Influenza Update 2014/2015
As I grow older, I find that I mark my time more so by passing seasons. Living in Michigan it's easy - the first flowers nudging up through the snow, the first day I am able to wear shorts, the first tree with colored leaves and the first snow. I also mark the football season with my team's first game as well as my kids' first day of school. These events add to the richness of life.
This week, however, marked an unsavory season that I experience each year as a doctor. This season, I usually mark with the arrival of a letter from my local health department announcing that flu season has begun with crowded emergency rooms and calls to my office looking for help.
The media usually cashes in on this fear if there is any story to be told. The debate usually ensues about whether or not to get the flu vaccine. And if exposure or symptoms arise, patients ask and doctors deliberate on whether a medicine like Tamiflu will offer any benefit.
This blog will update our current understanding of this year's influenza scourge.
Is This Year Worse Than Others?
The quick answer to this question is that this year will likely be a worse-than-average year in regards to influenza numbers and severity.
Formulating the influenza vaccine is a calculated guess each year. As a virus, influenza is prone to, and even expected to mutate somewhat each year. Watching yearly trends and momentum gives researchers a best guess scenario as to the formulation of the vaccine to combat the most likely strain of the coming year's influenza. Occasionally, however, a more significant mutation takes place.
This is known as a genetic drift.
Early indications based on many of the samples isolated from early in the season, show that such a drift has taken place and developed a more virulent strain known as H3N2. This strain is not part of the make-up of this year's influenza vaccine as it was discovered after the formulation was already in production. (1)
Will my flu vaccine protect me?
The influenza vaccine protects against three or four strains of the influenza virus. The vaccine stimulates the body to produce antibodies against those three or four strains. It has been shown, however, that these antibodies can sometimes help to provide protection against different, yet related influenza strains.
Although this year's vaccine may not be an ideal match, it is still better than nothing in the hopes that it will yield lower rates of infection or reduced severity of illness. In addition, those expected strains are out their too and may increase in prevalence later in the flu season.
It is not too late to get the influenza vaccine to provide protection during this flu season. While it does take a few weeks for the body to produce immunity, we will still be at the height of the influenza season during this time. Vaccination is especially important for those more susceptible to influenza: children, elderly and illness that increase susceptibility such as asthma or a compromised immune system.
If I am exposed, should I take Tamiflu?
Tamiflu and it's related medicine Relenza are anti-viral medications called neuraminidase inhibitors used in combatting influenza. Results are a bit disappointing in satisfying the hopes of an exposed or ill patient in helping them eradicate the influenza that they are battling.
In general, using these medications for those actively infected can only garner benefit if given within 48 hour of symptom onset. Efficacy in trials has shown that the medications will yield small benefits in reducing symptoms and knock an average of one-half day off the duration of illness. Further, the prevention of hospitalization and severe complications when these medications are given really panned out. (2)
One recent meta analysis revealed that these medications can offer benefit to asymptomatic household contacts when a documented case is present. This benefit did not extend outside the household. (3) Further, the risks of the medication such as vomiting/diarrhea, dizziness and headache may outweigh the benefits.
In general, if considering use of Tamiflu or Relenza, weigh the benefits and risks. Benefits may be weighed by susceptibility to the influenza such as age category, asthma or a compromised immune system. It may also be weighed by a close household contact with documented influenza in the absence of current symptoms.
If you develop symptoms of influenza (severe muscle aches, fever, cough and mucous production), rest, get plenty of fluids and treat the discomfort with an anti-inflammatory or acetaminophen. Seeing a healthcare provider will likely yield this advice and is probably not needed, especially with the potential for infecting others as you venture out into public. Watch closely, however, for the feared complication of pneumonia. Pneumonia is usually heralded as a persistence of symptoms for days with maybe even some improvement and then a sudden worsening with cough, shortness of breath and fever. If pneumonia is suspected, seek medical attention.