Genesee County Health Department

Better Life Through Better Health

Release Date:       January 28, 2009        End Date:  February 27, 2009

Contact Person:    Fatema Mamou

                              Epidemiologist

                              Genesee County Health Department

Phone:                  (810) 768-7971

RE:      Antiviral drug resistance in one circulating influenza virus strain 

Samples from people who have been infected with the flu virus this season have revealed that a high percentage of one of the circulating strains is resistant to an antiviral medication commonly used to treat the infection. The H1N1 subtype of the influenza A virus that is currently circulating has become resistant to oseltamivir, also known as Tamiflu®. There are other drugs that can be used to treat influenza A H1N1. The Genesee County Health Department (GCHD) is advising health care providers to follow the interim recommendations for the use of influenza antiviral medications this flu season issued by the Centers for Disease Control and Prevention (CDC).

The best way to prevent influenza is with the annual influenza vaccine. It is still not too late to get vaccinated this season. The flu vaccine this year is effective at preventing infection with the oseltamivir-resistant influenza A H1N1 viruses. The vaccine is recommended for anyone 6 months of age or older who wants to reduce his or her chances of getting the flu. Certain people should get vaccinated each year such as those who are at high risk of having serious flu complications or people who live with or care for those at high risk for serious complications from influenza. The GCHD encourages anyone who has not yet received a flu vaccination this season to get one now. Plenty of influenza vaccine is available this year. The GCHD has two immunization clinics that offer influenza vaccine.

Two influenza A viruses, subtypes H1N1 and H3N2, and various influenza B viruses currently circulate worldwide. The influenza A H1N1 virus is the cause of most influenza infections in United States right now, but it is still too early to predict which virus will be the most common. Health care providers can perform rapid tests for influenza that will tell whether a patient is infected with influenza A or influenza B virus, which, along with local influenza data, will help guide antiviral treatment. Infection with influenza A H1N1 virus has been confirmed in a Genesee County resident. According to the CDC recommendations, health care providers should treat patients who are suspected to be infected with or exposed to influenza A H1N1 with an antiviral drug called zanamivir or a combination of oseltamivir and rimantadine, another antiviral drug. Antiviral drugs must be prescribed by a health care professional and can help reduce symptoms when started within 2 days after becoming sick with influenza.

Data from schools and childcare facilities in Genesee County indicate that local cases of flu-like illnesses are increasing, but remain at a low level and are below what was seen at this time last year. Current influenza activity in Michigan is beginning to rise but is also at a low level. Last week the Michigan Department of Community Health upgraded Michigan’s flu activity from “sporadic” to “local” due to a small, steady increase in southeast Michigan. In the past two years the influenza season in the United States peaked in mid-February.

Please visit the Genesee County Health Department web site at www.gchd.us for further information and resources regarding influenza and the times and locations of the GCHD immunization clinics. Health care providers can visit www.gchd.us or call (810) 768-7971 for further information on the use of antiviral medications this influenza season, current influenza surveillance data, and information about laboratory testing.

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