Influenza and Pneumococcal VaccineContinual antigenic drift of the influenza virus means that a new vaccine, updated yearly with the most current strains in circulation is needed to protect against new infections. Influenza vaccine is recommended for people at high risk for influenza-related complications. This includes people >65 years of age and adults and children with chronic conditions, such as diabetes, immunodeficiency, renal disease, immunosuppression, anemia, and chronic pulmonary or cardiac disorders. Also included are individuals capable of transmitting influenza to those at high risk for influenza-related complications, such as health care workers and household contacts. The effectiveness of influenza vaccine varies depending upon the age and immunocompetence of the vaccine recipient, the degree of similarity between the virus strain included in the vaccine and the strain of circulating virus during the influenza season. With a good match, influenza vaccine has been shown to prevent laboratory confirmed influenza illness in approximately 70% to 90% of healthy adults. Under these circumstances, studies have also shown influenza vaccination to be approximately 70% effective in preventing hospitalization for pneumonia, and influenza among elderly persons living in the community. Studies among elderly persons residing in nursing homes have shown influenza vaccinations to be 50% to 60% effective in preventing hospitalization and pneumonia and >85% effective in preventing death, even though efficacy in preventing influenza illness may often be in the range of 30% to 40% among the frail elderly. Only 70% to 91% of long term care facility residents and 20% to 40% of adults and children with medical conditions listed previously receive vaccine annually. Studies of health care workers in hospitals and long term care have shown vaccination coverage rates of 26% to 61%. (1) Physicians can improve rates of vaccination by educating patients about the common concerns regarding the effectiveness and the benefits of vaccination. The advice of a health care provider is often a very important factor determining whether or not a person is immunized. Immunization of health care workers in health care facilities has been shown to reduce total patient mortality, influenza-like illness and serologically confirmed influenza. (1) Influenza immunization programs for health care workers may also result in cost savings and reduced work absenteeism. Ontario made influenza vaccine available to all its citizens at no charge in the 2000-2001 influenza season and again in the 2001-2002 season. As clearly stated by the Ontario government, the aim is to ease pressure on emergency services during the influenza season. (2) Whether this will be a major advance in influenza control, or reduce the burden of influenza, has not yet been evaluated. The potential additional benefits include protecting vulnerable populations, improving high-risk coverage, reducing community transmission and improving preparedness for a pandemic. The "con" side argues that given the cost of the Ontario program ($38 million in 2000-2001) and the quality of information available; it is unclear if universal immunization will be introduced elsewhere. (2) In the United States the Advisory Committee on Immunization Practice (ACIP) now recommends that Influenza vaccine be administered to persons aged 50 to 64 years of age because of the increased prevalence of persons with high risk conditions.(3) Whether this is a more effective way to increase the coverage of the high risk groups in that age group compared to a targeted approach is yet to be determined. The low rate of health care worker immunization is due to both the failure of the health care system to offer the vaccine, and to refusal by persons who fear adverse reactions or mistakenly believe the vaccine is either ineffective or unnecessary. HCW's and their employers have a duty to actively promote, implement and comply with influenza immunization recommendations in order to decrease the risk of infection and complications in the vulnerable population under their care. Educational efforts should be aimed at physicians and the public to address common concerns about vaccine effectiveness and adverse reactions. In particular, efforts should target changing the beliefs of patients at risk and the beliefs of health care workers who may think that they are rarely susceptible to influenza. Studies have demonstrated that HCW's who are ill with influenza often continue to work.(1) In a British Columbia study, 59% of HCW's with serologic evidence of recent influenza infection could not recall having influenza, suggesting that many HCW's experience subclinical infection. These individuals continued to work, potentially transmitting infection to their patients. In addition, absenteeism of health care workers who are sick with influenza results in excess economic costs and, also potential endangerment of health care delivery due to scarcity of replacement workers.(1) In January, 2001 Health Canada commissioned a random digit dialing telephone survey to evaluate the influenza immunization coverage for persons >65 years of age and those at high risk for complications. (4) The survey interviewed 3501 non-institutionalized Canadian residents >18 years of age, from all provinces and territories. The recently published results indicate that among those interviewed who were >65 years of age, 69% received influenza vaccination during the 2000 - 2001 influenza season. However, only 38% of those 18 to 64 years of age who have high risk medical conditions, and 55% of health care workers who have close contact with patients, were immunized during this season. Greater efforts are required to improve influenza immunization coverage rates in these high-risk groups. (4) Recommendations:
Thanks to Dr. Graham L. Pollett MD,MHSc,FRCPC Medical Officer Of Health Middlesex London Health Unit, London Ontario for reviewing the draft copy of this article. References:
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