Since a vaccine for active immunization became available in 1992, hepatitis A virus (HAV) infection has become a preventable disease. In contrast to some other parts of the world, we do not have a routine vaccination schedule for HAV for infants in the Netherlands; vaccination is recommended for travelers aged ≥1 year to hepatitis A endemic countries, for persons who are at increased risk of infection within the Netherlands, and for people with liver diseases like chronic hepatitis B or C infection. Hypersensitivity to any component of the vaccine or severe febrile illness are contra-indications. Immune responses to hepatitis A vaccination in healthy people are excellent,[5-9] but serology is recommended when a reduced response to vaccination is expected due to an altered form of administration or immunodeficiency caused by disease or therapy.
Since increasing numbers of travelers using immunosuppressive medication visit countries for which vaccination is recommended, the need for reliable information on immunogenicity of vaccines in this group grows. The purpose of this study is to explore the effectiveness of hepatitis A vaccination, measured as seroprotection rate, in persons who are treated with different types of immunosuppressive medication.
Subjects and Methods
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- Subjects and Methods
- Declaration of Interests
In this retrospective study, databases from the years 2005 up to 2012 of five municipal public health travel clinics and one hospital-based travel clinic were screened for records including hepatitis A serology. Reasons for antibody testing were evaluated. Records of persons vaccinated intramuscularly with monovalent hepatitis A vaccine and treated with systemic corticosteroids (prednisolone equivalent of >10 mg daily for at least 2 weeks or >700 mg consecutive), methotrexate, azathioprine (or 6-mercaptopurine), other cytostatics, anti-TNF alpha, other systemic immunomodulating drugs or a combination of these drugs were further evaluated. In case of combination therapy which included anti-TNF alpha this was considered the most potent drug; combined therapy of corticosteroids with methotrexate or azathioprine was counted for either methotrexate or azathioprine. Subject characteristics, total number of hepatitis A vaccines received, date(s) of vaccination, and the date of antibody testing were recorded. Except for persons using immunosuppressive medication, all persons who according to Dutch national guidelines require hepatitis A serology after vaccination (total body radiation therapy, congenital, or acquired immunodeficiency) were excluded. Also HIV-seropositive persons, subjects with a primary hepatitis A vaccination before the start of immunosuppressive therapy and persons with severely impaired humoral immunity were excluded. Subjects were either counted for in the single vaccination group or complete vaccination series. Labs determine qualitative or quantitative antibody titers, but always provide collaborating travel clinics with qualitative results analyzed by one of the following systems: AxSYMMicroparticle Enzyme Immunoassay (MEIA; Abbott, Chicago, IL, USA), Architect Chemiluminescence Microparticle Immuno Assay (CMIA; Abbott), ADVIA Centaur Chemiluminescent Immunoassay (Siemens, Erlangen, Germany), and VIDAS Enzyme Linked Fluorescent Immunoassay (BioMeriéux, Marcy l'Etoile, France).
To evaluate the effect of anti-TNF alpha as a group, subjects using these drugs were combined and compared with subjects using classical anti-rheumatics and a group using other immunosuppressive drugs (Table 1). To evaluate whether age is of influence on response to vaccination, three age groups were formed, young (<40 years), middle aged (40–60 years), and elderly (≥60 years). Associations between protective titers after vaccination and other variables were examined using the two-sided χ2 test. A multivariate logistic regression model was used to adjust for age group, gender, and medication group. All calculations were performed using spss version 20.0.
Table 1. Baseline characteristics
| ||Anti-TNF groupa||Classic anti-rheumaticsb||Other immunosuppressivesc|| |
|Charcteristics||n = 31||n = 123||n = 19||p-Value|
|Age, median (range), years||50 (22–76)||49 (19–78)||51 (20–61)||0.644e|
|Single vaccination (%)||71||64||79||0.391d|
For this non-interventional retrospective study no ethics committee approval was required.
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- Subjects and Methods
- Declaration of Interests
Between January 2005 and June 2012, in total 740 records of hepatitis A serology were documented. Reasons for antibody testing before or after vaccination were subcutaneous vaccination (16%), possible pre-vaccination exposure to HAV (46%), immunosuppressive medication in combination with HAV vaccination (23%), and others including serology after hepatitis A and B bivalent vaccine, prior vaccination status, and unclear course of events (15%). One subject was treated with rituximab and therefore excluded. For the 173 subjects that met the inclusion criteria (62% female, median age 50 years, range 19–78 years) methotrexate was the drug most frequently taken (33%) followed by azathioprine (23%), anti-TNF alpha (18%), corticosteroids (15%), cytostatics (5%), and others (6%). Sixty-seven percent of the individuals was tested after a single vaccination and 33% after two doses with an average interval of 73 weeks (range 19–430 weeks). The average interval between the last vaccination and serology was 16 weeks with a range of 2 to 394 weeks. No significant baseline differences in age, gender, and number of vaccinations were observed between the three drugs groups (Table 1).
Antibody titers taken less than 4 weeks after primary vaccination resulted in seroprotection rates of 50%. When samples were taken after 4 weeks or more, seroprotection rates increased to 64%, although this difference was not significant (p = 0.146). The overall seroprotection rate after a single vaccination was 60%. After the second vaccination seroprotection rates for the whole group reached 95%. Of the subjects using anti-TNF alpha, 46 and 79% were protected after a first and second vaccination, respectively. For subjects using classical anti-rheumatic drugs seroprotection rates were 62 and 98%, and in the group using other immunosuppressive drugs seroprotection rates were 67 and 100% (Figure 1). The subject's age is not of significant influence on seroprotection rates. Seroprotection rates in the youngest age group were 57 and 95% after one and two vaccinations, respectively. For the second age group rates were 56 and 92%, and for the oldest group 68 and 100% (Figure 1).
Figure 1. Seroprotection rates after a single vaccination and after a series of two vaccinations. Anti-TNF alpha: anti-tumor necrosis factor α therapy. Classical anti-rheumatics: corticosteroids, methotrexate, and azathioprine. Other: immunosuppressive medication, not anti-TNF alpha, or classical anti-rheumatics. *p-Value from two-sided Pearson's χ2 test between immunosuppressive medication used after two vaccinations; 0.045. p-Value for age groups after two vaccinations; 0.555.
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The frequency of anti-TNF alpha usage per age group was higher for the younger than for the older groups: 26% (9/35) for the youngest, 20% (10/50) for the middle group, and 10% (3/31) for the oldest group after one vaccination (p = 0.245), and 20% (4/20), 13% (3/24), and 15% (2/13) after a complete vaccination series (p = 0.793). Multivariate logistic regression analysis with age group, gender, number of vaccinations, and anti-TNF alpha versus no anti-TNF alpha usage as independent variables, showed that only the use of anti-TNF alpha versus other immunosuppressives [odds ratio (OR) = 0.40, 95% confidence interval (CI): 0.16–0.99] and a second vaccination given or not (OR = 13.01, 95% CI: 3.76–45.04) were of significant influence on seroprotection rates.
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- Subjects and Methods
- Declaration of Interests
For a number of disorders the effect on the immune response after hepatitis A vaccination has been studied before; seroconversion rates in HIV-seropositive persons are significantly lower than in HIV-negative men, with the CD4 count being related to response rate.[11-13] As far as we know, this is the first study to evaluate the effect of hepatitis A vaccination in a population using immunosuppressive drugs. The monoclonal antibody rituximab, aimed against B-lymphocytes and thus influencing humoral response is known to result in a reduced antibody response after influenza vaccination.[14-17] For other immunosuppressive drugs only some data on response to influenza vaccination are available. In patients treated with anti-TNF alpha, a good serological response was found, equal to, or slightly lower than in control groups.[18-20] Vaccination while using methotrexate induces satisfactory humoral responses,[19, 21] as well as vaccination under corticosteroid treatment[19, 22] or azathioprine treatment.
Our findings indicate that satisfactory anti-HAV titers after vaccination are also acquired despite the use of immunosuppressive drugs. Seroprotection rates after a complete vaccination scheme depended on the drug used. Seventy-eight percent was protected when anti-TNF alpha was used and 98% when classical anti-rheumatics were used. Since many travelers visit the travel clinic shortly before departure the response after a single vaccination is also relevant. As expected, seroprotection rates are lower than after a complete series, 60% versus 95% (p < 0.05) for the whole group, 67% versus 98% (p < 0.05) for the classical anti-rheumatics group, 46% versus 78% (p > 0.05) for the anti-TNF alpha group, and 67% versus 100% (p > 0.05) in the group using other immunosuppressives. In only 50% of the subjects a protective antibody titer was found within 4 weeks after a single vaccination, after 4 weeks this number rose to 64% (p > 0.05). These figures suggest that last-minute vaccination is not safe when travelers use immunosuppressive medication. Although passive immunization has disadvantages, including a very low risk for blood borne conditions, higher costs in repeated exposure and a maximum protection of 13 weeks, it protects effectively against clinical symptoms of hepatitis A infection and is therefore recommended in addition to the first dose of vaccine for the last-minute immunosuppressed traveler in some countries. In other countries, like Belgium and France, immunoglobulins are not registered for pre-exposure HAV immunization.
One might expect to see lower seroprotection rates after a single vaccination for the older age group, eg, based on a slower developing immune response. In our study, seroprotection rates after one or two vaccinations did not differ significantly between the three age groups. Multivariate logistic regression indicates that the less frequent use of anti-TNF alpha in the older group does not explain the relatively high seroprotection rate in this group. Relatively high seroprotection rates might be explained by a bigger proportion of that group having naturally acquired antibodies against hepatitis A. Since we do not have pre-vaccination titers, and due to the lack of power of this study, no firm conclusions can be drawn on seroconversion rates related to age.
A retrospective study like this always has its limitations. We know that immunogenicity in immunocompetent subjects is excellent. Clinical studies in this group demonstrate seroconversion rates of 79% on day 13, 86.3% on day 15, 95.2% on day 17, and 100% on day 19 after a single dose Havrix 1440 (GlaxoSmithKline UK, Middlesex, UK). In our study we did not have a pre-vaccination antibody titer, so no comment on immunogenicity of the vaccination can be made. Only the percentage of persons protected after vaccination can be given. In travel health care this is not a huge problem because the aim is a protected traveler.
Further studies are needed to evaluate the best method to protect the immunosuppressed traveler. In HIV-infected persons an alternative three dose scheme induced a significantly higher antibody titer and a non-significantly higher seroconversion rate compared to the standard two dose scheme. This vaccine scheme might also be useful in travelers using immunosuppressive medication and attending a travel clinic well before departure, but to our knowledge no studies have been conducted evaluating this scheme in this group.
While we have studied the seroprotection rate after hepatitis A vaccine we cannot conclude with certainty that in these patients insufficient antibody titers correspond with a lack of clinical protection. Documenting vaccine failures in immunocompromised travelers would bolster our results. On the basis of this study we can formulate the following advice for the professional in travel health care:
- Try to catch the (potential) traveler before he is taking the immunosuppressive drugs. Identifying the potential traveler is the most difficult part, but there are possibilities to do so. In our hospital for example, specialists prescribing immunosuppressive medication are trained and reminded by protocol to advise patients with traveling plans to visit a travel clinic.
- For the (potential) traveler already using immunosuppressive medication: for now offer a vaccination series with, if possible, post-vaccination serology. Protection rates after one vaccination are so low that we cannot assure the immunocompromised travelers that they will be protected during travel without serology testing. If more data become available post-vaccination titer might not be necessary for subjects using certain immunosuppressive drugs, eg, methotrexate, azathioprine, or corticosteroids.
- For the last-minute traveler already using immunosuppressive medication: give active vaccination together with passive immunization before this specific journey. If immunoglobulins are not available, be aware that seroprotection is low after one vaccination. When there is more interest in traveling to HAV endemic areas you can complete the vaccination series and do serology afterwards, if available.
Take Home Message
To ensure protection against hepatitis A in your immunocompromised patient a complete vaccination series is recommended before traveling. Alternatively, consider giving the first dose of vaccine with immunoglobulins in immunocompromised patients traveling last-minute to endemic areas.