programme against Hepatitis B in injecting drug users to include HAV.

A prolonged outbreak of hepatitis A infection amongst drug users in Suffolk prompted a study of the natural immunity against hepatitis A in this population, and a retrospective analysis of the relationship between specific drug-taking behaviours and the risk of hepatitis A infection. Prior to the outbreak, age-specific seroprevalence of hepatitis A IgG in drug users was similar to that amongst blood donors in the region. Of those without effective immunity, intravenous drug users, multiple drug users and those injecting frequently were more likely to have developed hepatitis. The reported frequency of equipment sharing and the number of injecting partners were not related to the risk of infection. The potential for blood-to-blood, and a suggested faecal-blood transmission were considered to be important in propagating the outbreak in this population. We suggest that a single dose of hepatitis A vaccine administered opportunistically should be used in outbreaks involving drug users.

Increasing Hepatitis A (HAV) infection has been reported in communities in which there is a high level of intravenous drug use. Several cases were identified in a local prison and since the risk of transmission within the prison was felt to be high, it was decided to determine the prevalence of HAV antibodies in the prison population and therefore the number of susceptible inmates. Oral fluid was collected from 269 prisoners for testing for antibodies to HAV. Both IgM and IgG anti-HAV were assessed so that the percentage susceptible and the number recently infected could be ascertained. Eight inmates had evidence of a recent infection. Of the remaining 261, only 56 (21%) were immune to HAV. Therefore vaccination against HAV in addition to HBV should be considered for intravenous drug users and for prisoners remanded from a community where infection is known to be occurring.

An outbreak of hepatitis A involved more than 50 residents of a group of villages in the late spring and summer of 1989. The only food that was common to all the laboratory-confirmed cases was bread, purchased either unwrapped or as rolls, sandwiches or filled rolls, and supplied either directly from one shop or indirectly through its subsidiary outlets. It was concluded that this bread was the most likely vehicle of transmission of the hepatitis A virus and that the bread was contaminated by soiled hands which were inadequately washed because of painful skin lesions. Comprehensive control measures were successful in limiting further spread of the infection. This outbreak highlights the transmissibility of hepatitis A virus on food. The use of disposable gloves when handling food which is to be consumed without further cooking would prevent transmission of this or other infectious agents by this route.

Clinical hepatitis, diagnosed as being caused by virus type A by tests for specific immunoglobulin M, has been reported from laboratories in England, Wales and Ireland since 1980. There were 25541 reports in the following 9 years, a yearly average of 2838. A 7-year cycle is suggested by peaks in the numbers of reports of 4502 in 1982 and 4167 in 1988 with a continuing rise in 1989. Contact with other cases of acute hepatitis was recorded for 3899 patients (15%) of which 2497 (64%) were in families, 258 (7%) were in schools, 94 (2%) were in institutions/hospitals, 197 (5%) were in the neighbourhood, while 140 (4%) were contacts at work or socially. A possible food source was recorded for 122 (3%) with shellfish being specified in 56 cases. Recent travel abroad was reported for 3692 patients (15%) of whom 3027 (82%) had visited areas of high prevalence for hepatitis A. About half of them had been to the Indian sub-continent, in strong contrast to visits abroad by the general population each year of which only 7% of the 22 million visits are to areas of high prevalence for hepatitis A. Association with the Indian sub-continent was particularly high for children.

Early in 1981, cases of hepatitis possibly associated with the consumption of cockles were reported mainly from south-east England. A case-control study was undertaken in 19 local authority districts. Between Nov. 1, 1980, and April 30, 1981, 424 cases of infective jaundice were formally notified and case-finding yielded 26 additional cases. 42.6% of those with hepatitis and 17.5% of the controls reported consumption of cockles. There was a statistically significant association between infective jaundice and the consumption of cockles but not other sea foods. The cockles had probably been insufficiently processed and stricter controls on treatment of such shellfish are needed.