Everything You Need to Know About The Flu

Last year, an estimated 80,000 Americans died from flu-related illness, the highest number of deaths in at least four decades, according to the Centers for Disease Control and Prevention. Experts are advising the public to take extra precaution this season and get their flu shot early.  

Terrence Stull, MD, a professor at the University of Arizona College of Medicine – Phoenix and director of Phoenix Children’s Hospital Research Institute, discusses this year’s flu season.

Why was last year’s influenza virus season so bad?

There are several variables that determine the severity of influenza season. It’s important to know that influenza viruses are not identical and therefore, the genes in those viruses are different amongst various strains. Those genes determine how contagious the viruses are. The genes also determine whether or not the influenza virus will cause a minimal or very severe disease in the host. There are a lot of complexities we don’t understand about the host, but we do know that disease severity depends on which influenza viruses a person has experienced in the past because sometimes you can acquire partial immunity from a past infection. The worst epidemics are when you have a highly contagious influenza virus that causes severe disease and a population who has not experienced any influenza viruses like this and therefore does not have the protected immunity.

Can influenza virus ever be eradicated?

The influenza virus probably will not be eradicated. For example, we have eradicated smallpox, and one of the important reasons we were able to eradicate smallpox from all human populations was because smallpox only exists in humans. So when we eradicated smallpox from humans that means it’s no longer present in nature. The influenza virus infects a lot of different hosts such as birds and pigs. Even if we momentarily eliminated the influenza virus in humans, which is already very difficult, we would still be at risk of getting the virus from animals.

How are vaccines made before we even get the flu?

There are a lot of steps in creating vaccines, which makes it imprecise. One step is to find the likely influenza virus that is coming to the U.S. Experts at the CDC examine influenza that is isolated around the world. All major countries participate in isolating the influenza virus and sharing those strains and the sequence of the genomes of those strains. There is an exchange of information amongst scientists worldwide about which influenza viruses are prevalent in different countries. Experts at the CDC examine those influenza viruses and then have methods to predict which ones are going to be the predominant influenza viruses in the U.S. Those predictions are good, but they are not perfect.

After the prediction is made, then the influenza vaccine is manufactured. Most influenza vaccine is made from virus grown in chicken eggs. This is a very old and a very established methodology, which means it’s very reliable, but it is relatively slow.

When is the most effective month to get the flu shot?

Personally, when the influenza vaccine comes to market, I try to be the first in line. The influenza vaccine usually becomes available in September or October. I recommend getting the vaccine as soon as possible, at least by the end of October.

What are the best ways to prevent flu besides the flu shot?

The disease “flu” is caused by many different viruses. The influenza shot does not protect against other viruses and is not 100 percent effective against influenza viruses. I recommend getting the flu shot to be protected against the strains it covers, but I also recommend taking alternative precautions. The flu is often transmitted by hand, so it’s important to wash your hands before eating and before touching your face. Remember to wash your hands often. Cover your mouth when sneezing and coughing to reduce transmission and don’t be around people who have symptoms of the flu. If you are sick and have a respiratory illness, stay away from others to make sure it’s not transmitted.

How easy is it to catch the influenza virus?

It’s definitely contagious. Some strains are more contagious than others, but it’s definitely a contagious virus that warrants the attention of getting the influenza vaccine. Tens of thousands of people die every year in the U.S. because of influenza virus. We need to pay attention to that and do everything we can to prevent transmission and the disease in ourselves.