It’s that time of year again. No, fellow duckaholics, I mean flu season. This 2009-2010 season should be interesting with all worries about the seasonal flu (influenza) and the Novel H1N1 (swine) flu.

Influenza A causes over 36,000 deaths in the United States a year. Two main variants (H1N1 and H3N2) have been recognized globally since 1977. Influenza A tends to give more respiratory symptoms with cough and shortness of breath. Influenza B is what we often associate with a runny nose and call the “common cold.”

In 2009, a new and genetically different variant from these appeared. It appears to be partly derived from a virus known to infect swine, and contains H1N1 markers. Swine flu is not new, but there is potential for more human illness because most humans do not have immunity to this novel combination. New viruses are formed during reproduction when mutations occur during replication. Many are similar enough to other viruses to which the body has already developed immunity because of previous exposure. Novel H1N1 Influenza A is the name given to “swine flu” because its markers are unique to most humans’ immune systems.

The most effective method of preventing influenza is the annual flu shot. I do not promote the FluMist or the nasal vaccine in my practice because it is a live vaccine and the recipient is actually contagious for about 10 to 14 days. The shot contains a partial virus—enough to create immunity without making you ill.

The flu shot does more than just prevent influenza. Ear infections in children, deaths related to hospitalization, diabetic complications and shorter durations of illness have all been shown to be reduced in people who have had the shot. The most common side effect is soreness at the injection site, lasting less than two days. Less often, fever, muscle aches and fatigue occur from the injection.

Flu shots cannot cause the flu! Many people blame the injection (which develops your immunity over a couple weeks) when they get the flu during that time. It’s coincidental, but not causal. A separate “swine flu” shot is being prepared and instructions will be published later this fall. iBi