Questions & Answers

Questions & Answers

Questions & Answ-ers What is the difference between the Merck Sharp and Dohme hepatitis vaccine and hepatitis vaccines produced in other countries? Dr...

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Questions & Answ-ers What is the difference between the Merck Sharp and Dohme hepatitis vaccine and hepatitis vaccines produced in other countries? Dr. McLea n • Of hepatitis B vaccines made in other countries, the one made by the Pasteur Institute has been available the longest. All hepatitis B vaccines presently available are made from the plasma of hepatitis B carriers. The Pasteur vaccine is purified by physical means and is then treated with formaldehyde only. It does not go through enzyme digestion with pepsin or treatment with 8 mol urea. There was also a vaccine for a short time in Holland made by the Dutch Red Cross . It was not well purified. The inactivation process involved two heat treatments: 101 C for 90 seconds and 60 C for 10 hours. It also had a single-step inactivation process . The vaccine recently available through the Korean Green Cross is much like the Merck vaccine. The two-step inactivation process involves pepsin and form a ld eh yde. The World Health Organization published recommendations on h epatitis B vaccine products some months ago. They stated that any hepatitis vaccine that is m ade from human plasma should be purified and incorporate at least two different types of viral inactivation in its preparation. Can a hepatitis B carrier be treated with massive doses of hepatitis B immune globulin to reduce the antigen level so that the patient isn't quite as infectious while being treated? Dr. Cottone • Studies have been performed that indicate that such treatment is ineffective. If you are treating a carrier, the best protection is to have antibodies yourself. There is no real treatment for the carrier state at this time.

mitting hepatitis to patients, may possibly need informed consent from patients, and is wearing gloves and a mask at all times. However, man y times, the carrier den tist is not willing to accept that kind of a risk. So , I knovv few who have actually gone back into practice, reall y only two.

If a person either has acquired immunity or receives the vaccine, doesn't it seem theoretically possible that, because of the exposure to hepatitis in the dental profession, we wouldn't need a booster? We will simply be exposed so routinely that these exposures will boost our immune level. And secondarily, do you recommend any kind of annual routine antibody testing for the practitioner? Dr. Cotton e • The first part of the question is theoreti cally true as subsequent exposures to HBV sh ould initiate an anamnestic or secondary re sponse and in crease the antibody titer. Dr. McLean m entioned that this occurred earlier in the male homosexual studies in Ne w York. Three people who were exposed to HBV after vaccination developed anamnestic responses. Dr. Mitch ell • We have recommended routine testing after receipt of the vaccin e . As Dr. McLean presented today, studies of up to 7 to 8 years indicate that a ntibody titer is p ersisting, but confirmatory testing is recommended. One of the ways this can be accomplished is through participation in the ADA h ealth screening program at annual sessions. Dr. Cotton e • However, routine yearl y antibody testin g is not necessary once antibodies have developed. Probably one test 5 years after receiving the vaccine w ill tell you if a booster dose is needed.

What follow-up does the ADA provide for the dentist who develops the carrier state? Dr. Mitchell • That is a difficult question to answer because the only service we can provide is to keep in touch and en courage these people to continue to comm unicate with us . We really don't have anything positive to offer, except a little sympathy. We have advised some of the carriers who are not e antigen positive to take a close look at how they feel about going back into practice using appropriate barrier techniques as outlined by the CDC . In some cases, the carrier dentist can go back into practice when there is clear eviden ce that h e or she is not trans-

We routinely spatter contaminated material onto our clothing in the dental office and then take the clothing home and wash them in routine detergents. I s that procedure enough to remove HBV and not cont aminate the washing machine? · Dr. Crawford • The CDC has stated that washing is one of the best ways to remove HBV from surfaces. If I were really concerned about some clothing, I would wash it twice by itself. Adding chlorine bleach is also h elpful if it will not damage the clothing. HEPATITIS SYMPOSIUM • 647

If newborn infants of e antigen positive carrier mothers have a 90% infection rate and a subsequent 85% to 90% carrier rate, why is it that they are capable of responding to the vaccine but incapable of responding to the virus itself?

Dr. Kane • No one understands the exact mechanism, but many immunosuppressed patients show the same kind of pattern of differential effect of responding to the virus versus the vaccine. For example, 90% of immunosuppressed children with Down's syndrome will respond with antibodies to the vaccine, yet 40% to 60% of them will become carriers if infected with the virus. Most dialysis patients and patients who are receiving immunosuppressant drugs for cancer therapy can respond to the vaccine, although not as well as those with normal immune systems. Infants act like immunosuppressed Down's Syndrome patients or patients on immunosuppressant drugs. They are capable of an antibody response to the vaccine, but a virus infection often overwhelms their immune system.

Do you think the present policy that allows health care professionals who are hepatitis B carriers to continue their practice will remain the same or become more stringent? Dr. Kane • We think there are about 3,000 dental personnel in the United States who are HBV carriers and probably tens of thousands of m edical personnel who are carriers. These people are valuable assets to their communities and we believe that transmission from them to patients is rare. We don't think that it is reasona ble to tell 3,000 dental personnel to stop practicing dentistry because somebody might sue them someday. Until we have good evidence that HBV transmission is much more frequent than we think it is, I doubt that this policy is going to change in the near future.

Do you think the policy of informed consent from the patients of HBV carrier dentists will remain the same? At present, the policy from both the CDC and the ADA appears to be that (1) if you are a carrier and have been found to be transmitting disease, it is necessary to get informed consent from your patients, and (2) if you're a carrier and have not been transmitting disease, you don't need informed consent. Dr. Kane • I think that if a carrier de ntist who is not transmitting disease was required to obtain informed consent from all patients , it could significantly hurt his or her practice. Again, until there is evidence that transmission from these individuals is other than a rare event, I don't think the policy will change. Mrs. Baker • The law is muc h simpler tha n the facts. If it's a patient care issue and there is a threat to patients, then you must take steps to prevent that threat. This may mean not being able to practice or restricting the types of procedures that you can perform . If there's no threat to patients or the threat is minimal or n egligible , there is no problem. It is alright to require informed consent from patients in a practice of someone who h as transmitted disease in the past, but the consent still may not hold up in court. It is not the usual informed consent situation such as when a patient is hospitalized for elective surgery and h as tJ:e 648 • JADA, Vol. 110, April 1985

risks and benefits of the operation explained. I think the patient who contracts h e p a titis B from a carrier dentist, even though he or she gave informed consent, can still potentially challenge the validity of the consent form. Dr. Mitchell • The American Dental Association does not believe it is necessary for a carrier dentist to have informed consent from patients. We believe that the literature clearly shows the rarity of the occurrence of transmission from the dental professional to the patient , and that there are standards of practice-standards of carethat can be taken to prevent transmission. What would you recommend to the dental school administrator who discovers that he or she has an e antigen positive HBV carrier student or faculty member who may or may not be transmitting disease to the transient dental school patient population? Mrs. Baker • In response to your example, the first step, if that student has patient contact, is to comply with the state re porting requirement if y our state has one. The state health department may then have a protocol for you to follow. If you do not have a state reporting requirement , what do you do? You need to carefully balance several items. The first item is the possibility of transmission of hepatitis to patients, so the precautions recommended by the CDC should be followed. If the student has not transmitted disease at this time to any patient, informed consent would probably not be required from patients , but proper barrier and aseptic techniques should be strictly followed. On the other hand, you need to be careful not to unduly discriminate against the carrier student or faculty member because there is evidence that he or she can practice in a safe manner w ithout infecting patients. You must balance the possibility of transmission during patient care (doing everything y ou can to protect against possible transmission) with undue discrim ination against the carrier. I haven't taken the hepatitis B vaccine because I have been either pregnant or nursing in the last 18 months. Is pregnancy or nursing a valid contraindication to vaccination? Dr. McLean • Not that we've seen, not that we know of, and not that we would ever theoretically expect. T h e vaccine antigen is only the surface antigen. It is not the entire virus. Theoretically, we would not expect any problem in a woman who became pregnant, either to the woman or to the baby . However, systematic trials in pregnant women have not been performed and therefore the package circular reflects this and states that the vaccine should be given to a pregnant woman only if clearly n eeded. That is , only if she is in a high-risk category, she is going to stay in that category, and she has bee n informed of the lack of studies and also the risk of getting hepatitis B if she doesn't take the vaccine. As a practitioner and an employer, if I know that an employee is at great risk of hepatitis B and yet I do not require him or her to have the immunization, am I still liable? Mrs. Baker • If you are a dental employer and you offer the vaccine to employees and they d ecline the vaccine but

contract hepatitis B, you are still liable under worker's compensation. You then have to pay t he worker's compensation claim for their injuries , for their d am ages in accordance with that schedule. So , yes ; you are still liable for their injury if they don't take the vaccine. However , what you have done is eliminate the other negligence liability because it was no lon ger your decision or your fai lure to offer the vaccine that was the cause of their injury; it was their own decision. You were not the cau se of their disease state. You are still liable under worker's compensation, but you are not li able unde r n egligence.

In a modern dental practice, the dentist moves back and forth from patient to patient, and from chair to chair. Is it necessary to change gloves every time the dentist moves?

Dr. Crawford • We h ave cultured and spot-tested gloves after washing them while practicing d entistry and , if th ey are intact, we fou nd an essentially sterile glove. However, I would rather have my dentist wear n ew gloves w h en treating m e, espe cia lly if I am paying $40 or $80 an hour. I feel I am worth 10 or 20¢ for new gloves . I think the outside limit the Public H ealth Service h as set is 1 h our for a set of gloves . Then the gloves should be discarded, w hatever you are doing. Dr. Cottone • Mor e information should be availa ble on this subject in the n ear future .

What might happen if I discover that I have hepatitis B and can identify the patient who infected me? Could I possibly litigate against the patient and win?

Mrs. Baker • The patient does not owe a duty to the dentist to disclose his or h er history . There may be a moral or an ethical duty, but there is no legal duty of the patient to d isclose h is o r her his tory. You probably would have no cau se of action against the patient.

What is the shelf-life of the vaccine in the refrigerator?

Dr. McLean • T h e shelf-life is 3 years when the vaccine is refrigerated. Dr. Crawford • freezing .

Use caution to protect the vaccin e from

Suniniary Dr. Mitchell • W h at I would like you to d ecide today is that you will take some time and really take a c lose look at how you practice. Not just the chemical agents that you use , not just what you use as a sterilizer, but look at e very step in your office procedure. Look at your infection control procedures and see if they are adequ ate-not just for hepatitis B, but for any known viral agent tha t might en te r your office. I h ope we have increased your aware ness that you are an employer, and that you h ave certain responsibilities to your employees that you might not have thought about before in terms of the medical or the legal issues . Dr. Crawford • In a small office w h ere you are th e boss , or in a sm all grou p p ractice, it s h ou ldn 't be too difficult to set some goals and standards. It 's a "num bers" game you 're playing. The more microorganis m s and viruses your office is contami n ated w ith, the more ch ance you have of becoming infected a nd infecting someone else. Go back a nd organize a small committee ; set aside some time every week or every 2 weeks; draw up a short outline of steps you can take to improve your office infection control

procedures; inclu d e long-range p la nning for diffi cu lt or expensive changes. The more relaxed PHS guidelines for dentist carriers w ho use adequate barrier protection are appropriate. I agree that th is person need not obtain signe d con sent form s from each p a tient. I cannot im agine a carrier-dentist who wears gloves be ing injured en ough to bleed through the glove to expose a patient under treatment without the dentist being aware of the occurrence and taking steps to protect the p atient with passive immunoprophylaxis . Dentists who do not know they are carriers can n ever be aware of exposing a patien t and would also be less inclined to routinely use ad equate barrier protection. Dr. Cottone • No one expects y ou to ch ange all y our office procedures over night. Do the best you ca n , but d on't put these issues on the " back burner." You h ave a n umber of choices: pretesting, vaccination, p ost-exposure pr ophylaxis, and post-immunization testing. All it ta kes is one unpro tected exposure to be infected or to start a chain of events you m a y not want in your p ractice.