Chris Miller, PHD
After several years of development, the CDC published its recommendations on immunization of health-care workers (HCWs) at the end of 1997. These recommendations consolidate those from the Advisory Committee of Immunizations Practices and the Hospital Infection-Control Practices Advisory Committee. The main CDC comments and recommendations (Morbidity and Mortality Weekly Report vol. 43, No. RR-18, December 26, 1997) are summarized here.
The recommendations apply to all HCWs (including all dental professionals and related students) who contact patients or infective materials from patients. Maintenance of immunity is an essential part of prevention and infection-control programs involving HCWs. It safeguards HCWs as well as protects patients from becoming infected through exposure to infected workers.
Heath-care facilities are encouraged to develop an immunization policy for HCWs. The CDC strongly recommends immunization against hepatitis B, influenza, measles, mumps, rubella, chickenpox and, in very special circumstances, tuberculosis.
While hepatitis A, meningococcal, typhoid and vaccinia vaccines are available, they are not specifically recommended for dental workers or for other HCWs unless there is special potential for exposure. Tetanus and diphtheria immunizations are recommended for all adults and the vaccine for pneumococcal pneumonia is recommended for those over age 65 or who have other increased risk of pneumonia. All vaccines have some contraindications so your personal physician should be consulted whenever considering vaccination.
Hepatitis B vaccination. CDC indicates that hepatitis B is the major infectious hazard for HCWs. Fortunately, there has been a 90 percent decrease in the number of HCWs who became infected with the hepatitis B virus (HBV) over the period 1985 to 1994. However, from 100 to 200 HCWs have died every year during the last decade from the consequences of chronic hepatitis B infection.
The OSHA bloodborne pathogens standard mandates that employers of HCWs who may be exposed to human body fluids be offered the hepatitis B vaccination series free of charge. Prevaccination screening for prior HBV infection is not indicated for HCWs. However, testing for an antibody response (immunity) one or two months after receiving the three-dose vaccination series is indicated by CDC for HCWs who continue to have contact with patients or infective material and are at ongoing risk for injuries with contaminated sharps.
Knowing if the vaccination series worked is important because a small proportion of those vaccinated do not develop immunity. Also, knowing one`s immune status against hepatitis B aids in determining an appropriate prophylaxis when a subsequent exposure does occur (after a sharps injury, for example). Such prophylaxis is part of the OSHA-mandated post-exposure medical evaluation to be provided to employees exposed to body fluids.
CDC still does not consider booster doses (those after the initial three inoculations) necessary. Studies among adults have shown that vaccine-induced immunity continues to prevent clinical hepatitis or detectable viremic HBV infection even though measurable levels of antibody in serum decline with time. Although antibody testing about one to two months after completing the HBV vaccination series is recommended as stated above, subsequent periodic testing for antibody is not recommended by CDC.
The hepatitis vaccination series is provided in three intramuscular doses. The second dosage is one month after the first one, and the last dose is administered six months after the initial dosage. CDC indicates that pregnancy should not be considered as a contraindication to vaccination. Previous anaphylactic reaction to baker`s yeast is a contraindication to vaccination because yeasts are used in the vaccine-manufacturing process.
Influenza vaccination. Influenza vaccination is especially indicated for HCWs who have contact with patients at high risk for influenza or its complications: HCWs who work in chronic-care facilities and HCWs who themselves have high-risk medical conditions or are age 65 or older. Protection against influenza involves annual intramuscular vaccination with the current vaccine. The vaccine contains three inactivated influenza viruses of the most currently prevalent types. A history of anaphylaxis to egg ingestion is a contraindication to vaccination.
Measles vaccination. This vaccination involves two subcutaneous doses one month apart of the live-virus vaccine. It is indicated for all HCWs born during or after 1957 who do not have documentation of 1.) having received two doses of the live vaccine on or after their first birthday, 2.) a history of physician-diagnosed measles 3.) Or serologic evidence of immunity.
Vaccination should be considered for all HCWs who lack proof of immunity, including those born before 1957.
Contraindications include pregnancy, immunosuppression, anaphylaxis after ingestion of gelatin or administration of neomycin and recent administration of immune globulin.
Mumps vaccination. Vaccination against mumps involves one subcutaneous dose of the live-virus vaccine with no booster. It is indicated for all HCWs who are believed to be susceptible. Adults born before 1957 can be considered immune.
Contraindications include pregnancy, immunosuppression and a history of anaphylaxis after ingestion of gelatin or administration of neomycin.
Rubella vaccination. The rubella live-virus vaccine is administered in one subcutaneous dose with no booster. It is indicated for all HCWs who do not have documentation of having received live vaccine on or after their first birthday or laboratory evidence of immunity. Adults born before 1957, except women who can become pregnant, can be considered immune.
Contraindications include pregnancy, immunosuppression and a history of anaphylaxis after ingestion of gelatin or administration of neomycin.
Varicella Zoster vaccination. This fairly new vaccine is administered in two subcutaneous doses four to eight weeks apart to those over age 12. It is indicated for all HCWs who do not have either a reliable history of chickenpox or serologic evidence of immunity.
Contraindications include pregnancy, immunosuppression and a history of anaphylaxis after receipt of gelatin or neomycin. Salicylate (aspirin, for example) use should be avoided for six weeks after vaccination.
Tuberculosis vaccination. Vaccination with the Bacille-Calmette-Guerin (BCG) vaccine involves one precutaneous dose with no booster. The BCG vaccine should be considered only for HCWs in areas where multidrug-resistant tuberculosis is prevalent, a strong likelihood of infection exists and where comprehensive infection-control precautions have failed to prevent tuberculosis transmission to HCWs.
Contraindications include pregnancy and immunosuppression. Although the BCG vaccine is used in many countries, the U.S. tuberculosis-control efforts are directed towards early identification, treatment and preventive therapy with isoniazid.
All are encouraged to read the complete CDC publication for full details, which include recommendations for postexposure use of immune globulins.
In case you missed it, this column in the March 1998 issue discussed the Bloodborne Pathogens Standard?s guidelines on recordkeeping policies for vaccinations.
Chris Miller is director of Infection Control Research and Services and professor of oral biology at Indiana University.
