COVID-19, caused by the SARS-CoV-2 virus, primarily spreads through respiratory droplets and aerosols. It can also transmit through direct contact with an infected person or indirectly through contaminated surfaces. A common question concerns the virus’s ability to survive in refrigerated environments and the potential risk this poses. This article explores SARS-CoV-2 survival in cold conditions and its implications for transmission from chilled items.
How Viruses Persist Outside the Body
Viruses, including SARS-CoV-2, are not independent living organisms; they require a host cell to replicate and remain infectious. Several factors influence how long viruses stay viable on surfaces and in different environments. Temperature is a significant factor, with lower temperatures generally preserving viruses by slowing their degradation. Humidity also plays a role, as viruses may persist longer at certain humidity levels. The type of surface (porous or non-porous) affects viral stability, and organic matter like mucus or saliva can also shield viruses, helping them maintain infectivity.
SARS-CoV-2 and Cold Temperatures
Scientific studies have investigated the stability of SARS-CoV-2 in refrigerated and frozen conditions, consistently showing that cold temperatures can extend the virus’s viability. Unlike heat, which inactivates viruses, cold slows down their natural decay processes. For instance, SARS-CoV-2 has been found to survive for more than 14 days at 4°C. On non-porous surfaces like stainless steel and plastic, the virus can remain infectious for several days at room temperature, and even longer at colder temperatures. Some research indicates that SARS-CoV-2 can persist on cold and moist surfaces, such as those found in cold chain environments, for over three weeks, with pseudovirus studies showing survival for over 20 days on polyethylene plastic, stainless steel, and Teflon surfaces.
Understanding Transmission Risk from Chilled Items
While SARS-CoV-2 can survive in refrigerated conditions for extended periods, the risk of transmission to humans from food or food packaging stored in a fridge is considered very low. The primary modes of SARS-CoV-2 transmission are through respiratory droplets and aerosols, which are released when an infected person coughs, sneezes, or talks. Transmission through indirect contact with contaminated surfaces, known as fomite transmission, is possible but generally less efficient than airborne transmission. For infection to occur via contaminated surfaces, the virus needs to be picked up from the surface and then transferred to the eyes, nose, or mouth in sufficient quantity to initiate an infection. The number of virus particles picked up by touching a surface is typically very small, and the amount needed to cause infection is significantly higher, leading to a scientific consensus from organizations like the USDA, FDA, and CDC that the risk of transmission through food or food packaging is very low.
Food Safety Guidelines
Given the understanding of SARS-CoV-2 transmission, reinforcing general food safety and hygiene practices remains the most effective approach. Regularly washing hands thoroughly with soap and water before, during, and after preparing food, especially after handling raw ingredients, is a fundamental practice for preventing the spread of many pathogens, including SARS-CoV-2. Maintaining clean kitchen surfaces is also important. Worktops, cutting boards, and utensils should be washed with hot, soapy water after each use, particularly after contact with raw meat, poultry, or eggs. Using separate cutting boards for raw meats and produce can prevent cross-contamination, and these universal food safety principles effectively reduce the risk of various foodborne illnesses, contributing to a safer food environment.