What’s the difference between the “normal” flu shot and the new quadrivalent vaccine? We began hearing this question last flu season and as more people have become aware of a “new” kind of flu shot, we’re hearing it more and more. The answer is pretty simple. Tri means 3 and that’s the number of flu strains covered by the vaccine. Historically, manufacturers of the flu vaccine would choose the 2 main types of Influenza A anticipated to affect North America, H1N1 and H3N2. They would also try to predict which of the 2 major Influenza B viruses would be most prevalent during the upcoming flu season and would include protection against that one in their trivalent vaccine. So trivalent vaccines include protection against 2 types of Influenza A and 1 type of Influenza B. As you might have already guessed, quadrivalent vaccines include protection against the same 2 Influenza A strains but also include both major strains of Influenza B. In summary, the quadrivalent vaccine offers greater protection against the flu.
So, why would manufacturers even make the old flu vaccine anymore? That’s a pretty great question. The quadrivalent vaccines are just as safe as their trivalent predecessors because they are both incubated the exact same way. The downside is they cost a little more (about $10 more on average). My guess is that the vaccine manufacturers are likely giving us time to adjust to the change before they discontinue the trivalent vaccines altogether in favor of greater community protection against the flu.
The CDC is urging everyone 6 months of age and older to be vaccinated against the influenza. The are recommending the quadrivalent if it’s available but advising us not to wait for it. If the trivalent vaccine is available in your area, get the trivalent vaccine. It takes a few weeks for your body to produce adequate immunity to the flu. Being vaccinated now could mean the difference between a happy, healthy holiday season or spending your holidays in bed with a fever and body aches.
For more about the quadrivalent vaccine visit https://www.cdc.gov/flu/protect/vaccine/quadrivalent.htm