The influenza virus, commonly called the flu, is a contagious respiratory illness that can lead to severe complications, especially in vulnerable populations. Transmission occurs when an infected person expels virus-laden respiratory particles into the air. When symptomatic, using non-pharmaceutical interventions (NPIs) like face masks is an effective measure to protect others and limit the spread of infection to family members, colleagues, or the community.
Masking for Source Control
Influenza viruses spread primarily through respiratory droplets and aerosols generated when an infected person talks, coughs, or sneezes. These particles vary in size, from large droplets that fall quickly to smaller aerosols that can linger in the air. A symptomatic person wearing a mask intercepts these particles directly at the source.
When an infected individual wears a mask, it acts as “source control,” trapping the virus-carrying particles before they can enter the environment and potentially infect others. Studies have demonstrated that wearing a surgical mask can significantly reduce the number of virus particles expelled during exhalation.
By capturing the droplets and aerosols closest to the mouth and nose, the mask decreases the viral dose available for others to breathe in. This mechanism focuses on protecting the community, rather than protecting the wearer from inhaling external pathogens. Although the flu virus can survive on unwashed hands, the primary route of transmission is through these respiratory particles, making source control a highly effective intervention.
Practical Guidance on Mask Types and Timing
For a person with the flu, the most practical and effective choice for source control is a standard disposable surgical mask. These masks are designed to block large-particle droplets and are generally more comfortable to wear for extended periods than tighter-fitting respirators. While N95 respirators offer superior filtration and a tighter seal, their primary function is to protect the wearer, making them unnecessary for the sole purpose of protecting others from the flu.
The timing of mask use should align with any situation where you cannot maintain physical separation from others. The mask should be worn anytime you must leave isolation, such as for a necessary medical appointment or a trip to the pharmacy. If you are sharing a home with others, especially those at high risk for severe illness, you should wear the mask when you are in shared spaces like the kitchen or living room.
Proper Application
Before touching the mask, wash your hands with soap and water or use an alcohol-based hand sanitizer. When donning the mask, ensure the stiff, moldable edge is positioned over the bridge of your nose and that the mask covers your mouth and chin completely. Pinch the metallic strip to conform it to the shape of your nose to minimize gaps.
Safe Removal
When removing the mask, consider the front surface to be contaminated and avoid touching it. Remove the mask by holding only the ear loops or ties, carefully pulling it away from your face. The mask should be immediately discarded into a closed waste bin, and you must perform hand hygiene again immediately afterward. Replace the mask if it becomes soiled, wet, or damp, as moisture reduces its effectiveness.
Integrating Masking with Other Mitigation Strategies
Masking is most effective when combined with other protective actions to create a layered defense against flu transmission. The single most important action is isolation, meaning you should stay home when you are sick with flu symptoms to eliminate the risk of spreading the virus.
Strict hand hygiene is a necessary complement to masking, as the influenza virus can survive on surfaces and be transferred by contact. You should wash your hands frequently for at least 20 seconds, especially after coughing, sneezing, or touching your mask.
You should also practice good respiratory etiquette, even while wearing a mask. If you need to cough or sneeze, do so into your elbow or a tissue to contain the particles. Regularly cleaning and disinfecting high-touch surfaces in your home, such as doorknobs, remote controls, and counters, also helps to reduce the risk of indirect transmission.
These non-pharmaceutical interventions work together to reduce the viral load in the environment and break the chains of transmission.