The emergence of COVID-19 brought with it many questions about how the virus spreads. Early in the pandemic, there was considerable focus on how long the SARS-CoV-2 virus might linger on surfaces. Understanding the virus’s persistence on these surfaces was a significant concern for public health and daily life, prompting discussions about cleaning practices and potential exposure routes. This initial focus helped shape early guidance on preventing transmission in various environments.
How Long COVID-19 Survives on Surfaces
Studies indicate that the SARS-CoV-2 virus can remain infectious for different durations depending on the surface type and environmental conditions. On non-porous surfaces like plastic and stainless steel, the virus can persist for up to 72 hours, with some studies showing viability up to 28 days under specific laboratory conditions, such as lower temperatures. In contrast, porous surfaces tend to support virus survival for shorter periods; for example, on cardboard, the virus typically remains viable for up to 24 hours.
The survival time is also influenced by environmental factors such as temperature and humidity. Lower temperatures allow the virus to remain infectious for longer periods, while higher temperatures can reduce its viability. The presence of organic matter on a surface can also offer some protection to the virus, extending its survival. Studies have noted that the virus’s half-life is approximately 5.6 hours on stainless steel and 6.8 hours on plastic.
Risk of Transmission from Surfaces
While the SARS-CoV-2 virus can survive on surfaces for varying lengths of time, the risk of contracting COVID-19 through contaminated surfaces is considered low. The primary route of transmission for COVID-19 is through respiratory droplets and aerosols expelled by an infected person when they breathe, cough, sneeze, talk, or sing. These airborne particles are far more likely to cause infection than touching a surface.
For surface transmission, an infected individual would need to contaminate a surface, and another person would then need to touch it and immediately touch their eyes, nose, or mouth before the virus inactivates. The amount of viable virus on surfaces decreases significantly over time, making it unlikely for someone to pick up an infective dose from casual contact with a surface after a few hours. Transmission through surfaces is considered a less common pathway.
Effective Cleaning and Disinfection
Maintaining good hygiene practices remains a sensible approach to reducing germ spread in homes and workplaces. Cleaning surfaces with soap and water effectively removes most germs, dirt, and impurities, significantly reducing the risk of infection from surfaces. For most routine situations, cleaning alone is sufficient to manage the presence of virus particles.
Disinfection is important when someone in the household is sick with COVID-19 or has tested positive within 24 hours. Focus on frequently touched surfaces such as doorknobs, light switches, tables, and countertops. Common household disinfectants registered by the Environmental Protection Agency (EPA) are effective against SARS-CoV-2, and diluted household bleach solutions can also be used on appropriate surfaces. Always follow the manufacturer’s instructions for any cleaning or disinfecting product, paying close attention to the recommended contact time, and ensure proper ventilation during and after application. Wearing disposable gloves during cleaning and washing hands thoroughly afterward are also advisable steps.