Although any existing or emerging virus can become a pandemic, the H5N1 outbreak that has infected 66 Americans and more than 900 dairy herds is "poorly suited for pandemic potential," according to Shira Doron, MD.
Dr. Doron, chief infection control officer of Boston-based Tufts Medical Center, said the avian flu virus would first need to undergo several mutations to better bind to human airway cells before it could lead to human-to-human transmission and eventual pandemic status.
One of the 66 human cases has died, officials said Jan. 6. The older Louisiana resident was hospitalized for severe illness — a first in the U.S. for bird flu — after being exposed to a non-commercial backyard flock and wild birds. Former outbreaks have shown about a 50% mortality rate, and although one of 66 is nowhere near that figure, there is definitely an undercount of cases, Dr. Doron said.
In August, the CDC said the outbreak "indicates the virus has a moderate future potential pandemic risk when compared to other Influenza A viruses," and that the current risk to the public is low.
On Jan. 10, the Infectious Diseases Society of America held a press briefing with Dr. Doron and Julio Figueroa, II, MD, infectious diseases chief at LSU Health New Orleans, to discuss the current state of the H5N1 outbreak.
Dr. Figueroa also predicted a low chance of a bird flu pandemic because the sequence that was done for the Louisiana patient was very close to the vaccine strains available for manufacturers. The U.S. is holding back on vaccination efforts, though.
There are several reasons why there is not a federal vaccine rollout, according to Dr. Doron. Infections in farm workers have been universally mild, and an inoculation effort would face language barriers, noncompliance amid an era of vaccine skepticism, and several individuals with undocumented status, who might hesitate to seek medical help even when presenting symptoms.
One of the pitfalls to the nation's response has been poor coordination among authorities for human public health, animal public health and wildlife.
"It is a very difficult undertaking to coordinate between the various agencies that are responsible for this outbreak response," Dr. Figueroa said. "This is an unprecedented type of outbreak that involves agriculture, wild animals and humans."
As of Jan. 7, the CDC has confirmed avian flu cases in 133 million poultry, 919 dairy cow herds and nearly 11,000 birds.