Protecting Vulnerable.

• Author: Engel, Mary
• Position: MEDICINE & HEALTH - Flu

"Not only should those with weakened immune systems get flu shots, their families and caregivers should, too."

FLU IS MISERABLE enough for someone who otherwise is healthy. It can be devastating for people whose immune systems have been weakened by cancer or treatment or both. Here are some things you should know--whether you are the person with cancer or anyone in that person's orbit. (Yes, family members, friends, coworkers, and care providers with healthy immune systems can take steps to protect those without.)

Flu is serious--always. Although there is no such thing as a good flu season, some are worse than others. Historically, the H3N2 strain causes more complications, especially in the elderly, young children, and people with chronic health conditions.

"H3N2 is notoriously related to severity," says Steve Pergam, medical director of Infection Prevention at Seattle Cancer Care Alliance, the Fred Hutchinson Cancer Research Center's clinical care partner. "We don't entirely understand the biology of why that is but, compared to other strains, H3N2 seasons tend to be worse."

In addition, vaccine effectiveness tends to be lower against H3N2 than against H1N1 and influenza B strains. Even in good years, vaccines seldom are more than 50%-60% effective because influenza mutates so rapidly. The Centers for Disease Control and Prevention recommends annual influenza vaccinations beginning at six months of age, as even a partially effective flu shot provides some protection--and can lessen flu's severity if you do get sick.

One of many stubborn myths about flu vaccination is that a shot can give you the flu. In fact, the opposite is true. Not only is some protection better than no protection, being vaccinated may shorten the course and lessen the severity of your illness should you get infected. "Even if it's not 100% effective at preventing you from getting the flu, getting a flu vaccine decreases the chances that you go on to develop severe illness," says Pergam. "It can help prevent major complications."

That can be huge. According to the CDC, about 80% to 85% of children who died from flu in past years were not vaccinated.

Pergam points out yet another reason to get a flu shot: multiple strains of influenza virus circulate in any given season, and each year's vaccine is designed to protect against the three to four variants that scientists believe will be most common. So, a vaccine that is not very protective against one strain may be more...