The influenza virus, commonly known as the flu, is a respiratory illness. While primarily spreading through airborne droplets from coughs or sneezes, it can also transmit indirectly by contaminating surfaces. Understanding how long these viruses remain viable on everyday objects helps minimize their spread in communities.
How Long Flu Viruses Persist on Surfaces
Influenza viruses persist on surfaces for varying durations, depending on the material. On hard, non-porous surfaces such as stainless steel, plastic, and doorknobs, the flu virus can remain infectious for 24 to 48 hours, sometimes up to seven days, though infectivity declines rapidly.
On soft, porous materials like cloth, paper, and tissues, the virus’s survival time is considerably shorter. It generally remains viable for less than 8 to 12 hours. When transferred to hands, the virus’s lifespan is very brief, often lasting only up to five minutes. The initial amount of virus deposited, known as the viral load, also influences how long it can remain infectious on a surface.
What Affects Virus Survival
Several environmental and viral characteristics influence how long the flu virus remains viable and infectious on surfaces. The type of surface plays a significant role, with viruses generally surviving longer on non-porous materials like metal and plastic compared to porous materials such as fabrics and paper. Porous surfaces tend to absorb moisture more quickly, which can lead to faster viral degradation. Notably, copper surfaces can inactivate flu viruses more rapidly than stainless steel.
Temperature is another important factor, as colder conditions typically extend the virus’s survival time on surfaces. Conversely, higher temperatures tend to shorten its lifespan. Humidity also influences viral persistence; some research indicates that influenza virus survival can be minimal at intermediate humidity levels, specifically between 40% and 70%. Additionally, the presence of organic matter, such as mucus or saliva, can offer a protective layer to the virus, allowing it to remain viable for longer periods.
Stopping Flu Spread from Surfaces
Minimizing the risk of flu transmission from contaminated surfaces involves a combination of practical measures. Frequent and thorough hand hygiene is a primary defense, including washing hands with soap and water for at least 20 seconds. If soap and water are unavailable, an alcohol-based hand sanitizer with at least 60% alcohol can be used. Avoiding touching the eyes, nose, or mouth after touching public surfaces is also important to prevent self-inoculation.
Regular cleaning and disinfection of frequently touched surfaces are also recommended. This includes items like doorknobs, light switches, countertops, keyboards, and shared electronic devices. Clean surfaces with soap and water first to remove dirt and organic matter, then follow with an appropriate disinfectant.
Practicing good respiratory etiquette helps prevent the initial deposition of viruses onto surfaces. Cover coughs and sneezes with a tissue, or into the elbow if a tissue is not immediately available. Used tissues should be disposed of promptly. Staying home when sick also plays a significant role in reducing viral load and minimizing surface contamination. Remain home until at least 24 hours after your fever has subsided without fever-reducing medication.