The USA is experiencing the earliest flu season in nearly a decade, says the Centers for Disease Control and Prevention (CDC).

Cases of likely flu have increased in five states in the south of the country. A virulent strain (H3N2 viruses) - one that makes people sicker - appears to be dominating, officials say. Elderly individuals are particularly at risk of severe symptoms and complications.

CDC Director, Thomas Frieden, said: "It looks like it's shaping up to be a bad flu season, but only time will tell."

Dr. Frieden added that the country appears to have prepared well for the flu season this year. Over one third of US citizens have received the flu shot. Authorities say that the vaccine protects against flu virus strains that are currently infecting people.

The following states are reporting particularly high rates of influenza:
  • Texas
  • Alabama
  • Mississippi
  • Louisiana
  • Tennessee
Forty-eight states, as well as Puerto Rico, have reported confirmed cases of influenza. The number of samples that are coming back from the lab with positive results is growing rapidly, the CDC wrote in a communiqué today.

The CDC wrote: "Influenza-like-illness (ILI) activity levels in parts of the country are already higher than all of last season."

Experts are not sure why influenza has appeared so early this year. However, hospitalizations of patients with flu are rising earlier than they usually do. Two children have died from flu-related illnesses.

The last time the flu season started this early was during the 2003/2004 season. The flu strain then was the same as the one that is circulating now. In that year, nearly ten years ago, there were exceptionally high numbers of flu-related hospitalizations and deaths among children and seniors.

Health authorities getting better at predicting upcoming flu strains

The vaccines used in 2003 did not match the circulating strains later on in the year as well as those administered this year, the CDC informed. With new technology, governments around the world are getting better at predicting which flu strains will circulate during the upcoming influenza season.

There are also more vaccines available today than there were nine years ago.

A significantly higher percentage of people, including health care workers and pregnant women, are receiving flu vaccines this year compared to 2003/2004. An article published in CMAJ (Canadian Medical Association Journal said that all health care workers should be made to have the flu jab, in order to protect the health of patients.

The CDC says that approximately 112 million Americans have been vaccinated so far this year.

Dr. Melinda Wharton, Acting Director of CDC's National Center for Immunization and Respiratory Diseases, said "Increasing flu activity should be a wake-up call. For anyone who has put off vaccination: It's time to get your flu vaccine now."

FluView wrote that influenza activity is highest in the south-central and southeast of the country. However, all signs indicate that the rest of the country will soon follow suit.

Influenza can become a serious public health issue

Influenza can cause up to 200,000 hospitalizations in one season, and may be the cause of death of up to 49,000 people, according to the CDC.

Vaccination is the best way to protect individuals and whole populations against influenza. A vaccine's effectiveness depends on how closely its virus strains match those in circulation, as well as the patient's age.

Public health authorities in the USA say that every American aged at least six months should be vaccinated against flu. Vaccines are particularly important for people at high risk of complications, including: Up to 80% of hospitalized patients over the last few years had long-term health conditions, as did over half of all hospitalized kids.

Written by Christian Nordqvist