A new report illustrates just how deadly influenza can be among children and young adults with neurological and neurodevelopmental disorders.

In a single Ohio residential facility last year, flu killed half of the patients in this population who developed a serious case. The case study points up the need for aggressive disease detection and treatment among this population, Dr. Mary DiOrio and colleagues reported in the Jan. 6 issue of the Morbidity and Mortality Weekly Report (MMWR 2012;60:1729-33).

"Prompt testing, early and aggressive antiviral treatment, and antiviral chemoprophylaxis are important for these patients," wrote Dr. DiOrio and her coauthors. "When influenza is suspected, 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."

All eligible residents and all staff members should be vaccinated each year, but during a flu outbreak all residential patients should also receive chemoprophylaxis with an antiviral medication, regardless of their vaccination status, the authors noted.

Dr. DiOrio, an epidemiologist for the Ohio Department of Health, and her coauthors reported on a 2011 flu outbreak in an Ohio facility that cares for children and young adults with neurologic and neurodevelopmental conditions. The outbreak ran for 6 weeks, from the beginning of February to the second week in March.

"When influenza is suspected, antiviral treatment should be given as soon as possible after symptom onset, ideally within 48 hours."

During the outbreak, 76 of the 130 (58%) patients experienced an acute onset of respiratory illness. Thirteen were severely ill; seven had influenza confirmed by laboratory testing and six had a suspected case. All of these had severe to profound neurologic and neurodevelopmental disabilities; nine had "do not resuscitate" orders.

All of the patients also had been vaccinated for the seasonal flu the previous fall. However, Dr. DiOrio’s investigation also revealed that the vaccine storage temperature might have affected its potency. The temperature of the storage refrigerator ranged from 10°-42° F during the investigation, with a mean of 27° F, which is below the vaccine’s recommended limit temperature.

The mean duration of illness was 18 days. Fever was the most common presenting sign, occurring in 12 patients. All seven deaths were due to respiratory failure secondary to influenza. Other diagnoses at the time of death or hospital discharge were pneumonia (5), septic shock (2), acute respiratory distress syndrome (2), and multiple organ failure (1).

Most of the cases (72) occurred before Feb. 28. Seven of the severe cases occurred from Feb 23-28. However, Dr. DiOrio noted, none of the facility residents received any oseltamivir prophylaxis until Feb 28. Eight of the cases received oseltamivir, but only four got the drug within 48 hours of symptom onset, as recommended for maximum benefit.

Although oseltamivir works best if administered within the first 48 hours of symptom onset, it can still mitigate the course of illness if given later. "Recent observational data indicate that, even when started more than 48 hours after illness onset, treatment can help prevent influenza-related complications and death in persons at higher risk or with more severe illness," the Centers for Disease Control and Prevention wrote in an editorial note.

While preventing flu with vaccination is the most effective way to combat the disease, vaccination may not completely protect patients who may have comorbid immunosuppression due to their medical status. "Because [these] persons ... are at high risk for complications and the vaccine might not protect them fully, vaccination should be one part of a larger program of influenza prevention in these settings," according to the CDC.