COMMENTARY

Antivirals, Not Antibiotics, for Influenza

Fiona Havers, MD, MHS

Disclosures

October 27, 2014

Editorial Collaboration

Medscape &

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Hello. I am Fiona Havers, a medical officer and physician in the Influenza Division at the Centers for Disease Control and Prevention (CDC). I am happy to speak with you as part of the CDC Expert Commentary Series on Medscape.

Today I would like to discuss the importance of appropriate influenza antiviral treatment in patients with confirmed or suspected influenza, as well as the dangers of overprescribing antibiotics.

Recently I authored a CDC study[1] that examined clinician treatment practices for outpatients with influenza during the 2012-2013 season. Key findings showed that clinicians commonly underprescribed the influenza antiviral drugs oseltamivir and zanamivir, and potentially overprescribed common antibiotics to patients with influenza for whom antiviral therapy would have been most beneficial.

Overall, only 16% of patients with laboratory-confirmed influenza received antiviral treatment, whereas 30% were prescribed one of three common antibiotics. Perhaps even more concerning is that only 19% of patients at high risk for influenza complications and who had respiratory symptoms for fewer than 2 days—a group likely to benefit from antiviral therapy—were prescribed an antiviral medication.

For people with high-risk medical conditions, treatment with an influenza antiviral drug can mean the difference between milder illness and a serious illness that could result in hospitalization. People at high risk for influenza complications include adults 65 aged years and older, young children, pregnant women, and people with underlying medical conditions, such as chronic obstructive pulmonary disease, asthma, congestive heart failure, and diabetes.

CDC recommends early antiviral treatment with the neuraminidase inhibitors (oseltamivir and zanamivir), ideally within 2 days of illness onset, for people with suspected or confirmed influenza illness who are hospitalized or have severe or progressive illness, and for outpatients who are at high risk of developing complications from influenza. Early neuraminidase inhibitor antiviral treatment for outpatients who are not at high risk for complications can reduce symptoms related to influenza by 1-2 days, and can be prescribed on the basis of clinician clinical judgment.

A growing body of evidence from observational studies shows the clinical benefit of early antiviral treatment in reducing risk for death in hospitalized patients with influenza. A large meta-analysis[2] conducted across 38 countries and involving more than 29,000 patients during the 2009 pandemic showed that treatment of adults with neuraminidase inhibitor antiviral drugs reduced the risk for death by 25% compared with no antiviral treatment. Early treatment was more effective, reducing the risk for death in adults by 60%.

A study[3] that analyzed the combined data from 11 randomized controlled trials of outpatients with influenza found clinical benefit of early oseltamivir treatment, compared with placebo, in reducing the risk for lower respiratory tract complications, such as those that require antibiotics. Unfortunately, these studies do not have the power to evaluate the effect of outpatient treatment to prevent hospitalization, a point that was raised by a Cochrane analysis[4] published in April 2014. Other findings of the Cochrane analysis were consistent with the original clinical trials that demonstrated a reduction in symptoms from early oseltamivir treatment among healthy individuals with influenza infection.

Prescribing antibiotics for acute respiratory illness is often inappropriate and can put patients at risk for allergic reactions, antibiotic-resistant infections, and potentially deadly diarrhea caused by Clostridium difficile. Antibiotics do not have activity against viruses.

Clinicians who see high-risk patients in an ambulatory setting can reduce patients' symptoms and risk of developing more serious complications from influenza by providing antiviral treatment when there is clinical suspicion of influenza infection.

In patient populations for whom antiviral treatment is indicated, therapy should ideally be started within 48 hours of symptom onset, even before laboratory test results are available. Clinicians caring for hospitalized patients with suspected influenza should begin antiviral treatment as soon as possible, regardless of whether high-risk conditions are present. Although early treatment is optimal, observational data[5] suggest that antiviral treatment might still be beneficial in hospitalized patients when started later than 48 hours after illness onset.

Appropriate prescribing of both antibiotic and antiviral agents is essential to improving healthcare quality. Vaccination to prevent influenza infection and prompt antiviral therapy to treat influenza illness are the most important medical countermeasures against influenza. Their correct application by healthcare professionals can provide life-saving benefits to patients.

A summary of CDC's antiviral guidance, including dosing information for children, is available online.

Fiona Havers, MD, MHS, is a medical officer for the Influenza Prevention and Control Team, Epidemiology and Prevention Branch, Influenza Division, within CDC's National Center for Immunization and Respiratory Diseases. Dr Havers earned her doctor of medicine degree from the University of Washington in 2007 and completed training in internal medicine and infectious diseases at the Johns Hopkins University. She obtained a master's of health science in epidemiology from the Johns Hopkins Bloomberg School of Public Health. Dr Havers also completed the Epidemic Intelligence Service training in the Influenza Division at CDC and is board certified in internal medicine and infectious diseases.

While at CDC, Dr Havers' research interests have focused on the epidemiology, prevention, and treatment of influenza. Her research includes studies on the impact of seasonal influenza on children with neurologic disorders and on respiratory viruses in children in Bangladesh. She also assisted the Chinese government in the outbreak investigations of a novel avian influenza in China in 2013, and assisted in the investigation of a novel influenza virus circulating in the Midwest in 2012. Her current primary research focuses on influenza antiviral treatment as well as influenza vaccine effectiveness.

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