The ABCs of cold and flu season

Karen Miller and Howard Manly | 1/23/2013, 7:59 a.m.

People often confuse the flu with the common cold. That’s a mistake.

“They’re completely different viruses,” said Dr. Richard D. Zane, professor and chair of the Department of Emergency Medicine at the University of Colorado School of Medicine, formerly the vice chair of the Department of Emergency Medicine at Brigham and Women’s Hospital. “The symptoms can be similar, but those of the flu are more severe. The fever can be higher and of longer duration. Exhaustion, fatigue, and aches and pains are more pronounced with the flu.”

Influenza, more commonly referred to as the flu, is a contagious virus that attacks the respiratory system — nose, throat, bronchial tubes and lungs. Anyone is susceptible, but some people are at higher risk of developing serious complications. Small children, the elderly, those with weakened immune systems or certain chronic medical conditions can be hit hard by pneumonia and other infections.

These complications can be deadly.

Although flu-related deaths vary from year to year, according to the Centers for Disease Control and Prevention (CDC), as many as 48,000 succumbed during the 2003-2004 flu season. That’s more than the estimated number of deaths every year from breast cancer.

“It’s not an entity to be taken mildly,” said Dr. Nancy Norman, Medical Director of Integration at Massachusetts Behavioral Health Partnership, formerly the chief medical officer of the Boston Public Health Commission. “Some people have the attitude — I’m young, I’m healthy — and don’t pay attention to it. Yet some of these very people died of complications.”

There are three types of influenza virus — the As, Bs and Cs. Influenzas A and C can infect animals as well as humans, while Influenza B circulates among humans only. Type A is more serious and the cause of deadly worldwide pandemics, including H1N1.

But the flu virus is forever changing. It mutates, establishing a slight variation of its previous form.

It is this variation that causes problems when developing vaccinations against the disease. Seasonal flu vaccine typically contains two strains of A and one of B virus, but scientists can only estimate which types and subsets will circulate each year.

“It’s hard to be 100 percent correct,” said Zane. “But that’s not a reason to not get a vaccine. Even if wrong, the symptoms are much less severe.”

The CDC estimates the effectiveness at closer to 60 to 90 percent. Regardless, the vaccination helps reduce the risk and severity of the illness should it strike.

When asked if flu shots are necessary, Zane quickly responded, “Unequivocally yes. It protects you and prevents the virus from spreading.”

Flu viruses spread easily — usually through a sneeze or cough of an infected person. When a person with the flu sneezes, they are in effect launching the virus into the air — and into the vicinity of anyone around them.

Sometimes a person can become infected by touching something that harbors the flu virus — like a keyboard or doorknob — and then putting their hand to their face, allowing easy entry of the virus through their nose, mouth or eyes. Fortunately, the virus cannot live for extended lengths of times on non-living surfaces; they require a host, such as a person or animal, in order to survive.