2018 marks the 100th anniversary of the 1918 influenza pandemic, known more infamously as the “Spanish flu.” That pandemic killed 675,000 Americans and more than 50 million people globally. Since then, efforts to improve flu preparedness have changed significantly. Yet, flu still affects more than 3 million people in the US every year and it is still deadly.
Last flu season, more than 80,000 people died, according to the Centers for Disease Control and Prevention. Last year’s flu season was the most severe in decades, according to federal health officials.
Benjamin Lee, MD, is a pediatric infectious diseases physician at the UVM Children’s Hospital. He is also a researcher at the Vaccine Testing Center at the University of Vermont. He talks about what makes the flu deadly, why the flu vaccine is important, and how to stay healthy.
What does influenza do to the body and why is it deadly?
Lee: Influenza is a respiratory virus and a significant cause of acute respiratory illness. In temperate climates, the flu season occurs in the winter months. High fever, cough, headache, sore throat and severe body aches are the most typical symptoms.
It’s deadly for a number of different reasons. First, there are a number of severe complications that can result from an influenza infection, the most feared of which is pneumonia, which isinfection and inflammation within the lungs. The virus itself can cause pneumonia, but it’s also now well-recognized that people who have the flu are at much higher risk for getting a secondary bacterial pneumonia.
Finally, a number of underlying medical conditions may predispose someone to a more severe illness and difficulty fighting off the infection. So, for any number of reasons, it can be a very deadly infection in certain populations.
What’s the difference between a cold and the flu?
Lee: The most common difference is that the flu tends to be much more severe and tends to have a much more rapid onset. Fever is usually present and the symptoms come on very suddenly. The classic description of feeling like you’ve been hit by a truck is very fitting for influenza.
The common cold tends to be a bit more gradual. You may feel a little under the weather and then the next day a little bit worse, but the onset usually is not as rapid and the severity of the symptoms are usually not as intense. Fevers are less common with a cold, at least in adults. The symptoms generally tend to be upper respiratory symptoms, so nasal congestion, runny nose, sneezing, a bit of cough, et cetera. The most severe symptoms we generally tend to see with the flu.
Now, certainly there can be a little bit of overlap, but if you feel like you’ve been hit by a truck and you have a high fever and cough during the winter time, most likely that’s the flu.
How quickly does the flu spread?
Lee: During the proper season, it can spread very rapidly, especially in areas where there are a lot of close contacts, such as in schools or other crowded settings.
Flu generally spreads person-to-person via respiratory droplets. Coughing and sneezing expel respiratory secretions and direct contact with these secretions is how the next person gets infected. Simple precautions make a big difference: using proper respiratory etiquette, like sneezing or coughing into your elbow or shoulder and washing hands frequently can be very simple yet effective ways to help prevent the spread of flu. Staying home when you are sick with the flu is always a good idea to prevent transmission.
In addition, respiratory droplets left on surfaces are a vehicle for transmission. So, if somebody sneezes into their hand and then opens the door, if you come along and touch that doorknob a minute later then that could also be a way that the flu can spread.
Who is at highest risk for the flu?
Lee: Everybody is at risk for influenza, even otherwise healthy people; however, we know that there are certain populations that have the highest risk. These include both the young and the old. We have known for quite a while now that children less than five, especially those children less than two years of age, are at high risk. Adults over 65 years of age are also at high risk. Pregnant women, individuals living in nursing homes or other assisted care facilities, and Native Americans also appear to be at higher risk for influenza. And finally, individuals who have any underlying medical condition can also be at higher risk.
Some of the more common conditions that increase risk include respiratory conditions such as asthma, heart disease, neurologic disease, diabetes or severe obesity. Individuals with compromised immune systems or really any significant condition that affects one of the major organ systems of the body are at higher risk for severe complications from flu.
Why is the flu shot important?
Lee: The flu shot is vital to our efforts to combat influenza because it remains the single most effective way to prevent flu infection.
Now there are a lot of misconceptions about the flu vaccine. We recognize that the current versions of the flu vaccines are not perfect; however, they do work and they are effective at both preventing influenza and importantly, even if somebody catches influenza after vaccination, we know that it helps prevent some of the more severe complications. So, it both prevents the flu and, in individuals who have the flu, it may prevent or decrease the severity of the illness.
What do you say to healthy adults who do not get the flu shot?
Lee: The first thing that I would say is that if you did not get the flu shot and didn’t catch the flu, then that means you got lucky. I don’t think relying on good luck is necessarily the safest health strategy.
Anybody can get infected and anybody is at risk for severe complications. In fact, there are certain complications that seem to actually be more common in the young and the healthy. A classic example is secondary bacterial pneumonia due to a bacteria called Staphylococcus aureus, or Staph aureus. For whatever reason, these specific types of pneumonia tend to affect younger and healthier patients when they have the flu. They can be devastating and deadly illnesses.
Being relatively young and being relatively healthy does not get you off the hook in terms of your risk for catching the flu, or in terms of the possibility of severe complications.
What is herd immunity?
Lee: If enough people get vaccinated, the entire population (or herd) will be at least risk for transmission. This is referred to as herd immunity. Thus, the effect of getting vaccinated may have a role in protecting others around you as well. The minimum age for a flu shot is six months. Any infant less than six months of age is not able to get vaccinated and relies completely on those around him or her for protection. I would argue that getting a flu shot is not just something you do for yourself, but also for those around you and your loved ones.
What are some misconceptions about the flu shot?
Lee: One of the most common is that you can catch the flu itself from getting the flu vaccine. This is inaccurate and it’s simply not true. The reason I feel so confident in saying that is that all flu shots only contain either a completely inactivated or killed virus, or only specific influenza proteins. What that means is that the contents of the vaccine cannot cause an infection.
Sometimes what can happen is somebody can experience side effects that could be common to getting any type of shot, such as a sore arm, a low grade fever, a little bit of achiness, that sort of thing, and that gets mistaken for the flu.
Anybody who’s had a true rip-roaring case of flu would recognize the difference between how sick they felt with the flu versus a little bit of discomfort they may have had for several days after getting the shot.
What are some new flu vaccines in development?
Lee: There have been a number of important advances in recent years regarding flu vaccines. This was one of the lessons from the 2009 swine flu pandemic. We recognized that our capacity to rapidly develop necessary vaccines was significantly lacking.
Since that time a number of different manufacturing methods have been developed that increase both the capacity for the health system to make vaccines and the speed at which those vaccines can be manufactured.
The ultimate goal is to develop what’s called a “universal flu vaccine.” The flu vaccines that we use every year are different from most vaccines because we need to get a new shot every year. A universal flu vaccine would be a single shot that you get once to be protected from flu for the rest of your life, or at least for many years.
The reason this has been a challenge is that all previous versions of the vaccines that we use are based on the outer spike proteins of the virus itself and those outer spike proteins mutate very rapidly. So, over the course of a year, those proteins are constantly evolving and changing, which is why we need a new shot every year. The hope is that we can identify a way to make a vaccine that targets parts of the virus that don’t change from year to year and therefore, maybe one shot could give us longer lasting immunity.
Lee: The importance of flu vaccine. Everybody who is at least six months of age should get the flu shot this year and every year. It is the single most effective way to protect yourself and your loved ones from getting the flu.