Flu outbreak kills 7 even though residents were immunized

January 12th, 2015

After the flu deaths of seven immunized patients with severe neurological conditions, the Centers for Disease Control and Prevention is emphasizing today that rapid administration of antivirals may prevent similar deadly infections in high-risk people. The CDC report published today details an acute outbreak of respiratory infection that occurred in February 2011 in a Ohio residential facility for children and young adults with severe neurological and neurodevelopmental conditions. Among the 130 residents, 76 (58%) developed respiratory illness, and 13 became severely ill; seven of those patients died. All 13 patients who became severely ill had neurological and neurodevelopmental conditions (i.e., intellectual disability, epilepsy, cerebral palsy). These conditions had the dual detrimental effect of complicating diagnosis and worsening disease. Thus, if influenza is suspected in such patients, antiviral treatment should be given as soon as possible after symptom onset -- ideally within 48 hours.

“Treatment should not wait for laboratory confirmation of influenza,” the CDC emphasized.

Strikingly, all 13 severely ill residents reportedly were vaccinated with the influenza vaccine recommended for the 2010−11 influenza season. “Although vaccination is the best method for preventing influenza and its complications, its effectiveness varies depending on vaccine virus match and the age and health of the person vaccinated,” the CDC states. “Preliminary data for the 2010−11 influenza season indicate that influenza vaccine effectiveness was approximately 60% for all age groups combined. … Vaccine effectiveness, however, can be considerably lower in immunosuppressed persons or those with underlying medical conditions.”

The CDC investigation found that while 62% of the severely ill patients did receive antiviral treatment, but in half of the cases treatment fell outside the optimal 48-hour window. In addition, the first regimen of antiviral drug prophylaxis was not administered until 18 days after the first case of flu was confirmed. Clinicians caring for patients with neurologic and neurodevelopmental conditions should be vigilant for signs and symptoms that might indicate early respiratory illness and should initiate influenza antiviral treatment as soon as warranted, especially during influenza season. The CDC advised:

o Prompt testing for influenza and empiric antiviral treatment for these patients when influenza is suspected. o Antiviral chemoprophylaxis also should be provided to all eligible residents of long-term–care facilities during influenza outbreaks. o Health-care personnel should be vaccinated, and clinicians should continue to encourage influenza vaccination in these patients, given the challenges posed by diagnosis and their increased risk for severe influenza-related outcomes.