The World Health Organization (WHO) said today it is unable to assign a severity scale to the influenza A (H1N1) epidemic for the reason that disease characteristics and responses of countries vary.
Dr. Sylvie Briand, with the WHO Global Influenza Programme, spoke today at a media briefing in Geneva. As of 1:00 am EDT, 33 countries had reported 5728 confirmed cases of influenza A (H1N1) infection.
According to Dr. Briand, the WHO pandemic alert level phases are mainly based on the transmission of the virus and its geographical spread, while "the severity itself is assessed by other means." Currently, the pandemic alert level has remained at level 5 out of 6, indicating community-based outbreaks in a single WHO region.
The severity of a potential pandemic is based on 3 factors: "the [characteristics of the] virus, the vulnerability of the population, and the intervention we can put in place to reduce the impact of severe disease," Dr. Briand said.
Assessing severity is important for helping countries determine their response to an outbreak, but at a global level, a severity index is "not very helpful" because "severity will vary from place to place," she said.
Dr. Briand pointed out that while wealthier countries may have the resources to mount a more effective response to an outbreak, some developing parts of the world such as West Africa are already used to coping with epidemics and may be at an advantage due to having healthcare systems in place. This is referred to as the "resilience" of a country, she said.
Dr. Briand also emphasized that oseltamivir and zanamivir are effective against this novel H1N1 strain, which is in contrast to the seasonal influenza strain, which is resistant to these antiviral drugs.
News reports are circulating regarding a claim by an eminent Australian influenza researcher that human error may have been involved in creating this strain. Adrian Gibbs, 75, said in an interview that he intends to publish a report suggesting the new strain may have accidentally evolved in eggs that scientists use to grow viruses and drugmakers use to make vaccines.
WHO spokesperson Gregory Hartl said the WHO is looking into evidence regarding these claims, but "it is way too soon to say anything." He added that the WHO's main task is to assess the current risk level and to "help member states to be prepared to respond."
The US Centers for Disease Control and Prevention (CDC) today is reporting 3009 laboratory-confirmed cases in 44 states and Washington, DC.
Yesterday the CDC issued a dispatch in the Morbidity and Mortality Weekly Report on novel influenza A (H1N1) virus infections in pregnant women. As of May 10, 20 probable or confirmed cases had been reported in pregnant women. Of the women, 3 have been hospitalized and 1 woman died.
The CDC is recommending that pregnant women with confirmed, probable, or suspected novel influenza A (H1N1) virus infection should receive antiviral treatment for 5 days.
Interim guidance on issues specific to pregnant women and the novel influenza A (H1N1) virus is available at http://www.cdc.gov/h1n1flu/clinician_pregnant.htm.