How long does the cold/flu virus live on surfaces?

How long a virus survives on a surface depends on what type of virus it is, how warm or moist its surroundings are, and the type of surface it has contaminated. In general, influenza A viruses remain infectious for up to 4 hours, but rarely more than 9 hours, while cold viruses can remain infectious for up to 24 hours. Viruses tend to survive longer on hard, nonporous surfaces than porous surfaces. There is a lack of research regarding how long influenza B viruses remain infectious. Viruses degrade quickly and although they can be detected on surfaces up to days later, they are generally not infectious for this length of time.

How long do flu viruses remain infectious?

A 2011 study showed that influenza A viruses are likely to survive and remain infectious on most surfaces for at least 4 hours, though rarely more than 9 hours. Metallic and non-metallic hard (non-porous) surfaces pose the greatest risk and surfaces that allowed influenza A viruses to survive for between four and nine hours included light switches made of polyvinyl chloride and a computer keyboard. These should be regularly cleaned if they are in an area where people frequently touch them.

Surfaces that viruses were unlikely to remain viable after four hours on included wood, particularly varnished wood or pine (contains pine oil), silver or antimicrobial agent impregnated cloths, and porous items, like soft toys and clothes.

An earlier study, conducted in 1982 looked at how long laboratory-grown viruses survived on various surfaces. Both influenza A and B viruses survived for 24–48 hr on hard, nonporous surfaces such as stainless steel and plastic but survived for <8–12 hr on cloth, paper, and tissues. The study concluded that the transmission of the virus from donors who are shedding large amounts could occur for 2–8 hr via stainless steel surfaces and for up to 15 minutes via paper tissues. Viruses survived on hands for up to 5 min after transfer from the environmental surfaces.

Another study from 2008 reported that Influenza A viruses tested by cell culture were detectable for up to 3 days when they were inoculated at high concentrations; this increased to up to 17 days in the presence of respiratory mucus. An influenza B virus (B/Hong Kong/335/2001) was still infectious after 1 day when it was mixed with respiratory mucus.

It is important to distinguish between viruses that can be detected but are not infectious and those that are infectious. Viruses must infect the cells of a living creature to multiply because they cannot multiply on their own. They are not actually living creatures, and once outside a living cell, they start to degrade and disintegrate. These weakened viruses are unable to attach to cells and spread their genetic material, although laboratory investigations such as polymerase chain reaction (PCR) may detect viral DNA remnants, yielding a positive result. But an intact virus is necessary for infection.

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How long do cold viruses remain infectious?

Common colds are caused by a plethora of viruses, and there are few studies that investigate surface infectious rates. In general, although some can be detected on indoor surfaces for up to seven days, they are infectious only for up to 24 hours. Generally, they last longer on hard, nonporous surfaces such as plastic and stainless steel than porous materials like facial tissues.

Most cold and flu viruses are enveloped viruses A enveloped virus, and they disintegrate easily, unlike non-enveloped ones such as norovirus which can be viable on surfaces for weeks.

Temperature, ultraviolet radiation from sunlight, pH changes and salt can play a role in weakening a viral envelope. Viruses also tend to be more stable in warm, moist environments for example, inside a person’s nostrils, throat, or bronchial tree, than non-moist or dry environments.

This is why cold and flu viruses remain infectious on non-porous hard surfaces rather than porous surfaces like fabric and tissues, because porous surfaces suck moisture away from the viruses, causing the structures to collapse.

But not all non-porous surfaces serve as ideal havens for viruses. Copper surfaces, which are naturally antiviral and antibacterial, stop the virus from being infectious within six hours.

What is the best way to prevent cold/flu virus transmission from surfaces?

Studies have shown that flu viruses can remain infectious for 4 to 9 hours and cold viruses for up to 24 hours, so frequent cleaning of commonly touched items and surfaces throughout the working day, particularly if people with symptoms are present (for example in doctor’s waiting rooms), can help reduce transmission.

Classrooms, offices, and living rooms, which are left unoccupied overnight, are unlikely to contain much viable virus on surfaces by the next morning.

Washing your hands often is a critical step in preventing colds, especially when you’re in close contact with a sick person. Use disinfectants to clean objects or areas that have been in contact with individuals who are sick. Chlorine, hydrogen peroxide, soaps, detergents, or alcohol-based gels all disrupt the capsules of the viruses, and they’re no longer capable of being infectious.

If you’re around someone with a cold, avoid touching your face and wash your hands frequently, and tell them to take a sick day. If you’re sick, stay home and cover coughs and sneezes.

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