Pertussis Vaccination of Health Care Workers
IntroductionInfection with Bordetella pertussis, the cause of whooping cough, is common in the adult and adolescent population because immunity from prior illness or childhood vaccination is not life-long. As many as 800,000 to 3.3 million cases of pertussis may occur annually in the United States, and many adults and adolescents with cough lasting longer than 5 days may suffer from the disease. Because pertussis causes cough for prolonged periods of time, and the organism spreads readily from person to person, adults may spread it unwittingly to vulnerable infants who are unprotected or not fully protected by acellular pertussis vaccine.
Health care environments have been the setting for a number of pertussis outbreaks. Health care workers are at risk for occupational infections with pertussis and at risk for inadvertently transmitting pertussis to vulnerable patients, particularly the very young. An acellular pertussis vaccine was approved in 2005 by the US Food and Drug Administration (FDA) for adults and adolescents, and provisional recommendations from the US Centers for Disease Control and Prevention’s (CDC’s) Advisory Committee on Immunization Practices (ACIP) call for its administration to the general population and, specifically, as soon as feasible to health care personnel who work in hospitals or ambulatory care settings and have direct patient contact. The American College of Occupational and Environmental Medicine (ACOEM) issues this position statement in support of that recommendation. The College’s support of the recommendation is based on current knowledge of the epidemiology of pertussis, its transmission characteristics, documented risk in patient care settings, and efficacy of the newly approved vaccine.
Epidemiology of Pertussis
The number of reported pertussis cases has risen dramatically in recent years. A low of 1,010 cases was reported in 1976, compared to 25,827 cases in 2004. Age group distribution has also changed, with adolescents and adults comprising an increasing proportion of the total. The rise in reported illness is likely due to increased use of diagnostic testing to detect pertussis in adults, and may also reflect an increased disease frequency.
However, reported cases represent only the tip of the iceberg. A recent trial of acellular pertussis vaccine evaluated the incidence of pertussis in a control population by testing for B. pertussis infection whenever prolonged cough occurred. Incidence of infection ranged from 370 to 450 cases per 100,000 person-years. Extrapolating that rate to the total US population suggests that there are nearly 1 million pertussis cases per year among those aged 15 to 65 years in the US.1 A number of other studies have yielded similar results, with estimates ranging from a US annual incidence of 800,000 to 3.3 million cases per year.2
Estimates vary regarding how frequently pertussis is the causal agent when a person suffers prolonged cough. A recent report reviewed 13 studies carried out since 1987 addressing pertussis frequency among adolescents and adults. Results varied widely due to the criteria used to assign a diagnosis of pertussis and whether the study was performed during a pertussis outbreak. Among studies done when no known pertussis outbreak was occurring, an estimated 12% to 50% of chronic cough illnesses were associated with pertussis infection. When only the most specific diagnostic criteria were used in non-outbreak settings, a median 13% of chronic cough illnesses were due to pertussis.2
Clinical Characteristics and Disease Transmission
Because pertussis is often unrecognized among adolescents and adults and because the disease is highly contagious for a period of several weeks (80% of susceptible household contacts become infected with pertussis), the large case reservoir represents a substantial threat to those unprotected or incompletely protected by vaccine. Infants under 6 months are the most vulnerable group and make up 90% of pertussis-related mortality. Between 2001 and 2003, for example, 42 children under the age of 2 months died from the disease.3 Pertussis is most contagious during its early catarrhal stage, when infected persons experience only runny nose, sneezing, low-grade fever, and mild occasional cough, similar to the common cold. It is not until the paroxysmal stage, characterized by coughing fits and prolonged inspiratory phase, that pertussis is likely to be clinically suspected and diagnosed. Nearly 80% of adults with confirmed pertussis have an illness involving a cough of at least 3 weeks’ duration, and 27 percent have cough lasting longer than 90 days.4
The Health Care Setting
In health care settings, where despite recommendations to the contrary, health care workers frequently remain on the job with respiratory symptoms, the threat of transmission from symptomatic, but undiagnosed health care workers to vulnerable patients is very real. A number of pertussis outbreaks have occurred in hospital resulting in transmissions to health care workers, vulnerable infants, and other patients.5,6 Those outbreaks also have resulted in labor intensive contact tracing and administration of prophylactic antibiotics to large numbers of exposed individuals.
Adult Acellular Pertussis Vaccine (Tdap)
In 2005, the FDA gave approval to two new acellular pertussis vaccines, one approved for use in adolescents, the other approved for persons aged 11 to 64. The vaccines (referred to as Tdap) contain pertussis antigens in a reduced quantity compared to the pediatric formulation and similar amounts of tetanus and diphtheria toxoids to the tetanus/diphtheria booster vaccines currently in use in the adult population. Vaccine efficacy for pertussis is 92%, and the side effect profile does not differ significantly from the currently used tetanus and diphtheria booster vaccine.1 Most common side effects are pain, redness, or swelling at the injection site. Other reported symptoms include headache, fatigue, and gastrointestinal symptoms. No serious adverse events have been attributed to Tdap.3
Advisory Committee on Immunization Practices (ACIP) recommendations for administration of Tdap to adolescents have been published by the CDC. ACIP voted in October 2005, to approve recommendations for administration of Tdap to adults in the general population, and in February 2006, ACIP voted that Tdap should be administered as soon as feasible to all health care workers who are employed in hospitals and ambulatory settings and have direct patient contact. Targeted groups include – but are not limited to – physicians, other primary care providers, nurses, aides, respiratory therapists, radiology technicians, students (medical, nursing, and other), dentists, social workers, chaplains, volunteers, and dietary and clerical workers. The recommendation for administration in health care settings is based on heightened transmission risk in health care settings, the need to protect vulnerable patients, particularly infants from pertussis, and the desire to minimize transmission risk to health care workers. The recommendation assigns highest priority to health care workers who have contact with infants <12 months old, and encourages health care institutions to utilize methods shown to maximize vaccination rates, namely education about the benefits of vaccination, convenient access, and the provision of Tdap to health care workers at no charge. Further study is needed to determine whether vaccination will obviate the need for post-exposure antibiotic prophylaxis of adults.
ACOEM Position
As the largest professional organization concerned with the prevention and management of occupational exposures, injuries and illnesses, ACOEM endorses the ACIP provisional recommendation that Tdap be administered as soon as feasible to health care workers with direct patient contact as a vital step to protect both health care workers and patients. While initial cost to administer Tdap to large numbers of health care workers will be high (approximately $30/dose), a recent cost-benefit analysis found that vaccination of health care workers will actually result in net savings to hospitals.7 Yearly expenses to administer vaccine will also decrease after the first year. Although licensed for a single dose, it is anticipated that for continued protection from pertussis, additional doses will be required every 10 years. With wider vaccination coverage, the general population will gradually contain a larger proportion of vaccinated individuals.
Occupational medicine physicians in hospital settings bring vital experience in the management of vaccine campaigns to this important public health issue. It is expected that initial Tdap administration will be most successfully accomplished by using techniques already shown to be successful in influenza vaccination campaigns, and many occupational medicine physicians may choose to fold Tdap administration into those campaigns. Some may favor a tiered approach, vaccinating first those with direct infant contact. In many hospitals, occupational medicine physicians, in cooperation with colleagues in infection control, will need to present the case to hospital administrators that expenditures for Tdap administration are justified by patient safety and health care worker protection.
Pertussis is a disease which kills otherwise healthy infants in the US. Until its epidemiology is fundamentally altered by eliminating the large reservoir of adult and adolescent cases, infants will continue to die from it. Because the most vulnerable of the very young are treated in hospitals, administration of Tdap vaccine as soon as feasible to health care workers will reduce the likelihood of devastating outcomes among such patients. It will also provide vital protection to millions of US health care workers at enhanced exposure risk from pertussis. ACOEM fully supports pertussis vaccination of health care workers with direct patient contact, and urges physicians in its membership who oversee occupational health programs in medical centers to assign high priority to vaccinating health care workers as soon as feasible.
References
This statement was developed byMark Russi, MD, MPH, Associate Professor of Medicine and Public Health, Yale University School of Medicine, Director, Occupational Health, Yale-New Haven Hospital, and endorsed by the ACOEM Medical Center Occupational Health Section. It was approved by the ACOEM Board of Directors on May 9, 2006.
Copyright©2006 American College of Occupational and Environmental Medicine
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