Last updated April 16
Overview
The Centers for Disease Control and Prevention (CDC) reported on April 2 that between Aug. 30, 2009, and April 3, 2010, there were 41,821 U.S. laboratory-confirmed influenza-associated hospitalizations in the United States, with 2,117 deaths (As of April 16, CDC concluded its Aggregate Hospitalizations and Deaths Reporting Activity for the 2009-2010 flu season; more information on statistics can be found on the CDC site).
The CDC says that almost all of the influenza viruses identified during the 2009-2010 flu season were 2009 H1N1 influenza A viruses, and remain similar to the viruses chosen for the 2009 H1N1 vaccine.
The virus contains a unique combination of gene segments from pigs, birds and humans, creating a novel strain of influenza. Persons with febrile respiratory illnesses should stay at home from work or school, to avoid spreading the infections (including influenza and other respiratory illnesses) to others in their community. In addition, frequent hand washing can lessen the spread of respiratory illness.
The CDC has gathered together a number of resources to create a comprehensive information page about H1N1 for physicians.
The Virginia Department of Health has created a Frequently Asked Questions document that could be a useful tool for you and your staff in responding to patient questions. The VDH Inquiry Center (1-877-ASK-VDH3) and PHIC@vdh.virginia.gov also are useful resources to answer questions about novel H1N1.
The three health departments of Virginia, Maryland and DC have launched a new Web site to provide information to the residents of the National Capital Region on where they can get H1N1 vaccination, including information that answers the question, "What to do if you get the flu?" The Virginia section of the site includes specific locations in the region where H1N1 vaccine will be available to the public -- including pharmacies, stores and community clinics.
Illness signs, symptoms and recommendations
Illness signs and symptoms have consisted of influenza-like illness (ILI) -- fever and respiratory-tract illness (cough, sore throat, rhinorrhea), headache, myalgias, vomiting and diarrhea.
Case definitions
- Influenza-like illness (ILI) is defined as fever (temperature of 100.5F/38C or greater), and a cough and/or sore throat in the absence of a known cause other than influenza
- Confirmed case: RT-PCR or viral culture is positive for H1N1 strain
- Suspected case: ILI symptoms (fever plus respiratory symptoms) plus rapid influenza-screening test is positive or negative
- Potential case: ILI symptoms (fever plus respiratory symptoms)
Given the rapidly evolving information pertaining to this situation, ALL patients who present with signs and symptoms of influenza-like illness should be considered for evaluation if clinical suspicion warrants such a work up.
Infection control practices
See Inova's guidelines for infection control (.pdf), from the Inova Influenza Strategy Team Physician Advisory Group.
Diagnostic evaluation procedure
Patients should be evaluated for influenza if they have an acute febrile respiratory illness or sepsis-like syndrome. Certain groups may have atypical presentations, including infants, the elderly and persons with compromised immune systems. Priority for testing includes persons who:
- Require hospitalization or
- Appear to be associated with a cluster of respiratory illness in a group setting (i.e., two or more cases in a nursing home, daycare or similar setting)
- Are at high risk for severe disease or
- Present with sepsis-like syndrome
Groups at higher risk for seasonal influenza complications include:
- Children less than 5 years old
- Persons aged 65 years or older
- Children and adolescents (less than 18 years) who are receiving long-term aspirin therapy and who might be at risk for experiencing Reye syndrome after influenza virus infection
- Pregnant women
- Adults and children who have chronic pulmonary, cardiovascular, hepatic, hematological, neurologic, neuromuscular, or metabolic disorders
- Adults and children who have immunosuppression (including immunosuppression caused by medications or by HIV)
- Residents of nursing homes and other chronic-care facilities.
For more information, see the CDC's Interim Guidance for the Detection of Novel Influenza A Virus Using Rapid Influenza Diagnostic Tests.
Antiviral treatment for suspect cases
Antiviral treatment should be prioritized for those patients who are hospitalized and those at high risk for complications from influenza. For more information, consult the CDC Web site.
The CDC recommends that healthcare providers should begin antiviral treatment as soon as possible for all patients hospitalized with suspected flu, even if flu has not been confirmed by laboratory testing. Because false-negative results for the 2009 H1N1 flu rapid diagnostic tests are frequent, even patients with negative results on such tests should be considered for antiviral treatment if clinically indicated. CDC also recommends prompt antiviral therapy for outpatients with suspected flu who have symptoms of lower respiratory tract illness or clinical deterioration, regardless of previous health or age, and that early antiviral treatment should be considered for patients with suspected or confirmed flu who are at higher risk for complications, such as children under the age of 2 and pregnant women, even if not hospitalized.
Oseltamivir (Tamiflu) use for children less than 1 year old has been approved by the U.S. Food and Drug Administration (FDA) under an Emergency Use Authorization (EUA); dosing for these children is age-based. Consult the CDC Web site for specific dosing recommendation.
These two antiviral agents are “Pregnancy Category C” medications. Consult the CDC Web site for more detailed information regarding usage in this category of patient.
Peramavir is a neuraminidase inhibitor that may be administered in an IV formulation, and is approved for use under Emergency Use Authorization by the FDA. It is available from the CDC for select patients who meet the criteria for known or suspected infection due to novel H1N1 influenza. It must be requested directly from CDC by the physician seeking its use. It is currently being tested in Phase III clinical trials, but enough information about its usage is known so as to make it available in select cases.
For a complete description of IV peramivir, visit the CDC's page on Emergency Use Authorization of Peramivir IV.
Antiviral chemoprophylaxis
Antiviral chemoprophylaxis with either oseltamivir plus rimantadine or amantadine, or zanamivir, is recommended for the following individuals:
- Household close contacts who are at high risk for complications of influenza (see above) of a confirmed or probable case.
- Healthcare workers or public health workers who were not using appropriate personal-protective equipment during close contact with a confirmed, probable, or suspect case of novel H1N1 virus infection during the case’s infectious period.
What is Inova Health System doing to respond?
Inova has the processes, people, skills and equipment needed to respond to this infectious disease. We’re collaborating closely with local, regional and federal health agencies to share information and ensure that we have the latest information and guidelines. We are prepared to assess patients, and process cultures via the Virginia Department of Health (VDH), if indicated. We are cooperating with the local and state health department to track and confirm any cases, as is mandated by the CDC.
Patients who present to our Emergency Departments with symptoms of fever, chills, cough, myalgias or GI symptoms will be evaluated by our protocols. Patients will be requested to wear masks, as will clinical staff when in contact with these patients. When appropriate, these patients will be treated in one of the negative-pressure airflow rooms in our EDs, to limit exposure to other patients and hospital personnel.
Our ED physicians will evaluate patients and order appropriate testing, including a Rapid Influenza Screen and influenza viral cultures. The VDH laboratory, which has the ability to confirm the presence of this new strain of influenza virus, will only accept and process the viral cultures after pre-approval criteria have been confirmed clinically. Our Emergency Departments and laboratories are able to contact the local health department for this pre-approval, and arrange for expedited transport to the VDH lab. If you see a case in your office, you could do the same.
What should you do to respond?
We encourage you, our community physicians, to evaluate and test suspect cases of H1N1 influenza in your offices. Ultimately, this is a clinical diagnosis. We are working with the VDH to facilitate access to screening kits. For those physicians who are unable to provide Rapid Influenza testing in their offices and request that patients showing symptoms of H1N1 have screening or diagnostic studies done at an Inova facility, we will follow the process described above. Only those patients that might meet the case definitions and are at risk for influenza should be referred for evaluation.
Patients who are not clinically ill, or who look clinically stable to go home, should be sent home, with close follow-up instructions regarding worsening of symptoms, including any onset of respiratory distress. Patients whom you think might be exhibiting signs and symptoms of influenza, but for whom you do not have the rapid-detection screening test, could be started on antiviral medications empirically. You can consult the local health department if your suspicion makes you think the patient warrants a definitive culture for testing. They will help facilitate this, most likely by asking you to refer the patient to the hospital emergency department for testing (not screening).
For further guidance, check out the Medical Offices and Clinics Pandemic Influenza Planning Checklist from the U.S. Dept. of Health and Human Services and the CDC.
Resources
The New England Journal of Medicine has a site devoted to H1N1:
The American College of Emergency Physicians has a number of pages on the Web:
Refer to these letters from the Virginia Department of Health for additional guidance:
See also these letters from local health departments:
