Influenza can be transmitted through the air by larger respiratory droplets and smaller aerosolized particles. It may also be spread through contact with contaminated surfaces. There are many ways to prevent getting sick with the flu.
Influenza viruses cause a respiratory illness that you may know more commonly as “the flu.” In the United States, the Centers for Disease Control and Prevention (CDC) estimates that there were
The flu is contagious, meaning that it can spread from person to person. But how is it spread? Is it airborne, or is it spread by other means, such as by droplets or contact? Keep reading below as we explore what to know about how influenza spreads.
So how exactly is influenza spread? Is it airborne, spread by droplets, or through contact? Why not all three?
Let’s explore what we know about each type of transmission.
Respiratory droplets
According to the
Respiratory droplets are made when you sneeze, cough, or talk. If respiratory droplets containing influenza virus come into contact with your mucus membranes, such as those in your nose or mouth, you can get sick.
Research suggests that respiratory droplets are on the larger side, typically
That means you have to be pretty close to someone to contract the virus from them. However, respiratory droplets can fall onto various objects and surfaces, which leads us to our next method.
Contact
When respiratory droplets fall out of the air, they can land on nearby surfaces. Depending on the conditions, influenza virus can still be infectious for many hours.
For example, the virus can survive on hard, non-porous surfaces for
You can contract the virus if you touch a contaminated surface and then touch your nose or mouth.
Airborne transmission
When we talk about airborne transmission, we’re generally referring to aerosolized particles containing influenza virus that are
Unlike respiratory droplets (made when coughing or sneezing), which tend to land in the nose and throat, airborne particles can travel
The
Indeed, a
Further, researchers conducting a small 2018 study involving people with confirmed influenza and symptomatic were able to recover infectious virus from fine aerosols collected from breathing samples.
Overall, the exact contribution of the airborne route of influenza transmission
Yes.
The Environmental Protection Agency (EPA) notes that to be effective at removing viruses from the air, an air cleaner must be able to remove very small airborne particles, which it defines as those between 0.1 to 1 µm in size.
They recommend checking the product information provided by the manufacturer to verify that an air cleaner can remove particles of this size.
While air filtration can lower levels of virus in the air, it isn’t a substitute for other preventive measures, such as avoiding contact with people who are sick, handwashing frequently, and cleaning high-touch surfaces.
The amount of time that influenza stays in the air can depend on the size of the particles that it’s in.
For example, respiratory droplets between the sizes of 5 and 100 µm can remain in the air for
Aerosolized, or airborne, particles can stay in the air for longer. This is particularly true if there’s poor airflow or ventilation.
One 2015 study involved aerosolizing a laboratory strain of influenza and sampling the air. It found that after 60 to 90 minutes, levels of infectious virus in the air were still enough to cause an infection.
Aside from particle size, there are several other factors that can affect how long the influenza virus is infectious in the air or on surfaces. These
- Temperature: The influenza virus is more stable at lower temperatures.
- Humidity: Influenza virus is generally more likely to spread at lower humidity levels.
- UV radiation: Exposure to UV radiation, such as from sunlight, can inactivate influenza viruses.
Does winter weather cause influenza?
Yes and no. While the season doesn’t directly cause an influenza infection, some winter climates
In many places the winter climate is colder and dryer, which can help the virus survive longer in the air and on surfaces. In addition, you’re more likely to spend time in crowded indoor spaces with poor ventilation and less likely to be using sunscreen (although it’s still important to).
This can create an ideal situation for influenza to spread across communities during the winter months.
According to the
The protection goes both ways and can protect you and your community. If you currently have the flu, wearing a mask can help lower your risk of passing it to others. If you don’t have the flu, a mask can prevent you from breathing in particles containing the virus.
A
The authors of the analysis do point out that
If you choose to
Yes. Hand hygiene, including using hand sanitizer, can significantly protect against influenza. Hand sanitizer can be particularly beneficial when soap and water are not readily available.
For example, one
However, it’s important to note that some research suggests hand sanitizer is less effective than handwashing when the influenza virus is found in mucus.
These results align with the CDC guidance that handwashing with soap and water is the
Hand sanitizer can be used if soap and water are not available. Just be sure to use one that contains
Influenza virus can spread in many different ways.
It can be transmitted through the air via respiratory droplets and airborne transmission. You can also contract the flu virus from contacting contaminated surfaces and then touching your nose or mouth.
There are many ways to prevent the flu. Some of these prevention methods we’ve discussed in detail here include practicing good hand hygiene, using an air filtration system, or wearing a mask.
Another great way to prevent contracting the flu virus is getting the seasonal flu vaccine. Receiving the flu vaccine each year can help prevent sickness and complications from the flu. If you do get sick, it can help reduce the length and severity of your illness.