June 18, 2009 -- About 7% of the population in areas highly affected by H1N1 swine flu report influenza-like symptoms, a spokesperson for the CDC said during a news briefing today.
Daniel Jernigan, MD, MPH, deputy director of the Influenza Division at the National Center for Immunization and Respiratory Diseases at the CDC, provided an update about the H1N1 pandemic, stating that the U.S. will likely continue to have flu activity through this summer and probably until the start of the fall flu season.
Jernigan said about 89% of flu cases confirmed by the CDC are of the H1N1 strain. The number of cases varies significantly from region to region, with Northeastern states continuing to see the highest numbers, especially New York and Massachusetts.
The number of lab-confirmed cases in the U.S. is now estimated at more than 17,800, which includes about 1,600 hospitalizations and 44 deaths.
"These numbers are likely an underestimate of the number of cases that are out there," Jernigan said. "The amount of disease in the areas that are having activity with H1N1 is perhaps around 7% of the population reporting symptoms due to influenza-like illness."
Antivirals -- such as Tamiflu and Relenza -- still appear to be effective against H1N1. "We are recommending that [antivirals] be used in high-risk patients that are sick and also in those that are being hospitalized," he said.
He added that asthma, diabetes, and heart disease are the most predominant underlying conditions in hospitalized patients.
"About 40% or so [of hospitalized patients] have some kind of underlying disease," Jernigan said during the call. "The most predominant [underlying condition] is asthma, [with] the second being diabetes." He added that immunocompromised status -- either through cancer chemotherapy or immunocompromising conditions -- is present in about 13% of the patients, as is chronic underlying heart disease.
Swine Flu Among Health Care Providers
Officials also discussed H1N1 infection among health care personnel. Michael Bell, MD, associate director for infection control in the Division of Healthcare and Quality Promotion of the CDC's National Center for Preparedness, Detection, and Control of Infectious Diseases, discussed a report in the June 19 issue of the CDC's Morbidity and Mortality Weekly Report.
The report, which describes swine flu cases among health care workers through May 13, includes detailed information for about 26 patients. None of the patients with the H1N1 swine flu virus died or required intensive care during hospitalization, Bell said. Half of them had exposure within the general community or from unknown causes, and the remaining half probably contracted the disease within the health care setting.
According to the report, "most of the probable or possible patient-to-[health care provider] transmissions ... occurred in situations where the use of [personal protective equipment] was not in accordance with CDC recommendations."
Bell pointed out that they are beginning to see a pattern of transmission between health care workers in some of these additional clusters, "which is also concerning because it gets to the issue of people showing up for work sick." He added that health care workers should stay home if they are sick and that health care facilities need to have appropriate sick leave policies.
The report does note that health care personnel do not appear to be "overrepresented among reported cases of persons infected with novel influenza A (H1N1) virus in the United States."
There is no routine recommendation for health care workers to receive antiviral medication, Bell said. "Probably the most important thing is that infectious patients be identified at the front door."
Current recommendations to prevent the spread of swine flu include using a single patient room for infected individuals and having infectious patients cover their cough. Health care personnel are advised to use respirators, gloves, gowns, and eye protection while they are in patients' rooms. In addition, careful attention to hand hygiene is also recommended.