Dr. Jacqueline Gerhart: How Good Is the Flu Vaccine This Year?
Madison, Wisconsin - UW Health Family Medicine physician Jacqueline Gerhart writes a column that appears Tuesdays on madison.com and in the Wisconsin State Journal. Columns are re-published here with permission.
Dear Dr. Gerhart: How good is the flu vaccine this year?
Dear Reader: Each year, we don't know exactly how "good" the vaccine is until the flu season is over.
The flu vaccine protects against illnesses caused by three influenza viruses. Last year, this resulted in about 52 percent "vaccine effectiveness."
At first you might think that isn't very good, but if you compare that to people who do not get the flu vaccine, where "effectiveness" is 0 percent, then getting the vaccine is quite helpful.
To predict how this year's flu season and flu vaccine might be, we need to look at last year's trends, and study preliminary data from this year. According to the Centers for Disease Control (CDC), the 2011-12 flu season was actually quite mild.
Usually, visits to the doctor for influenza-like illnesses start to rise in late December, peak in February and then drop. And usually, there is about a 13-week period where flu-like illnesses are among the main reasons people visit the doctor.
However, in the 2011-12 winter season, influenza-like illnesses remained low through February and experienced a small peak in March. And there was only one week where flu-like illnesses were significantly higher than usual.
So why was last year a success? First off, the flu vaccine last year was a "good match." Also, I would like to think that health care providers are doing a good job of educating the public on what symptoms are significant enough to see the doctor, thus cutting down on visits for the common cold. I also hope people are getting wiser about hand sanitation, eating healthy and exercising - all of which help us to stay healthy and influenza-free.
The bad effects (morbidity and mortality) from the flu are also decreasing. Last season there were 34 pediatric deaths from the flu, which is the lowest number ever recorded. The number of hospitalizations from flu was also down, with about 30 out of every 100,000 patients aged 65 and older being hospitalized for flu.
What data do we have for this year? To answer this, I turned to Jon Temte, MD, who is chair of the U.S. Advisory Committee on Immunization Practices. As of this week, Wisconsin continues to have extremely low influenza activity. Our state also has reasonably low numbers of visits to the doctor for respiratory illnesses.
Last week, 11.4 percent of all primary care visits came with respiratory illnesses, but only 0.7 percent of these fit the parameters for influenza-like illness. In order to qualify as a flu-like illness, the patient must have a fever greater than 100 degrees F, and have either a cough or sore throat.
Of the 0.7 percent that fit these parameters, only a few tested positive for influenza. Currently, the majority of respiratory infections that we've seen have been caused by rhinoviruses and parainfluenza - not influenza itself.
Based on available data, there appears to be an excellent match between this season's influenza vaccine and the circulating strains of influenza. Therefore, we are recommending that all patients, starting at age 6 months, receive the flu vaccine. We also ask that all people in health care settings get the vaccine to help prevent the spread to other patients and to the community.
To get your flu vaccine, visit your primary care office, your county's public health office, or a local pharmacy.
This column provides general health information and is not specific advice intended for any particular individual(s). It is not a professional medical opinion or a diagnosis. Always consult your personal health care provider about your concerns. No ongoing relationship of any sort (including but not limited to any form of professional relationship) is implied or offered by Dr. Gerhart to people submitting questions.
Date Published: 11/27/2012