Concerns regarding hepatitis B vaccination and post-vaccination test among Brazilian dentists

Hepatitis B virus (HBV) is the major cause of acute and chronic liver disease, cirrhosis and hepatocellular carcinoma worldwide and has long been recognized as an occupational hazard among dentists [1‐6]. A third of the world population (two billion people) has evidence of hepatitis exposure and an estimated 400 million are actively infected [3, 7]. HBV is one of the major diseases of mankind and is a serious global public health problem [8, 9]. HBV is transmitted primarily through parenteral and sexual exposure to HBsAg-positive blood or other body fluids from individuals who are chronic HBV carriers or have acute hepatitis B [2]. These chronically infected individuals are at high risk of death from cirrhosis of the liver and liver cancer, diseases that kill about one million people each year [10, 11].

As the dental profession involves the use of small, sharp instruments contaminated with blood or other fluids, there is ample opportunity for inadvertent skin wounds to the operator and staff [1, 2, 12]. Such accidents include the possibility of transmission of hepatitis B, hepatitis C and human immunodeficiency virus (HIV) [13]. To decrease the risk of HBV infection, it is recommended that dental personnel receive immunization against HBV and use individual protective equipment, such as gloves, to prevent blood-borne infection during dental procedures [1, 11].

The hepatitis B vaccine has been available since 1982 and, since 1990, has been recommended for healthcare workers whose activities frequently expose them to blood [7, 10, 11, 14]. However, 5 to 10% of normal subjects do not produce the anti-hepatitis B surface antibody (anti-HBs) after receiving a standard course of HBV vaccine [7, 15, 16]. Thus, post-vaccination testing one to three months following the third dose of vaccine is recommended for healthcare workers who have contact with blood [7]. Previous studies carried out in other countries have revealed different proportions of self-reported vaccination, ranging from 40.3% to 97.0% [17‐23]. The proportion of dentists who have had their antibody titer evaluated ranges from 36.5% to 47.9% [20, 21]. In Brazil, one study found that only 73.1% of dentists had been submitted to the three doses of the vaccine [24].

There is little information on factors associated to adherence to the vaccination and the evaluation of immunization status regarding hepatitis B among dentists. The aim of the present study was to examine factors associated to the self-reporting of hepatitis B vaccination and immunization status among dentists working in the city of Belo Horizonte, Brazil.

This is a cross-sectional study nested in a larger study assessing factors associated to the seroprevalence of hepatitis C among dentists in the city of Belo Horizonte, Brazil. The dentists were first contacted, enrolled and invited to take part in the study in November 2004, when all dentists registered at the Minas Gerais Dental Council were required to elect the administrative board of the council. Belo Horizonte is the capital of the state of Minas Gerais and is an industrialized city with about 2.4 million inhabitants. The sample size was calculated to give a 95% confidence interval, 0.75% precision level [25] and using a 3% prevalence of hepatitis C [10]. The inclusion criteria were dentists living and working in the city of Belo Horizonte and registered at the Minas Gerais Dental Council. This group consists of a finite population of 2766 dentists. The minimal sample size to satisfy the requirements was estimated as 1156 dentists. Taking into account the possibility of losses, a correction factor of 1.2 was adopted, totalling an expected sample size of 1387 dentists. These dentists scheduled a visit at the clinical analysis laboratory of the Medical School of the Federal University of Minas Gerais. A total sample of 1302 dentists (response rate = 93.9%) answered the questionnaire between December 2004 and June 2006. The sampling strategy is detailed in a previous article [26]. All participants signed a term of informed consent and data were collected on demographic, behavioural and occupational exposure aspects.

Among the total number of dentists surveyed, 87.1% (n = 1134) answered the question on hepatitis B vaccination and 74.8% (n = 974) answered the question on immunization for hepatitis B. Among the study sample (n = 1302), 73.9% reported having received the three doses of the vaccine. There was an association between vaccination against hepatitis B and gender (p = 0.003), use of IPE (p = 0.001), blood transfusion (p = 0.006) and combined factors (p = 0.026) in the univariate analysis (Table 1). The multivariate analysis revealed that women had a 1.06-fold (95%CI: 1.02-1.10) greater frequency of vaccination against hepatitis B than men. Dentists who reported the use of IPE had a 1.05-fold (95%CI: 1.01-1.09) greater prevalence of vaccination. Dentists who reported having received no blood transfusions had a 1.10-fold (95%CI: 1.01-1.21) greater prevalence of vaccination. Dentists reported having no combined risk factors had a 1.08-fold (95%CI: 1.02-1.15) greater prevalence of vaccination (Table 2).

When asked whether they knew their immunization status or had performed a post-vaccination test, 14.8% of the total sample reported having taken the test. Immunization status was associated with work experience (p = 0.003), the use of IPE (p = 0.003), dental care for patients with hepatitis (p = 0.011), the custom of asking patients about hepatitis during dental treatment (p = 0.001) and a family history of hepatitis (p = 0.004) (Table 3). The multivariate analysis revealed that dentists who reporting the use of IPE had a 1.03-fold (95%CI: 1.00-1.07) greater prevalence of vaccination. Dentists who asked patients about hepatitis had a 1.07-fold (95%CI: 1.04-1.11) greater prevalence of immunization. Dentists who reported a family history of hepatitis had a 1.06-fold (95%CI: 1.02-1.12) greater prevalence of immunization. Dentists with less than 10 years of experience had a 1.07-fold (95%CI: 1.02-1.12) greater prevalence of immunization when compared to dentists with more than 30 years of experience. Dentists with 10 to 20 years of experience had a 1.07-fold (95%CI: 1.02-1.13) greater prevalence of immunization when compared to dentists with more than 30 years of experience. There was no difference in the prevalence of immunization between those with 20 to 30 years of experience and those with more than 30 years of experience (Table 4).

Prevention is ultimately the most efficient and humane means toward improved health [33]. Immunization programs are highly effective, clearly protect populations and individuals at risk and are leading to the elimination of hepatitis B [34]. Viral hepatitis is preventable with effective vaccines, which have been available since 1982 and have proven safe to both adults and children [7, 10]. However, despite being safe, efficacious and cost-effective, hepatitis B vaccination remains consistently under-employed [34].

Reports from different countries reveal that some dentists do not engage in safe practices, such as the use of gloves, facemasks or protective eyeglasses. Moreover, hepatitis B virus vaccination coverage is not complete among dentists, as reported for countries such as Nigeria, Jordan, Iran and the United Kingdom [17‐23].

The results of the present study reveal that an average of 73.8% of the dentists had taken the three doses of the hepatitis B vaccine. The Brazilian Ministry of Health offers the National Viral Hepatitis Program, which has provided free vaccinations for newborn children, adolescents, those who work in the sex industry and healthcare workers since 1998. Thus, a higher number of vaccinated dentists was expected. However, this is a good coverage compared to countries that do not have government vaccination programs, such as Kenya, where only 12.8% of healthcare workers have been vaccinated for hepatitis B [23]. It is important to point out the differences between the two studies: The present study was carried out in a large city, whereas the Kenyan study was carried out in Thika, which is a typical small Kenyan district [23]. The number of vaccinated dentists in the present study was also higher than that reported for correctional healthcare workers in three American states, in which only 64% of the 411 professionals interviewed reported having received all three doses of the vaccine [35]. On the other hand, vaccination coverage among English dentists is quite higher than that reported in the present study [22].

Female dentists, dentists who use IPE and those who reported the use of illicit drugs had a greater prevalence of vaccination for hepatitis B. A study carried out in the city of Recife (Brazil) found that women adhere to infection control measures more than male dentists [36]. It is troubling that dentists who use illicit drugs and those with a history of blood transfusion have a lower proportion of adherence to the vaccination than those who do not report these factors, considering the increased risk [2]. On the other hand, it appears that the dentists who adhere more to infection control measures, such as the use of EPI, also have a higher prevalence of vaccination. This finding is similar to that reported in a study carried out in Iran [20].

Regarding vaccination status, there were no differences in relation to work experience. This may be explained by the fact that all the three dental schools in the city of Belo Horizonte offer an immunization program for their students before initiating dental practice, which explains why most of the dentists are vaccinated, especially those recently graduated. Those with a longer-standing profession may have been vaccinated during a campaign by the Dental Council of Minas Gerais in 1996, when all dentists in the state were offered free vaccinations. However, vaccination goes beyond taking vaccines; it implies a monitoring process, which is seldom considered including all vaccine series and over the lifetimes of individuals [33].

There was a very low prevalence of hepatitis B immunization. Studies carried out in Iran report that dentists take the test for the evaluation of immunization status with a frequency least 2.5-fold greater than Brazilian dentists [20, 21]. This finding underscores the need for collective actions for raising the awareness of Brazilian dentists with regard to the evaluation of immunization status for this disease.

Dentists who adequately employ IPE, those who obtain a patient history regarding hepatitis B, those with a family history of hepatitis B and those more recently graduated had a greater frequency of self-reported immunization for hepatitis B. As mentioned above, dentists with a more favourable behaviour with regard to infection control measures are more apt to adhere to an immunization evaluation. Living with the disease in the family setting may have sensitized these dentists to adhering to every prevention protocol in the professional setting. Likewise, dentist who more recently graduated may have been submitted to a different training/education process in relation to infection control measures. Further education may be appropriate in order to impress upon dental students and dentists alike the importance of knowledge on their own vaccination and immunization status.

The present study has some limitations that must be recognized. Cross-sectional studies are carried out either at a single point in time or over a short period. Thus, associations identified in cross-sectional studies should not be considered a causal relationship. However, there is a lack of studies that concomitantly assess the knowledge of dentists regarding their own hepatitis vaccination and immunization status, as we performed in the present study.

Given the huge burden of hepatitis B infection worldwide and the number of advances made in the past several decades, it is surprising that more progress in limiting the infection has not been made. Hepatitis B continues to spread in endemic areas where universal vaccination has not yet been achieved. The availability of the vaccine and its use in preventing neonatal transmission as well as the increasing use of suppressive therapies should yield greater gains in the eradication of hepatitis B in upcoming generations [3, 4]. Moreover, dentists should be better instructed with regard to the importance of compliance to the vaccination and taking the post-vaccination test in order to assist in the elimination of hepatitis B.

The prevalence of hepatitis B vaccination among Brazilian dentists was associated to gender, blood transfusion and risk behaviours. A low percentage of dentists reported having taken the post-vaccination test and few were aware of their immunization status. We strongly recommend that dentists, as a potential risk group, should know their immunization status so that those who require revaccination can obtain it.