-[ [ [ [ [ [ [ [ [ [ [ [ [ [ [ [ [ [ [ [ [ [ [ [ [ [ [ [ [ [ [ [ [ [ [ [[volume 15 number ,~j1vision of Public Health http://health.state.ga.us The Georgia Epidemiology Report is a publication of the Epidemiology Section of the Epidemiology and Health Information Branch, Division of Public Health, Georgia Department of Human Resources This report contains excerpts from MMWR April 30, 1999/vol. 48/No. RR-4. The complete report and other information on influenza can be acces.~~d at Prevention and Control of Influenza: . -J~E~ff~~Tu~~i.'.fa~ .. ..... c~(fl~aed!oJflbt~~~:a~n~di;a.'ttaen.e.u' .!~g~'qt:ni!',~}'i ;;' ev6lryyeafi.fPisY1sl1a{1yqnfy . .needed.once. rhel/qshot and the pneumonia vacc.ine can be given at the sam6l time (in. different locations). See the website_, for more information .about pneumovax and influenza. Recommendations of the Committee on Immunization (ACIP) Advisory Practices Introduction Epidemics of influenza occur during the winter months nearly every year and are responsible for an average of approximately 20,000 deaths per year in the United States. Influenza viruses also can cause global epidemics of disease, known as pandemics, during which rates of morbidity and mortality from influenza-related complications can increase dramatically. Influenza viruses cause disease in all age groups. Rates of infection are highest among children, but rates of serious morbidity and mortality are highest among persons aged 65 years and persons of any age who have medical conditions that place them at high risk for complications from influenza. Influenza vaccine is the primary method for preventing influenza and its more severe complications. In this report from the Advisory Committee on Immunization Practices (ACIP), the primary target group for the influenza vaccination recommendations includes persons who are at high risk for serious complications from influenza, including approximately 34 million persons aged>= 65 years and approximately 32 million persons aged <65 years who have chronic underlying medical conditions (See Table 1.) Director Kathleen E. Toomey, M.D., M.P.H. Biology of Influenza Epidemiology and Health Information Branch Acting Director Kathleen E. Toomey, M.D., M.P.H. Acting State Epidemiologist Paul A. Blake, M.D., M.P.H. Epidemiology Section Chief Paul A. Blake, M.D., M.P.H. Influenza A and B are the two types of influenza viruses that cause epidemic human disease. Influenza A viruses are further classified into subtypes on the basis of two surface antigens: hemagglutinin (H) and neuiaminidase (N). Although both influenza A and B viruses undergo continual antigenic change ~.e., antigenic drift), influenza B viruses undergo antigenic drift less rapidly and are not divided into sub-types. Since 1977, influenza A (H1N1) viruses, influenza A (H3N2) viruses, and influenza B viruses have been in global circulation. A person's immunity to the surface antigens, especially hemagglutinin, reduces the likelihood of infection and the severity of disease if infection occurs. However, antibody against one influenza virus type or subtype confers little or no protection against another virus type or subtype. Furthermore, antibody to one strain of influenza virus might not protect against a distantly related strain of the same subtype. The constant development of antigenic variants through antigenic drift is the virologic basis for seasonal epidemics and the reason for the incorporation of one or more new virus strains in each year's influenza vaccine. Public Health Advisor Mel Ralston Georgia Epidemiology Report Editorial Board Carol A. Hoban, M.S., M.P.H. - Editor Kathryn E. Arnold, M.D. Jeffrey D. Berschling, M.P.H. Paul A. Blake, M.D., M.P.H. Jane E. Koehler, D.V.M., M.P.H. Kathleen E. Toomey, M.D., M.P.H. Angela Alexander - Mailing List Jimmy Clanton, Jr. - Graphics Clinical Signs and Symptoms of Influenza Uncomplicated influenza illness is characterized by the abrupt onset of constitutional and respiratory signs and symptoms (e.g., fever, myalgia, headache, severe malaise, sore throat, rhinitis, and nonproductive cough). Illness typically resolves after several days for most persons, although cough and malaise can persist for 2 or more weeks. In some persons, influenza can exacerbate underlying medical conditions (e.g., pulmonary or cardiac disease) or lead to secondary bacterial pneumonia or primary influenza viral pneumonia. Georgia Department of Human Resources Division of Public Health, Epidemiology Section Epidemiology & Health Information Branch Two Peachtree St., N.W., Atlanta, GA 30303 - Phone: (404) 657-2588 Fax: (404) 657-2608 3186 Table 1. Target Groups for Influenza Vaccination Persons at High Risk for Influenza-Related Complications Persons aged >=65 years Residents of nursing homes and other chronic-care facilities that house persons of any age who have chronic medical conditions Adults and children who have chronic disorders of the pulmonary or cardiovascular systems, including asthma Adults and children who have required regular medical follow-up or hospitalization during the preceding year because of chronic metabolic diseases (including diabetes mellitus), renal dysfunction, hemoglobinopathies, or immunosuppression Qncluding immunosuppression caused by medications) Children-and teenagers (~ed-6 months to 18 years) who are receiving long-term aspirin therapy and therefore might be at risk for developing Reye syndrome after influenza Women who will be in the second or third trimester of pregnancy during the influenza season. (Pregnant women who have medical conditions that increase their risk for complications from influenza should be vaccinated before the influenza season - regardless of the stage of pregnancy)*. Persons Who Can Transmit Influenza to Those at High Risk Physicians, nurses, and other personnel in both hospital and outpatientcare settings Employees of nursing homes and chronic-care facilities who have contact with patients or residents Employees of assisted living and other residences for persons in high-risk groups Persons who provide home care to persons in high-risk groups Household members (including children) of persons in high-risk groups Consider also: Persons infected with Human Immunodeficiency Virus (HIV)* Breast feeding mothers* Travellers* General population* Options for Controlling Influenza In the United States, the main option for reducing the impact of influenza is immunoprophylaxis with inactivated (i.e., killed virus) vaccine. In addition, the use of influenza specific antiviral drugs (amantadine or ,,---.. rimantidine) for chemoprophylaxis or therapy of influenza A infection is / important adjunct to vaccine. Influenza Vaccine Vaccinating persons at high risk for complications before the influenza season each year is the most effective means of reducing the impact of influenza. Vaccination coverage can be increased by administering vaccine to persons during hospitalizations or routine health-care visits before the influenza season, making special visits to physicians' offices or clinics unnecessary. When vaccine and epidemic strains of virus are well matched, achieving high vaccination rates among persons living in closed settings (e.g., nursing homes and other chronic-care facilities) and among the staff can reduce the risk for outbreaks by inducing herd immunity. Influenza Strains Contained in the 1999-2000 Vaccine The trivalent influenza vaccine prepared for the 1999-2000 season will include A/Beijing/262/95-like (H1N1), A/Sydney/5/97-like (H3N2), and B/Beijing/184/93-like hemagglutinin antigens. For the B/Beijing/184/ 93-like antigen, U.S. manufacturers will use the antigenically equivalent B/ Yamanashi/166/98 virus because of its growth properties and because it is representative of currently circulating B viruses. Recommendations For The Use Of Influenza Vaccine Influenza vaccine is strongly recommended for any person .------, aged>= 6 months who - because of age or underlying medical condition - is at increased risk for complications of influenza. In addition, health-care workers and others (including household members) in close contact with persons in high-risk groups should be vaccinated to decrease the risk of transmitting infection to persons at high risk. Influenza vaccine also can be administered to any person who wishes to reduce the chance of becoming infected with influenza (the vaccine can be administered to children as young as 6 months) See Table 1. Strategies for Implementing These dations in Health-Care Settings Recommen- Successful vaccination programs combine education for healthcare workers, publicity and education targeted toward potential recipients, a plan for identifying persons at high risk (usually by medical-record review), and efforts to remove administrative and financial barriers that prevent persons from receiving the vaccine. Persons for whom influenza vaccine is recommended can be identified and vaccinated in the settings described in the following paragraphs. Persons Who Should Not Be Vaccinated Persons known to have anaphylactic hypersensitivity to eggs or to other components of the influenza vaccine without first consulting a physician* Persons with acute febrile illness usually should not be vaccinated until their symptoms have abated. * . * See complete MMWR report for more information and commentary Nursing Homes and Care Facilities Other Residential Long-Term Vaccination should be routinely provided to all residents of chronic-care facilities with the concurrence of attending physicians. Consent for vaccination should be obtained from the resident or a family member a~ the time of admission to the facility or anytime afterwards. All residents . should be vaccinated at one time, immediately preceding the influenza season. Residents admitted during the winter months after completion of the vaccination program should be vaccinated at the time of admission. -2- Visiting Nurses to Persons at and High Others Risk Providing Home Care Nursing-care plans should identify patients in high-risk groups, and vaccine should be administered in the home if necessary. Care givers and other '"'= 65 Years In facilities such as assisted-living facilities, retirement communities, and recreation centers, unvaccinated residents and attendees should be offered vaccine on site before the influenza season. Staff education should emphasize the need for influenza vaccine. RECOMMENDATIONS FOR THE USE OF ANTIVIRAL AGENTS FOR INFLUENZA A Amantadine was approved in 1976 for the treatment and prophylaxis of influenza type A virus infections in adults and children aged>= 1 year. Rimantadine was approved in 1993 for treatment and prophylaxis of infection in adults. Although rimantadine was approved only for prophylaxis of infection in children, many experts consider it appropriate for treatment among children. Amantadine and rimantadine differ in terms of pharmacokinetics, side effects, and costs. In particular, rimantadine is associated with fewer central nervous system side effects than amantadine, but it is more expensive. Antiviral drugs for influenza are an important adjunct to influenza vaccine for the control and prevention of influenza. The currently licensed agents are amantadine hydrochloride and rimantadine hydrochloride, which are chemically related antiviral drugs with specific activity against influenza A "uses but not influenza B viruses*. - _ootnote: Since the publication of these recommendations, the Food and Drug Administration has also approved zanamivir, a neuraminidase inhibitor (NI) with activity against both influenza A and B viruses, for treatment of adults and adolescents aged 12 years and older. A second NI, oseltamivir, may be available in the near future. The reader should consult package inserts for information until public health guidelines for use are available. Indications for Use Amantadine and rimantadine are indicated for the prophylaxis and treatment of influenza A infection. When administered prophylactically to healthy adults or children, both drugs are approximately 70%-90% effective in preventing illness from influenza A infection. When used as prophylaxis, one benefit of these antiviral agents is that they can prevent illness while permitting subclinical infection. Therefore, some persons who take these drugs will develop protective immune responses to circulating influenza viruses. When administered as treatment within 48 hours after illness onset in healthy adults, amantadine and rimantadine can reduce the severity and duration of signs and symptoms of influenza A illness. Studies of the efficacy of either amantadine or rimantadine treatment in children are limited. When institutional outbreaks occur, chemoprophylaxis should be administered to all residents - regardless of whether they received influenza vaccine during the previous fall - and continued for at least 2 weeks or until approximately 1 week after the end of the outbreak. The individual dosage for each resident should be determined. Chemoprophylaxis also can be offered to unvaccinated staff who provide care to persons at high risk. Prophylaxis should be considered for all employees, regardless of their vaccination status, if the outbreak is caused by a variant strain of influenza A that is not well matched by the vaccine. Chemoprophylaxis also can be considered for controlling influenza A outbreaks in other closed or semiclosed settings (e.g., dormitories or other settings where persons live in close proximity). Whenever any institutional outbreak occurs, measures should be taken to reduce contact as much as possible between persons taking antiviral drugs for treatment and other persons, including those taking chemophrophyla..xis, to limit the potential transmission of drug-resistant virus. ROLE OF VIRAL DIAGNOSIS The appropriate treatment of patients with viral respiratory illness depends on accurate and timely diagnosis. The early diagnosis of influenza also can help reduce the inappropriate use of antibiotics, a growing major public health problem. Currently, several commercial assays are available that can be used in a clinic setting to rapidly (30 minutes or less) detect influenza viruses, and additional commercial assays are available for use by laboratories. No published study has directly compared the sensitivity, specificity, positive predictive value, and negative predictive value of these assays for detecting influenza in clinical specimens. The use of viral culture, in addition to rapid diagnostic tests, remains critical, because only cultures yield viruses that can be characterized to provide specific information on circulating influenza subtypes and strains. This information is needed to assess the match between current circulating and vaccine strains and to help formulate vaccine for the coming year. Sources of information on influenza and its surveillance. Available October through May: Georgia: CDC: Voice information: 888-232-3288 Fax information: 888-232-3299 Website: Georgia's Division of Public Health would like to extend our thanks to the 62 medical providers statewide who participated in the influenza surveillance system for 1998-1999. Thanks to you, we were able to characterize the onset of influenza in Georgia (mostly influenza B, initially), detect widespread onset of influenza A viral outbreaks, and determine influenza strains occurring locally. For information about participation in the surveillance system, please contact Carol Hoban, Influenza Surveillance Coordinator. Use of Antiviral Drugs for the Control of Influenza Outbreaks in Institutions Most published reports on the use of antiviral drugs to control institutional outbreaks of influenza are based on studies of nursing home "oulations. When confirmed or suspected outbreaks of influenza A occur in tutions that house persons at high risk, chemoprophylaxis should be ----- .