Influenza

What is it?

You know what the common symptoms of the flu are. It comes around right about the time that my tan fades and we start having more “girls nights in” than “girls nights out”. It starts with the “oh crap, I feel very, not good” which quickly turns into “oh crap, I feel like I’ve been hit by a truck”, along with the fever, aches, and runny nose. But what actually causes all the bad vibes? Well, there are four types of influenza virus A, B, C, and D, of which usually only A and B end up making you sick. They each have certain surface proteins that enable them to bind to your cells, and once they do your body holds nothing back in trying to shake them off. Your immune response is actually where most of your symptoms come from.

How does it change every year?

According to The CDC the influenza virus mutates each year by two methods: antigenic drift and shift. Antigenic drift is when there are small mutations in the genes that lead to changes in their surface proteins, hemagglutinin (HA) and neuraminidase (NA). These are what trigger an immune response in humans; so therefore, as they change over time the immune system’s memory cells won’t match up anymore. The second method is known as antigenic shift. A shift is an abrupt and major change in the influenza A virus that results in completely new HA and NA surface proteins on the virus. An example of a shift would be when an animal influenza strain gains the ability to infect humans. Usually when this happens, humans have no immunity to the radically new strain. Antigenic shifts have a more intense effect on humans due to the lack of immunity.

What is the effectiveness of this year’s vaccine?

The exact effectiveness of this year’s vaccine is not known right now as we are currently still in flu season, but according to The American Academy of Pediatrics the vaccine has been updated based on data from previous years to better match this season’s most virulent strains. In previous seasons, a decline in the effectiveness of the vaccine to influenza A(H3N2) viruses had been observed; and therefore, The World Health Organization updated their recommendation based on this information and the evidence of antigenic drift. Updates were made in the A(H1N1)pdm09 component as well as the A(H3N2) component for the Northern Hemisphere 2019-2020 influenza vaccine composition recommendation.

Regardless of just how effective the vaccine this, even a low effectiveness does not discredit the importance of receiving a vaccine. Even little immunity is better than no immunity at all. It has been proven that those who received the vaccine and still got the flu had signs and symptoms of less severity than those who did not receive a vaccine. So go get yo wife, yo kids, yo friends, and yoself vaccinated anyways.