Prevaccination Screening Research Articles

Clinical and immune response to undiluted and diluted smallpox vaccine.

To assess clinical reactions, immune responses and adverse events to undiluted, three- and sixfold diluted Lister strain vaccine stockpiled in Switzerland. A prospective, triple-blinded, randomised, parallel group clinical trial was performed. From 2001 to 2007 104 persons with an indication for vaccinia vaccination were recruited. They had a median age of 33 years (range 18-65), 56 (53.8%) were re-vaccinees and 48 (46.2%) primary vaccinees. There was no statistically significant variation in the proportion of revaccinees between diluted and undiluted vaccine groups (75% vs 51%, p = 0.118). With an overall clinical take rate (major reaction) of 97.1% the majority of the vaccinia-naïve participants exhibited an at least fourfold increase of neutralising antibody titres (32/38, 84.2%) post-vaccination. Interestingly this proportion was lower among re-vaccinees (29/46, 63.0%, p = 0.048). No significant difference was observed in the take rate or at least fourfold seroconversion rate between the threefold and sixfold diluted vaccine doses. Adverse events were reported by 98 (94.2%) participants, not accounting for itching at the vaccination site. Subjects requiring immunisation were successfully (re-) vaccinated with undiluted as well as with three- or sixfold diluted vaccinia vaccine. Our findings complement previous studies with respect to the clinical take rate and immune response. The rate of adverse events was substantial but not unexpected and no severe adverse events occurred. In conclusion, the existing smallpox vaccine stockpile might be expanded by administering three- or sixfold diluted vaccine doses combined with a careful pre-vaccination screening and extensive instructions to vaccinees.

Clinical and immune response to undiluted and diluted smallpox vaccine.

To assess clinical reactions, immune responses and adverse events to undiluted, three- and sixfold diluted Lister strain vaccine stockpiled in Switzerland. A prospective, triple-blinded, randomised, parallel group clinical trial was performed. From 2001 to 2007 104 persons with an indication for vaccinia vaccination were recruited. They had a median age of 33 years (range 18-65), 56 (53.8%) were re-vaccinees and 48 (46.2%) primary vaccinees. There was no statistically significant variation in the proportion of revaccinees between diluted and undiluted vaccine groups (75% vs 51%, p = 0.118). With an overall clinical take rate (major reaction) of 97.1% the majority of the vaccinia-naïve participants exhibited an at least fourfold increase of neutralising antibody titres (32/38, 84.2%) post-vaccination. Interestingly this proportion was lower among re-vaccinees (29/46, 63.0%, p = 0.048). No significant difference was observed in the take rate or at least fourfold seroconversion rate between the threefold and sixfold diluted vaccine doses. Adverse events were reported by 98 (94.2%) participants, not accounting for itching at the vaccination site. Subjects requiring immunisation were successfully (re-) vaccinated with undiluted as well as with three- or sixfold diluted vaccinia vaccine. Our findings complement previous studies with respect to the clinical take rate and immune response. The rate of adverse events was substantial but not unexpected and no severe adverse events occurred. In conclusion, the existing smallpox vaccine stockpile might be expanded by administering three- or sixfold diluted vaccine doses combined with a careful pre-vaccination screening and extensive instructions to vaccinees.

Monitoring the Safety of a Smallpox Vaccination Program in the United States: Report of the Joint Smallpox Vaccine Safety Working Group of the Advisory Committee on Immunization Practices and the Armed Forces Epidemiological Board

In December 2002, the Centers for Disease Control and Prevention's Advisory Committee on Immunization Practices and the Department of Defense Armed Forces Epidemiological Board formed a joint Smallpox Vaccine Safety Working Group (SVS WG) to provide independent safety oversight for smallpox vaccination safety-monitoring systems. From January 2003 through June 2004, the SVS WG reviewed individual and aggregate safety data on postvaccination adverse events. Serious adverse events were rare because of careful education, prevaccination screening, and strict attention to vaccination-site management. Recent vaccinees safely cared for high-risk patients, adhering to recommended site care. Human immunodeficiency virus-infected individuals without severe immunosuppression had uncomplicated vaccination reactions. Epidemiological studies supported a causal relationship between myocarditis and/or pericarditis and smallpox vaccination. Data supported neutrality regarding hypothesized causal associations between vaccination and dilated cardiomyopathy or ischemic cardiac disease. The SVS WG concurs with recommendations to defer from vaccination any person with >/=3 ischemic cardiac disease risk factors.

Smallpox vaccination and ischemic coronary events in healthy adults

Although smallpox vaccine-associated myopericarditis has been reported, the risk of cardiac ischemic events remains uncertain. We identified personnel receiving the smallpox vaccination and compared them to a historical referent population. The rate of cardiac ischemia diagnoses in the 30 days following smallpox vaccination was 140.1 per 100,000 person-years, compared to 143.5 per 100,000 person-years in referent group (RR 1.0 [95% CI: 0.7–1.4]). The rate of cardiac ischemic events in vaccinees was 121.4 per 100,000 person-years before and 175.7 after adopting pre-vaccination cardiac screening (RR 1.4 [95% CI: 0.8–2.7]). Implementation of pre-vaccination cardiac risk factor screening was not associated with a reduction in cardiac events.

Measles, rubella, mumps, and varicella seroprevalence among health care workers in Turkey: Is prevaccination screening cost-effective?

To investigate the immune status of health care workers (HCWs) against measles, rubella, mumps, and varicella zoster (MMRV) in Turkey and to define an appropriate vaccination program among HCWs. Voluntary HCWs from a children's hospital and a general hospital were included in the study between March and May 2005. The specific IgG antibodies against MMRV viruses were screened by ELISA. Three hundred sixty-three HCWs participated in the study; 186 (51%) were physicians, 118 (33%) were nurses, 36 (10%) were housekeeping staff, and 23 (6%) were medical technicians. The proportion of HCWs who had antibodies against measles was 98.6%; rubella, 98.3%; mumps, 92.2%; and varicella, 98%. No association was found between the susceptibility to at least 1 of MMRV virus infections and gender, age, duration of work, profession, and department of work in analysis either among the whole study group, or each hospital. The positive predictive value for the history of varicella was 100%, whereas it was 92% for MMR. The cost of vaccination for varicella was significantly expensive without screening before vaccination. However, there was not much difference for MMR infections. A policy based on obtaining the history of varicella infection from the staff and then screening the ones with negative history and vaccination of only seronegative HCWs was found to be appropriate.

Generalized Vaccinia, Progressive Vaccinia, and Eczema Vaccinatum Are Rare following Smallpox (Vaccinia) Vaccination: United States Surveillance, 2003

Generalized vaccinia (GV), progressive vaccinia (PV), and eczema vaccinatum (EV) are adverse reactions following smallpox vaccination. We investigated all reports suggestive of GV, PV, or EV among United States civilian smallpox vaccinees during 2003 and applied standard case definitions. We identified 29 reports of possible GV among 38,440 vaccinees; 2 (7%) of the reports met the case definition. One case of GV was confirmed by identifying vaccinia from a lesion distant from the vaccine site using polymerase chain reaction. The other case was classified as probable GV, because confirmatory testing was not done. We identified 3 potential EV cases and 7 potential PV cases, none of which met the standard case definition. GV, PV, and EV were rare or absent following smallpox vaccination after careful screening of potential vaccinees. GV may be difficult to distinguish from other rashes, and confirmatory testing is recommended. Careful prevaccination screening probably contributed to the low incidence of these adverse reactions following smallpox vaccination.

Control strategies for Q fever based on results of pre‐vaccination screening in Victoria, 1988 to 2001

Objective:Data from Q fever prevaccination screening were analysed to determine the level of agreement between the two tests of immunity and between disease or vaccination history and immunity, trends in proportion of participants immune to Q fever, and the annual risk of infection.Method:Data from nearly 10,000 screening episodes between July 1988 and June 2001 on Victorian workers at high risk were assessed.Results:Most participants were male (86%) and employed in Victorian abattoirs (81%). Agreement between results of tests for immunity was ‘fair’ (k=0.52). Selfreported history of vaccination or infection was a poor predictor of immunity. The proportion of positive blood and skin tests increased with years of exposure to animals/meat, but decreased over the 13‐year period with shorter exposures. Hence the percentage requiring vaccination increased from 50% in 1998 to 90% in 2001. The average annual risk of infection among abattoir workers was 45.0 per 1,000 (95% CI 42.3–47.6), and 62.6 per 1,000 (95% CI 57.5–67.7) over the first 10 years of exposure.Conclusions:This is the first Australian study to estimate the annual risk of Q fever infection in abattoir workers. The study confirmed previous findings of poor agreement between screening tests and predictive value of history of vaccination/exposure. Up to 90% of new entrants in high‐risk workplaces will be susceptible to Q fever and require vaccination.Implications:Systematic post‐marketing surveillance is needed to monitor adverse events to the vaccine, duration of protection and possible reasons for vaccine failures.

Genetic variability of hepatitis A virus isolates in Rio de Janeiro: implications for the vaccination of school children

The epidemiology of hepatitis A virus (HAV) infection is shifting from high to intermediate endemicity in Brazil, resulting in increased numbers of susceptible individuals and a greater potential for the emergence of outbreaks. Universal vaccination against HAV has been recommended for children, but updated sero-epidemiological data are necessary to analyze the level of natural immunity and to identify candidates for preventive measures. In addition, more molecular studies are necessary to characterize the genotypes involved in HAV infections and outbreaks. Sera from 299 school children (5-15 years old) and 25 school staff members, collected during an outbreak of HAV at a rural public school in June 2000, were tested for IgM and total anti-HAV antibodies (ELISA). Viral RNA was amplified by RT-PCR from anti-HAV IgM-positive sera and from 19 fecal samples. Direct nucleotide sequencing of the VP1/2A region was carried out on 18 PCR-positive samples. Acute HAV infection was detected by anti-HAV IgM in 93/299 children and in 3/25 adult staff members. The prevalence of total anti-HAV antibodies in IgM-negative children under 5 years of age was only 10.5%. HAV-RNA was detected in 46% IgM-positive serum samples and in 16% stool samples. Sequence analysis showed that half the isolates belonged to subgenotype IA and the other half to IB. On the basis of these data, mass vaccination against HAV is recommended without prevaccination screening, especially for children before they enter school, since nearly 90% of the children under 5 years were susceptible. Molecular characterization indicated the endemic circulation of specific HAV strains belonging to subgenotypes IA and IB.

Prevalence of measles, rubella, mumps, and varicella antibodies among healthcare workers in Japan.

To evaluate the immune status of healthcare workers (HCWs) against measles, rubella, mumps, and varicella in Japan, and to promote an adequate vaccination program among HCWs. University of Tokyo Hospital. Eight hundred seventy-seven HCWs. Serologic screening for measles, rubella, mumps, and varicella was performed on HCWs. Antibodies against measles, rubella, and mumps were detected using hemagglutination inhibition (HI) assay ($4.20 per test). If serum was negative by HI assay, enzyme-linked immunosorbent assay (EIA) was performed ($12.60 per test). Anti-varicella antibodies were detected by EIA only. Among tested HCWs, 98.5%, 90.4%, 85.8%, and 97.2% had immunity to measles, rubella, mumps, and varicella, respectively. All those born before 1970 were seropositive for measles. However, individuals susceptible to rubella, mumps, and varicella were present in all age groups. The sensitivities and negative predictive values of HI assay compared with EIA were 86.6% and 11.3% for measles, 99.1% and 92.2% for rubella, and 47.8% and 24.1% for mumps, respectively. For measles and mumps, prevaccination screening by HI assay in combination with EIA led to significant savings compared with EIA only. In contrast, it was estimated that prevaccination screening using only HI assay would be more economical for rubella. Aggressive screening and vaccination of susceptible HCWs was essential regardless of age. Prevaccination serologic screening using a combination of HI assay and EIA was more economical for measles and mumps.

Prevalence of previous hepatitis A virus infection in renal transplant patients with hepatitis C: evidence of persistent anti-hepatitis A virus immune response

Data concerning the prevalence of hepatitis A virus (HAV) infection among kidney transplant recipients are scarce. There is little information concerning natural immunity acquired after acute HAV infection. In most renal transplant recipients, anti-HAV antibodies are not detectable after vaccination; it is reasonable to suppose that immunosuppressive therapy interferes with the immunity. The objective of this study was to evaluate, in an endemic area, the prevalence of anti-HAV immunoglobulin (Ig)G in renal transplant recipients with chronic hepatitis C virus (HCV) infection. The prevalence of anti-HAV IgG was assessed in 40 HCV-positive renal transplant recipients. This group showed a 90% prevalence of previous HAV infection. These findings suggest that in an endemic area, the prevalence of previous HAV infection is high, even among immunosuppressed patients. HAV antibodies acquired after natural infection are detectable even after the onset of immunosuppressive therapy. These data should be considered when renal transplant recipients are considered for HAV vaccination. Prevaccination screening of renal transplant recipients must follow the same guidelines as those for immunocompetent subjects.

LUM ET AL. RESPOND

Diamond correctly points out the difficulty of making comparisons between the presence of hepatitis B surface antibodies (anti-HBs) among persons reporting prior immunizations (Seattle Young Men’s Survey [YMS]) and anti-HBs seroconversion measured after a documented immunization series (the UFO Study). Recall bias and waning anti-HBs could certainly have contributed to the lower proportion (70%) of subjects with isolated anti-HBs that YMS investigators observed.1 In the UFO Study, 62% of young injection drug users (IDUs) who reported 3 prior immunizations demonstrated isolated anti-HBs. We reported anti-HBs seroconversion in 78% of young IDUs after 3 doses of a monovalent recombinant hepatitis B virus (HBV) vaccine.2 Physiological factors that may blunt the immune response include lifestyle (e.g., smoking and obesity), biological factors (e.g., male sex and older age), and the coexistence of other immune-mediated diseases.3 Among homosexual and bisexual men, HIV infection has been associated with poorer HBV vaccine responses.4 The role of hepatitis C virus (HCV) antibody status in suboptimal HBV vaccine responses is still controversial. Some studies have reported an association,5,6 while others have found none.7,8 Our observation of a lower vaccine response among anti-HCV–positive subjects occurred in a subset too small for statistical significance. However, we plan to investigate this issue further in a new trial of hepatitis vaccine adherence among young IDUs in San Francisco. We agree with Diamond that prevaccination screening of high-prevalence populations for prior infection or immunity makes sense. At the San Francisco STD Clinic, screening was cost saving when seroprevalence was greater than 22% (J. D. Klausner, MD, MPH, STD Prevention and Control Services, San Francisco Department of Public Health; written communication; September 17, 2003). Because many young IDUs and young men who have sex with men are lost to follow-up and cannot afford to pay for either blood tests or vaccines, public health providers must often decide whether to assume these costs. Some providers have chosen a catch-as-catch-can approach, administering the first vaccine dose on the day of prevaccination screening. Finally, while understanding the factors that impair vaccine responses is important, 78% effectiveness is not all that bad. Future HIV vaccine candidates may be licensed with much lower partial efficacy.9 Strategies to improve vaccine series completion among high-risk adolescents and adults arguably present the greater challenge for the prevention of HBV transmission in the United States. Those strategies are likely to be useful not just for the delivery of HBV vaccines but also for the delivery of promising HIV vaccine candidates in the future.

An economic assessment of pre-vaccination screening for hepatitis A and B.

The availability of a single vaccine active against hepatitis A and B may facilitate prevention of both infections, but complicates the question of whether to conduct pre-vaccination screening. The authors examined the cost-effectiveness of pre-vaccination screening for several populations: first-year college students, military recruits, travelers to hepatitis A-endemic areas, patients at sexually transmitted disease clinics, and prison inmates. Three prevention protocols were examined: (1) screen and defer vaccination until serology results are known; (2) screen and begin vaccination immediately to avoid a missed vaccination opportunity; and (3) vaccinate without screening. Data describing pre-vaccination immunity, vaccine effectiveness, and prevention costs borne by the health system (i.e., serology, vaccine acquisition, and administration) were derived from published literature and U.S. government websites. Using spreadsheet models, the authors calculated the ratio of prevention costs to the number of vaccine protections conferred. The vaccinate without screening protocol was most cost-effective in nine of 10 analyses conducted under baseline assumptions, and in 69 of 80 sensitivity analyses. In each population considered, vaccinate without screening was less costly than and at least equally as effective as screen and begin vaccination. The screen and defer vaccination protocol would reduce costs in seven populations, but effectiveness would also be lower. Unless directed at vaccination candidates with the highest probability of immunity, pre-vaccination screening for hepatitis A and B immunity is not cost-effective. Balancing cost reduction with reduced effectiveness, screen and defer may be preferred for older travelers and prison inmates.

An economic assessment of pre-vaccination screening for hepatitis A and B

An economic assessment of pre-vaccination screening for hepatitis A and B

Bioterrorism Preparedness: The Smallpox Vaccine Debate

On December 13, 2002 President Bush announced the White House plan to vaccinate approximately 500,000 military and civilian Americans against smallpox.1 The objective of the plan is to protect the people of the United States from the threat of smallpox as a potential bioterrorism agent employed by hostile groups or governments. On the civilian side, the plan is to form volunteer Smallpox Response Teams who are able to provide care to those affected in the event of a smallpox outbreak. These teams are composed of health care workers and others who may provide care to patients exposed to smallpox. At the present time, the plan does not recommend vaccination for the general public. In this issue of Clinical Medicine & Research, Belongia and Naleway2 present an argument that supports a limited smallpox vaccination program. This is based not only on the calculated risk of a smallpox bioterrorism attack as presented recently by Bozzette et al.,3 but also the potential risk of vaccine-related events. These risks do not only apply to those who receive the vaccine but also those close contacts of vaccinated individuals. The vaccination plan should be based on the benefits of the vaccine and the assessment of risks associated with it. Several experts are not in agreement with the White House plan.4 The disagreement is based on previous, well-documented experience with the best methods to prevent the transmission of smallpox. In contrast to a large-scale population vaccination program, it has been shown that a program such as “ring” vaccination can be more effective.5 The vaccine benefit is not clearly identified based on our knowledge of a disease that does not exist, whereas, in a post-event setting there is clear reason to accept the risks. As documented by Belongia and Naleway, adverse events associated with smallpox vaccination are very uncommon and range from generalized vaccinia, to death. Other adverse events include eczema vaccinatum, encephalitis and progressive vaccinia. There are also adverse events including death due to secondary transmission of vaccinia, transmission associated with close contact to persons who recently received the vaccine. Published reports document twenty-six cases of secondary transmission within families. Three cases of the secondary transmission were fatal (11.5%). Eighty-five, secondary cases of nosocomial vaccinia are reported in the literature, with nine associated deaths (10.6%).6 The following adverse events were reported following the recent vaccination of more than 100,000 military personnel: encephalitis (n=2), myocarditis (n=1), generalized vaccinia (n=2) and ocular vaccinia (n=1).7 To date, nine moderate-to-severe adverse events were reported following the recent vaccination of 19,919 civilian and public health care workers. These include; generalized vaccinia (n=1), angina (n=2), headache and dizziness (n=1), cholecystitis (n=1), hypertension (n=1), vomiting and diarrhea (n=1), exacerbation of COPD and diarrhea (n=1), myocarditis (n=1).8,9,10 Five cases of transmission to close contacts of military vaccinees were reported, two of these cases were diagnosed as ocular vaccinia. This low incidence of adverse events may be attributed to the pre-vaccination screening method that was used in order to scrutinize those selected to receive the vaccine and identify those at risk of developing adverse events. The role of hospitals and physicians in bioterrorism preparedness is paramount. This readiness should not be limited to ensuring the safety and health of those who receive the smallpox vaccine and their contacts, but should include plans to handle actual bioterrorism events including a smallpox attack. Health care providers, including physicians, should develop a thorough understanding of bioterrorism agent characteristics, diagnostic and treatment options. Ultimately, this may be the best method to prevent and limit the impact of these events, either actual or hoax. Hospitals must enhance diagnostic capabilities and epidemiologic surveillance programs. Emergency preparedness programs must be modified to include bioterrorism. Above all, we must all educate ourselves. We must also not forget that an enhanced public health infrastructure will serve this nation well for the control of the disease, no matter the origin.

Management of vaccination - related anaphylaxis

Anaphylaxis is a systemic, immediate hypersensitivity reaction due to IgE mediated immunologic release ofmediators from mast cells and basophils. Features of severe condition are obstruction of the upper airway from tissueswelling, marked bronchospasm, and hypotension. In vaccination related anaphylaxis, optimal management begins withprevention: prevaccination screening including questions about possible allergy to any component of vaccine, and anticipationof anaphylaxis by observation at least 15 minutes following vaccination are very important. The essential treatment isprompt administration of adrenaline. Since hypotension is due to a shift of fluid from intravascular to extravascular space, themainstay of treatment should be the restoration of intravascular volume. Since anaphylaxis can be biphasic administration ofcorticosteroid in preventing late phase reaction can be postulated.

Hepatitis A seroprevalence in Slovene travellers.

Hepatitis A virus (HAV) infection rates used to be very high in the past [1]. In the economically developed countries, HAV infection rates and the proportion of people with immunity to HAV decreased as a result of improved sanitation [2, 3]. There is a scarcity of information on the prevalence rates of anti-HAV in the Central European countries [4, 5]. Travellers to non-industrialized areas are exposed to infections that do not exist, or occur very rarely in their home country, such as HAV infection [6]. Nonimmune persons are effectively protected against HAV infection by timely vaccination. Immunization is not required in HAV seropositive travellers. The purpose of the study was to ascertain the seroprevalence of antibodies to HAV in adult Slovene travellers, and to determine whether prevaccination screening can reduce unnecessary vaccination. From the beginning of July 1999 to the end of October 1999, screening for antibodies to HAV was offered to all travellers aged 18–57 years who presented for immunization or malaria chemoprophylaxis at the travel clinic of the Institute of Public Health. The study included travellers born in Slovenia who had had no previous vaccination against HAV and denied having had known HAV infection. They were notified of test results. The travellers were categorized by the year of birth into the following eight groups: 1942–1946, 1947–1951, 1952–1956, 1957–1961, 1962–1966, 1967–1971, 1972–1976, 1977– 1981. On the basis of the ascertained seroprevalence we determined at what age prevaccination screening for HAV antibodies is cost-effective. Costs of the primary vaccination and booster immunization at months 6–12 were estimated. The total cost, i.e. the price of HAV vaccine plus the cost of vaccination, amounted to 97.8 EUR. The cost of antibody test was estimated to be 28.2 EUR. Over a period of 4 months, we tested 328 travellers (178 men and 150 women) with no history of acute HAV infection or previous vaccination against HAV. Altogether 103 (31.4%) subjects tested positive for HAV antibodies. Seropositivity rates are presented in Table 1. Seropositivity increased with age (p-value 0.001, v-test). Among the travellers born before 1962, 55.6% tested positive for anti-HAV. In contrast, a vast majority of persons (93.7%) born in 1971 and later who gave no history of infectious jaundice showed no immunity to HAV. Our observations are comparable to the results of a similar American study of travellers with no history of hepatitis A before vaccination [7]. It showed that solely 16.6% of persons born in industrialized countries were seropositive for HAV. The HAV seroprevalence rate was higher (32.1%) in individuals travelling frequently to economically less developed countries, and extremely high (82.7%) in people born in nonindustrialized countries. Prevaccination screening is considered cost-effective when the cost of vaccinating the entire population is higher than the cost of testing plus the cost of vaccinating non-immune individuals [8]. Considering the cost of vaccination of 97.8 EUR and 28.2 EUR for testing, the screening is economically valid for a population with a seropositivity rate of 29 per cent. The calculation based on the price of vaccine and cost of testing showed that vaccination without previous testing is cost-effective in subjects born after 1961. As previously mentioned, hepatitis A has become rare in the central part of Europe, too [4, 5]. The number of notified hepatitis A cases in Slovenia has been on a constant decline, particularly since 1990 (Figure 1) [9]. The decline is not attributable solely to the changed notification system, because the reporting

Screening travelers for hepatitis A antibodies: an observational cost-comparison study of vaccine use.

To measure the seroprevalence of antibodies to hepatitis A virus (anti-HAV) in a health plan population of travelers and to determine whether prevaccination screening for anti-HAV can reduce unnecessary vaccination and thus promote the most effective, economic use of hepatitis A vaccine. Observational, cost-comparison study. Central injection clinic of a health maintenance organization medical center. Five hundred twenty-seven adults who denied having previous hepatitis A or vaccination. MAIN OUTCOME MEASURES Subgroups with the greatest prevalence of anti-HAV seen between June 1995 and April 1996 for immunizations before traveling to nonindustrialized countries. Relative costs of their screening and immunization. The presence of anti-HAV precluded the need for vaccination in 148 subjects (28.1%). The highest prevalence of anti-HAV (82.7%) was found in subjects born in nonindustrialized countries (62/75), in subjects who had previously traveled to areas of endemic hepatitis A (32.1% [135/420]), and in subjects born before 1945 (29.2% [92/315]). Costs of screening and vaccinating travelers were cheapest if prevaccination antibody sera testing was limited to subjects born in nonindustrialized countries and those born before 1945. Prevaccination screening of travelers for hepatitis A can be done selectively on the basis of age and country of origin. This strategy could lead to a more economic use of the vaccine and clinic resources.

Should adolescents be vaccinated against hepatitis A: the Hong Kong experience

Hong Kong is a well developed city in the center of an endemic region for hepatitis A. The age at which hepatitis A occurs has shifted from childhood and adolescence to adults like many western countries. There is a high chance of outbreaks with the introduction of infection from neighbouring countries. Reducing the susceptibility of a population by vaccination can eliminate the diseases but updated sero-epidemiological data is needed to analyse the level of natural immunity, and identify those susceptible to infection for preventive measures. This study conducted amongst secondary school children seeks to identify those who are at risk and to obtain data on the present sero-prevalence of anti-HAV. Overall prevalence of anti-HAV in this age group was 7% increasing with age. Analysed by multiple regression model, those students living in mainland China over 3 years had odds ratio of 31.6 (95% c.i. 17.4–57.3) compared with those born in Hong Kong. Students with a father in a skilled occupation and an education level of secondary school or above, and both parents with secondary education or above, had an odds ratio of 0.22 (95% c.i. 0.07–0.7) and 0.35 (95% c.i. 0.17–0.72) associated with presence of anti-HAV, respectively. Improved socio-economic state exposes higher proportion of the population at risk. Immunisation is worthwhile to be considered for the adolescents in Hong Kong. Prevaccination screening is cost effective only for those adolescents who are most likely to have natural immunity.

Hepatitis B vaccination of personnel employed in Victorian hospitals: are those at risk adequately protected?

To examine the policies and practices in hospitals within the state of Victoria, Australia, with respect to vaccination of staff against hepatitis B infection. A written self-administered questionnaire to be completed by the infection control officer (or designated officer for hepatitis B vaccination) within each hospital. Public (teaching and nonteaching) and private hospitals, including metropolitan and rural institutions in Victoria. A random sample of 30% of Victorian hospitals were asked to participate in the survey. Of 78 eligible institutions, 69 (88%) completed and returned questionnaires. There was no consistent hepatitis B prevention policy in place across Victoria. Of the 69 responding hospitals, 63 (91%) offered hepatitis B vaccination to staff, and 58 (84%) of these also paid all costs of vaccination. Of the 63 hospitals offering vaccination to staff, 39 offered vaccination to all staff, 23 offered vaccination based on job title, and one offered vaccination based on anticipated exposure. In many institutions, postexposure protocols were recalled more readily than preexposure vaccination guidelines. Numerous respondents indicated a need for clear guidelines on policy and clarification on practical matters of management, such as acceptable immune levels, management of nonresponders to the primary series, and the need for, and timing of, booster doses of vaccine. Eleven (18%) of the 63 hospitals offering hepatitis B vaccination to staff undertook routine prevaccination screening, a practice not generally regarded as cost-effective in Australia. Fifty-five of these hospitals (91%) also undertook postvaccination screening. It is evident from this study that a considerable number of potentially susceptible healthcare personnel in Victorian hospitals remain unprotected against hepatitis B infection. A more reliable and consistent approach to preexposure hepatitis B vaccination is recommended.

Is prevaccination screening for hepatitis B among sexually active adolescents cost-effective?

Is prevaccination screening for hepatitis B among sexually active adolescents cost-effective?