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Commonly asked questions about hepatitis B vaccination.

In recent years I have spent an increasing amount of time responding to questions about hepatitis B vaccination. Inquiries come from employees at my own laboratory, health care workers at other local hospitals and clinics, and our physician clients. Typically, they want to know whether primary hepatitis B vaccination is worthwhile.

Among the question asked by those considering initial vaccination, four predominate: How great is my risk of contracting hepatitis B in the workplace? How serious is the disease? Is the vaccine safe? (Hardly anyone asks whether it is effective.) Should I undergo testing before vaccination to determine whether I am immune, or after receiving the vaccine to be sure it "took"? In addition, people have been calling me to ask if they should receive a booster dose five or more years after initial vaccination.

What sparked all this interest was a mandate by the Occupational Safety and Health Administration. OSHA decreed that employers must provide the vaccination free of charge to any employee at risk for exposure to blood potentially infected with hepatitis B virus (HBV). Previously, when employees were expected to pay all or some of the cost for vaccination themselves--$100 or more--some found the cost:benefit ratio unfavorable and declined to participate. Now that barrier is down.

In this article I will respond to the questions noted above. Many of these observations reflect my personal opinions. Currently there is no consensus on this complex subject.

* Work threat. The question I am asked most by laboratories is "Will I get hepatitis B at work?" The beginning of the answer is that all risks are relative. Perception of risk may weigh more heavily in our decisions than facts, if known, about the risk itself.

Many highly publicized alleged health risks are hyped to some extent. Lobbyists, legislators, regulators, citizens' groups, attorneys, and advertising firms have built an industry devoted to minimizing or exaggerating certain risks in contrasst with others. Included in this category are diagnostic x-rays, high-voltage electric power lines, Alar on apples, formaldehyde, breast implants--and hepatitis B in the health care workplace.

No one can care equally about all potential dangers. A seat belt activist may not give a second thought to smoking a pack or two of cigarettes a day. Some people may lose sleep over their cholesterol counts but remain unperturbed about the presence of Alar on apples, while others storm Congress, demanding that Alar be removed from the market.

It is incontrovertible that health care personnel can acquire hepatitis B in the workplace via needlestick or mucosal contamination, but this risk must be put in perspective. HBV transmission is now far more prevalent outside the medical environment than inside it. Thus the real question is not whether health care workers should be vaccinated but whether universal vaccination should be mandated.

Last year Miriam Alter and co-authors reported that from 1982 through 1988, three risk factors accounted for more than half of all hepatitis B cases in their sentinel county surveillance study: male homosexual activity, parenteral drug use, and heterosexual contact with infected or multiple sex partners. (1) In the study segment from 1982 to 1985, health care workers "with frequent blood contact" accounted for 4% of all cases of hepatitis B. From 1986 to 1988, the percentage of persons with hepatitis B working in a health care setting fell to just 1% of the total study group. No doubt both vaccination and use of universal precautions played a role in this decrease.

Alter's group reported that 40% of at-risk health care workers had been vaccinated. Beyond this, of the hepatitis B cases identified in the 1986-88 segment of the study, 99%--among women, 100%--were unrelated to the provision of health care.

Furthermore, Alter's data reflect reported clinical cases of hepatitis, whereas most cases of hepatitis B are subclinical. Some female health care workers would probably have been identified as carriers of HBV if the survey had been serologic rather than epidemiologic.

* Severity of disease. Although hepatitis B is usually not a serious illness among adults, it can be. Most adult cases are subclinical and end in complete recovery; in fact, only 25% of all cases have clinical signs and symptoms. It has been estimated that 100 to 200 deaths are caused by the rare cases of acute fulminant hepatitis B in the United States each year.

More common is chronic active hepatitis, with its long-term debilitating sequelae. The risk of acquiring this illness in a health care setting, however, is generally perceived to be greater than it actually is.

Chronic hepatitis B develops in 70% to 90% of infants who are born to HBsAg-positive mothers and who are not given prophylaxis at birth. Among children aged 1 to 5 years who contract hepatitis B, 25% become chronic carriers of hepatitis. In contrast, only 6% to 10% of adults with hepatitis B become chronic carriers. For this unfortunate minority, cirrhosis, liver cancer, or both are likely to develop.

The high risk of chronic carriage of hepatitis B following congenital infection underscores the need to reevaluate our current focus. Mandating free vaccination for health care workers without at least encouraging women of childbearing age to receive vaccination serves the cause of public health inconsistently and perhaps thoughtlessly.

* Safety. Two vaccines for hepatitis B have proved remarkably safe. Merck Sharp & Dohme's Heptavax was the first vaccine to be introduced. It was developed from pooled plasma of HBsAg-positive individuals, some of whom were at risk for HIV. Studies of large numbers of vaccine recipients, however, showed no evidence of transmission of HIV. [2] Among the first 200,000 persons vaccinated, the Centers for Disease Control reported 118 illnesses of various types, of which 62 may have been vaccine related. Six were deemed serious. [3]

Although the original vaccine remains commercially available, most vaccination is now given using a recombinant antigen grown in a culture of baker's yeast. Licensed by the FDA in July 1986, this newer vaccine, Recombivax (also from MSD) has been proved safe. Only pregnant women and individuals with yeast sensitivity are advised against using it.

* Effectiveness. Although I am seldom asked about the efficacy of hepatitis B vaccination, it is worth observing that the vaccine is highly effective. A study by Szmuness et al revealed that 96% of hemodialysis employees developed anti-HBs after receiving the standard series of three injections. [4] Older vaccine recipients and those with chronic illness responded less well.

* Bottom line. Is primary vaccination a good idea? According to the cost: benefit ratio to health care workers, yes, since they must no longer incur any expense. The risk: benefit ratio also favors vaccination.

Since it is impossible to determine whether the decline of hepatitis B among health care personnel has resulted from vaccination, increased use of universal precautions, or both, it is prudent to opt for vaccination--which is equally worthwhile for those who do not work in health care settings. Nevertheless, Alter's data make it hard to justify twisting the arms of health professionals who say, "No, thanks. I'll pass."

* Testing before and after. People often wonder whether to be tested before vaccination for existing immunity to HBV or after vaccination to determine whether inoculation was successful. The answer to the first part of that quandary depends on the expected prevalence of serologic markers in the target population, the cost of screening, and the cost of the vaccine. In most cases, although screening is cost-effective among high-prevalence groups overall, each individual must be evaluated separately. [5]

Overall guidelines for a group do not necessarily apply equally to everyone in the group. Since more than 90% of vaccinees produce anti-HBs, routine post-vaccination screening is appropriate only for those few persons in whom suboptimal response is likely and whose medical management or employment duties hinge upon knowledge of their immune status. [6]

Whether people should be retested five or more years after initial vaccination to determine the need for a booster is not well established. Although levels of anti-HBs decline over time after vaccination, immunity apparently can outlast demonstrable antibody.

In a study published in 1986, 773 homosexual men engaging in high-risk activity for acquiring hepatitis B were monitored for five years after primary vaccination. Fifteen percent lost antibody entirely; an additional 27% had declines of less than 10 SRU (comparable to 10 mIU of anti-HBs). During this time, eight developed the disease. Six subjects had had either no antibody response or a poor one. Only two cases of clinically significant hepatitis B occurred, one in a man whose initial anti-HBs response to the vaccine was suboptimal and the other in a man whose initial antibody response was brisk but whose antibody level was lower than 10 SRU 18 months later. [7] Other studies conducted on individuals who were not at high risk for HBV infection have yielded similar results.

* Boosters. While the 1986 study and others suggest that cell-mediated immunity outlasts the presence of demonstrable antibody, the issue of revaccination is complicated by the occasional person who develops hepatitis B despite the presence of antibody levels greater than 10 mIU. Presumably these cases result from infection with subtype "ad" in individuals whose antibody was predominantly to subtype anti-"ay," or vice versa. [8]

No current data are available upon which to establish a rational police for revaccination. I recommend that previously vaccinated individuals be offered one booster dose five years after primary vaccination. Before administering the booster, we offer to obtain quantitative anti-HBs levels (in SRU). I try to discourage our employees from requesting a test for those levels after vaccination. If they insist, we perform this test as well.

Many issues related to hepatitis B are unresolved. Still to be determined are the value of a low-dose booster vaccine, possibly intradermal; monitoring of quantitative anti-HBs at five or more years to assess the need for revaccination; and an automatic booster at five or more years without benefit of pre- or post-testing. Any reasonable policy is currently acceptable as long as it is understood by all employees to whom it applies.

[1] Alter, M.J.; Hadler, S.C.; Margolis, H.S.; et al. The chancing epidemiology of hepatitis B in the United States. JAMA 263:1218, 1990.

[2] Centers for Disease Control. Hepatitis B vaccine: Evidence confirming lack of AIDS transmission. MMWR 33(49): 685-687, 1984.

[3] Centers for Disease Control. The safety of hepatitis B virus vaccine. MMWR 32(10): 134-136, 1983.

[4] Szmuness, W.; Stevens, C.; Harley, E.J.; et al. Hepatitis B vaccine in medical staff of hemodialysis units. N. Engl. J. Med. 307: 1481-1486, 1982.

[5] Centers for Disease Control. Inactivated hepatitis B virus vaccine: Recommendation of the Immunization Practices Advisory Committee (ACIP). MMWR 31(24): 317-328, 1982.

[6] Centers for Disease Control. Update on hepatitis B prevention. MMWR 36(23): 353-366, 1987.

[7] Hadler, S.C.; Francis, D.P.; Maynard, J.E.; et al. Long-term immunogenicity of hepatitis B vaccine in homosexual men. N. Engl. J. Med. 315: 209-214, 1986.

[8] Swenson, P.D.; Escobar, M.R.; Sobieski, T.J.; et al. Failure of pre-existing hepatitis B surface antibody to prevent subsequent acute hepatitis B (abstract). Am. J. Clin. Pathol. 78: 264, 1982.
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Author:Soloway, Henry B.
Publication:Medical Laboratory Observer
Date:Nov 1, 1991
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