IDSA studies report on range of flu issues

Robert Roos

Oct 21, 2010 (CIDRAP News) – Influenza reports presented at the Infectious Diseases Society of America's (IDSA's) annual conference today shed light on a range of topics, including vaccine acceptance among healthcare workers (HCWs) and risk factors for hospitalization in small children.

IDSA members discussed their reports in a press teleconference today from the meeting site in Vancouver, B.C., and the organization also released abstracts online.

Three studies dealing with flu vaccination mandates for HCWs suggested that workers will generally accept such requirements, especially if they are preceded by years of education, but may still regard them as coercive.

A study of risk factors for flu complications in children under age 5 indicated that household smoking, having a very young mother, and poverty all increase a child's risk of being hospitalized with confirmed flu.

Another study found that Asians were disproportionately represented among Californians who had seizures in connection with severe illness during the 2009 H1N1 pandemic.

Vaccination mandates for health workers
Archana Chatterjee, MD, PhD, of Creighton University in Omaha reported on the experience in promoting HCW vaccination at Children's Hospital and Medical Center of Omaha over a 12-year period. She said an effort to educate workers and respond to their concerns boosted immunization rates for several years, so that when a mandate was finally imposed in 2009, it was well accepted.

Chatterjee said the improvements began after the hospital recruited an employee health nurse in 2003. Subsequent measures that were helpful included such things as walk-in vaccination times during the nurse's business hours, taking the "flu cart" to patient care areas, Saturday immunization sessions for workers and their families, and signed declination forms, according to the abstract of her presentation.

The immunization rate reached 86% without a mandate in 2008, Chatterjee said. After the mandate was implemented last year, "We did not have protests, we did not have people refusing the vaccination when it came to the mandate," she said. "I think the reason is that in previous years we had worked with employees to respond to their concerns and educate them."

Kristen Feemster, MD, MPH, reported on the implementation of a flu vaccination mandate and subsequent survey of HCW attitudes at Children's Hospital of Philadelphia.

The hospital's staff immunization rate reached 90% in the 2008-09 flu season with a voluntary program, she reported. Last year a mandate was implemented, which boosted the rate to more than 99%. Fifty-two workers received medical or religious exemptions, and nine were fired for refusing the vaccine.

The employee survey drew responses from 1,371 staffers, about half of them clinical workers. Most of them (72%) thought the mandate was "coercive," but more than 90% agreed that it was important for protecting patients and staff and was a professional ethical obligation, according to the abstract of Feemster's study.

Robert Rakita, MD, reviewed 5 years of experience with a flu vaccination mandate at Virginia Mason Medical Center in Seattle, the first hospital in the nation to adopt a mandate.

When the mandate was launched in 2005, the immunization rate rose to 97.6%, compared with 30% to 50% in previous years, Rakita reported. Since then the rate has stayed above 98%. Employees can be exempted for medical or religious reasons, but they are required to wear a mask during flu season.

Rakita noted that the Washington State Nurses Association opposed the mandate, and an arbitrator upheld their petition. But about 96% of nurses at Virginia Mason get immunized anyway, he said.

Andrew Pavia, MD, who moderated the press conference, said experience has shown that the highest flu vaccination rates achievable without a mandate are in the 80% range, and these have most commonly been achieved in children's hospitals. He is a pediatric infectious disease expert at the University of Utah.

Commenting on why organizations such as the IDSA are supporting mandates, he said, "If the best, most dedicated, resource-intensive programs only get you into the 80s, and most are only in the 50s, we need a better tool to increase immunization."

Children's risk factors for hospitalization
The report on risk factors for flu-related hospitalization in young children was presented by Nila Dharan, MD, of New York University in New York City. She and her colleagues analyzed data gathered by the Emerging Infections Program at 10 hospitals in nine states during the three flu seasons from 2005 to 2008.

They examined the cases of 290 children aged 6 to 59 months who were hospitalized with confirmed flu, along with 1,089 controls matched by age and zip code who were not hospitalized. They found that independent risk factors for hospitalization included living in a household where more than half the household members smoked, having a mother younger than 22 years, having a family income below the poverty line, and not being up-to-date on child immunizations.

The researchers also found that flu vaccination for any household member was protective for children who had not been vaccinated, but not for vaccinated children.

Neurologic complications in 2009 H1N1
Carol Glaser, MD, of the California Department of Public Health reported on a study of neurologic complications in pandemic H1N1 cases that were fatal or required intensive care unit (ICU) placement in California in 2009.

The researchers found 2,311 fatal or ICU H1N1 cases, of which 93 (4.0%) included primary neurologic manifestations, according to the study abstract. Thirty-six (39%) of the 93 patients had an underlying neurologic disorder. Encephalopathy and seizures were the most common neurologic complications. The median age of patients with neurologic manifestions was 7 years, compared with 38 years for all other fatal/ICU patients.

Race and ethnicity were similar for the neurologic cases overall and the other fatal/ICU cases, but Asians were overrepresented in the seizure group (40% versus 10%), the report says.

Glaser said the reason for the overrepresentation of Asians is unclear, but studies from Japan and other Eastern countries have been noting neurologic complications in flu cases for the past decade.

She said she wasn't sure how the California H1N1 findings compare with what's known about the rate of neurologic complications in seasonal flu, since flu is not a reportable disease and data have not been collected systematically.

Pavia commented that a study published recently in the Journal of Pediatric Neurology found that neurologic manifestations were more common in 2009 H1N1 than in seasonal flu cases.

Other reports presented today examined 2009 H1N1 vaccination in pregnant women. A study from the Marshfield Clinic in Wisconsin found that adverse effects of the vaccine were minimal, while a report from the Christiana Care Health System in Newark, Del., identified several demographic factors that predicted acceptance of the vaccine by pregnant women.