The Flu: Fall’s Feared Foe

Dr. Travis King, Assistant Professor specializing in Infectious Diseases Pharmacotherapy

It’s that time of year again! The time of the year when everyone gathers in The Grove to celebrate a Rebel win (….and the occasional loss), when families converge in mass for holiday cheer, and when the influenza (“flu”) virus spreads silently in the background like raging wildfire (*cue scary images from Contagion*). The seasonal flu virus plagues us each year beginning as early as August or September in some areas before taking flight in October and officially wrapping up in April or May (Official 2012-2013 Influenza Season: September 30, 2012–May 18, 2013). It is a leading cause of hospitalization, healthcare resource utilization, and even death in the United States, particularly among the young and the elderly. Treatment for the influenza virus is largely aimed at shortening the course of the disease. These antiviral agents, like Tamiflu® (oseltamivir), are best taken as soon as symptoms appear, ideally within 48 hours. Unfortunately, most individuals do not seek healthcare until it’s too late, minimizing the benefit that these medications may provide. Newer antiviral medications are available but suffer from the same early initiation requirement as Tamiflu®.

So, what’s a person to do? Vaccination!

Everyone knows the saying “An ounce of prevention is worth a pound of cure”. The unacceptable aspect about influenza-related complications is that most of them are preventable!! So each year, as the flu season approaches, the Centers for Disease Control (CDC) advocates for wide-scale vaccination of the United States population. Their official recommendation reads: Everyone older than 6 months of age should receive an annual influenza vaccination.

There are two major exceptions to this rule: 1) If you have a serious egg allergy or have had an allergic reaction to a previous year’s flu vaccine, you should avoid receiving any egg-based flu vaccines unless advised otherwise by your healthcare provider. 2) If you have ever experienced Guillain-Barré Syndrome (a rare paralytic disorder) after receiving a flu vaccine, it is advised that you seek the opinion of your healthcare provider prior to any future vaccinations.

Easy enough, huh! …… But why every year?!

Unfortunately, the influenza virus – not unlike all the other microbes on this planet that want to make us their lunch – is smart .It just wants to survive. So, as the virus traverses the fall, winter, and spring months, it changes itself to evade our body’s immune system – process called “antigenic drift”. This means that this year’s virus may not look like next year’s virus, and so on. To help combat this, the flu vaccine is reformulated each year, which means that we need re-vaccination each year. Using statistics from the previous year, known viral composition, and other epidemiological characteristics, the World Health Organization and the CDC create a combination of 3 or 4 viral components to comprise the season’s vaccine. These typically are made up of two Influenza Type A strains (including the H1N1 “swine flu”) and a Type B strain. These 3-virus vaccines are called “trivalent”. Newer vaccines available for the first time during the 2013-2014 season have been formulated to contain 4 different viral types: two of Type A and two of Type B (called “quadrivalent”).

Now, the next obvious question is: Does the vaccine even work?

It does! However, much like any medicine, individuals will respond differently to the vaccine. Vaccine effectiveness rates for the seasonal influenza vaccine teeter around the 60-70% range. This means that 60-70% of everyone vaccinated will remain flu-free during that particular season. Each year there is a subset of people who receive the vaccine and come down with the flu or a flu-like illness. There may be several explanations for this: 1) They didn’t develop a strong enough immunity from the vaccine (maybe they needed a higher dose) 2) They were infected by a strain not contained in the vaccine 3) They were infected with a virus other than influenza, and/or 4) they were exposed before immunity fully developed. While this by no means a comprehensive list, it does provide some of the more common scenarios.

One major point should be made regarding the flu vaccine, particularly in more at-risk populations (children and elderly individuals). Even in those patients who received the vaccine and who developed an influenza infection, death rates and hospitalizations related to the flu are significantly reduced compared to people who did not get the vaccination. This means that even if you catch the flu, by getting the vaccine, you are much less likely to suffer from flu-related complications compared to someone who did not get vaccinated.

The take-home point here is: Go get vaccinated!!

There are a couple of “myths” surrounding the influenza vaccine that are worth debunking.

1. You cannot catch the flu from the vaccine: The vaccine is inactivated. This means that there is nothing living in the vaccine – no live viruses at all. This means that nothing is present in the vaccine that can facilitate the establishment of a new infection. However, the vaccine does take 2-4 weeks to fully work. So, if you are exposed to the virus before your immune system has time to respond to the vaccine, it is possible that you may develop a flu infection. But, trust me…it wasn’t the vaccine. Things you may feel after getting the flu: Sore arm, low-grade fever, aches, a hankering for a lollipop, and a sense of pride resulting from the awesome Superman band-aid you receive.

2.There’s mercury in them there vaccines: This one is partially true. Some vaccines are batch-produced in preparation for the flu season. These “multi-dose” vials do contain the mercury-based preservative “thimerosal”. These preservatives are quite valuable, as they keep bacteria and fungi from growing in the vaccines while they await use at pharmacies, hospitals, and doctor’s offices. However, vaccines are also made as pre-made syringes. These “single-use” vaccines do not contain “thimerosal”. So, if you find mercury concerning, then the “single-dose” is the vaccine for you! Even more, starting in 2001, vaccines marketed for children are formulated to be thimerosal/mercury-free. Despite this, autism rates have not declined, indicating that the recent trends in autism are highly unlikely to be linked to vaccine exposure.

I hope that this extended, hopefully informative commentary has provided you with some perspective on the yearly flu vaccine, as well as instilled a desire to protect yourself and your family by getting a vaccination ASAP (The flu is here!!). If you’d like to continue reading on this topic, want more information, or just want to spend a weekday/weekend reading some science-y stuff, visit the CDC Influenza Website (http://www.cdc.gov/flu/). This portal of information is geared toward the general public and healthcare professionals alike, and provides a wealth of information for all.

Cheers and Hotty Toddy!

—Dr. Travis King, Assistant Professor specializing in Infectious Diseases Pharmacotherapy within the Department of Pharmacy Practice at the University of Mississippi School of Pharmacy.