Just yesterday, a friend engaged in casual conversation by asking if I was seeing the Flu yet in my office. “Only one confirmed case so far”, I told her. “Well, a few of my friends got the flu after getting the shot this year” she remarked. She anticipated my response – “You can’t get the flu from the flu vaccine!” Year after year, I hear the same comment- from friends, patient parents, acquaintances, the FOX news network (j). What is happening in these cases? Are people really suffering a side effect of the vaccine itself? The influenza vaccine, like all other vaccines, does incite an antibody response. In fact, its effectiveness lies in its ability to stimulate the immune system to produce disease fighting agents that well, may make you feel a little under the weather for a day or two. Low grade fevers, a few muscle aches and some fatigue are normal and fleeting, and honestly a heck of a lot more tolerable than influenza. But what about the people who develop an actual illness post vaccination—an upper respiratory illness characterized by a sore throat, cough, congestion and a fever that runs a typical cold course? Did the flu vaccine precipitate this illness?

Based on how a vaccine works; how it grabs the attention of the immune system and encourages specific antibody production, it seems quite possible that despite its grand complexity, the immune system turns its full attention away from the current enemy to prepare for a future invader. Thus, a common cold develops in a person that was fighting off the illness quite well before being immunized. This theory drives my decision to hold vaccines when one of my patients is acutely ill. It is not that I don’t think they can handle the vaccine if ill, but it may complicate the picture. They will probably feel worse for a day or two after vaccination, which may then cloud parental and even physician judgment with regard to determining whether the illness itself is progressing or is simply a transient effect of vaccination. We can still watch and wait regardless, but when your own child is up all night and they’ve been fighting a cold for a week already and now have a new fever, decreased appetite and increased fussiness… watching and waiting is hard. Unless absolutely necessary, I want to hold off on antibiotics, as do most parents, so if we can give them a little more time to adequately clear their infection before getting vaccines, I am absolutely in favor of it.

What are the actual risks of the flu vaccine as it relates to kids? The CDC states soreness, redness, or swelling at the site of injection, fainting (mainly among adolescents), headache, muscle aches, fever, and nausea. If these problems occur, they usually begin soon after the shot and last 1 to 2 days. Anaphylaxis to a vaccine is exceedingly rare, but if it does happen, it generally occurs within 1-2 minutes of administration, when you are still in your doctor’s office and surrounded by persons equipped to handle such an emergency. A very remote side effect, known as Guillain-Barre has been found to occur in 1-2 people per MILLION vaccinated against the flu. Guillain-Barre causes a progressive weakness and paralysis as the immune system misfires and attacks a person’s own nervous system. The exact etiology of Guillain-Barre is unknown, but can follow random illness or rarely vaccination. I have had a patient develop Guillain-Barre in the last year as a post-viral response. I sent him to Children’s Medical Center upon presentation, where he was effectively treated via IVIG (healthy donor immunoglobulins given via an IV that displace the attacking cells from the nervous system). He now runs full speed down the hall when he comes in to see me! He grins, speaks, and high-fives as effortlessly as he runs.

There is an additional risk worth noting; an increased risk of a febrile seizure (or seizure with fever) in kids who receive the Prevnar (or pneumococcal) vaccine at the same time as the influenza vaccine. Febrile seizures occur quite randomly with fever viruses in the pediatric population, generally between the ages of 6mos and 6years, with no associated long-term complications. But, you may ask yourself – does it make sense to get these two vaccines together? If it is flu season and time for your child’s booster Prevnar vaccine, then the answer is a simple yes. The killer in an influenza infection is often not the flu in and of itself, but rather the superinfection; the secondary pneumonia often caused by invasive streptococcus bacteria. This is the combination that overcomes us. The immune system is busy eradicating the flu virus when the stealthy pneumococcal bacteria slip into the respiratory tree and incite a war. This intruder is often recognized too late by our complex defense system, and a delay in response can prove fatal.

Are the risks of the flu mist any different than those associated with the injectable form? The CDC provides the following list of potential side effects – runny nose, fever, headache, sore throat, nausea and vomiting. Runny nose is perhaps the most common and is very short-lived. The mist is the preferred coverage for kids aged 2-8yrs, per data that shows greater efficacy at prevention in this age group when compared to the shot. But how effective is the flu vaccine in general at preventing the flu? Most studies estimate about a 60% reduction in flu illness among vaccinated persons, although this number does vary some from year to year. More importantly, a recent study showed that the flu vaccine reduced children’s risk of flu-related pediatric intensive care unit (PICU) admissions by 74% during flu seasons from 2010-2012. This fact alone is reason enough to vaccinate your kids this season. The greatest truth to the flu vaccine that I witness on a day to day basis, is that if you’ve been vaccinated but still contract the flu, you are likely to be significantly less sick than your unvaccinated peers with the exact same strain of the illness. Two years ago, I contracted Flu B. I didn’t feel great for about a day, required no medication and had no real loss of work days or parenting days! My entire family had been vaccinated, as had I, and no one else in my family contracted the illness. My viral load was likely much lower, and thus I was less contagious and not nearly as sick as I might have been in the absence of vaccination.

I know it is hard to do anything that may make you feel off for a day or two, but being laid out for a week at best seems a much worse alternative. Building a robust immune response to influenza stems from the introduction of an attenuated form of the virus to our relatively naïve system, so that when we face the real thing, which undoubtedly at some point we will, we can fight the flu in full armor.

 

http://www.cdc.gov/flu/about/qa/vaccineeffect.htm

Belshe RB, Mendelman PM, Treanor, et al. The efficacy of live attenuated, cold-adapted, trivalent, intranasal influenza virus vaccine in children. N Engl J Med. 1998; 338(20):1405-12.

Ferdinands JM, Olsho LEW, Agan AA, et al. Effectiveness of influenza vaccine against life-threatening RT-PCR-confirmed influenza illness in US children, 2010-2012. J Infect Dis. 2014; 210(5):674-683.