Public health officials say it is too early to determine the severity of this year's flu season. But the U.S. Centers for Disease Control's Influenza Division reports the infection rate is on the rise in virtually every state.
Epidemiologists in the United States agree that more Americans who took flu shots in the fall will contract the disease, despite their inoculations. That is because the vaccine, which was formulated last year by the World Health Organization (WHO) does not protect against many flu strains prevalent this year in the United States.
Dr. Daniel Derman says the WHO vaccine, which is distributed around the world, protects against only three strains of influenza virus.
"This year, the viruses that are coming around America are not covered in the top three that are in the vaccine," said Derman, a doctor with Northwestern Memorial Hospital.
Also, there are new concerns about Tamiflu, the most used drug to treat influenza. Several states, including Illinois, have detected a Tamiflu-resistant strain of the flu virus.
"The flu bugs this year, about 4 percent are resistant to Tamiflu. In any particular year, over the last five years, it's usually about 1 percent," Derman said.
But, the doctor also said, in cases where Tamiflu is ineffective, other anti-viral drugs are effective. Derman said it is important that doctors combine therapies when treating chronically ill and older patients.
"Every year, about 36,000 people will die in America because of the flu; it's the compromised patients with chronic disease and the elderly," said Derman.
The estimate is that flu shots taken in advance of this season will be about 40 percent effective. Doctors stress that is still much better than no vaccination at all.
Dr. Derman said when vaccinated people do contract the disease, it is usually less severe than if they had not had a flu shot.