Human coronaviruses (HCoVs) commonly circulate among people and generally cause mild respiratory illnesses, often contributing to the common cold. Coronavirus OC43 is one of the oldest known HCoVs, circulating for over a century. It is a routine cause of winter respiratory infections, and understanding its duration involves considering both the length of the illness within the body and the virus’s survival time outside a host.
Context: What is Coronavirus OC43?
Human Coronavirus OC43 (HCoV-OC43) is classified as a Betacoronavirus, placing it in the same genus as pathogens like SARS-CoV-2. OC43 is considered one of the four main endemic coronaviruses, meaning it is constantly present within the population. It is a major contributor to seasonal upper respiratory tract infections worldwide, accounting for 10% to 30% of all common colds.
Infection with OC43 typically results in a mild presentation, often mistaken for other cold viruses. Symptoms include a runny nose, cough, sore throat, and a low-grade fever. Most infections remain self-limiting and confined to the upper airways. While the illness is usually mild, certain groups may experience more severe outcomes, including infants, the elderly, and individuals with compromised immune systems. In these vulnerable populations, OC43 can sometimes lead to lower respiratory tract complications such as bronchitis or pneumonia.
Duration of the Acute Infection
The length of an active OC43 infection within the body is short and predictable, similar to other common cold viruses. Following exposure, the incubation period is relatively quick, with symptoms usually appearing approximately two to four days after the initial infection. Once symptoms begin, the resulting cold is considered a self-limiting illness.
The duration of noticeable symptoms typically lasts only a few days for most healthy individuals. This timeline covers the period where symptoms like nasal congestion and malaise are most prominent before they begin to subside. Symptom resolution is a strong indicator that the virus has been largely cleared, signifying the end of the acute infection phase.
The infectious period, or the time an individual can transmit the virus to others, is concentrated around the peak of the illness. Transmission occurs quickly through respiratory droplets, starting shortly before symptoms are at their worst. The risk of spread tends to decline rapidly as the symptoms improve and the viral load in the upper respiratory tract decreases.
Factors Influencing Recovery
Factors such as age and underlying health conditions can significantly influence how long an infection lasts. Individuals with chronic respiratory diseases, such as asthma, or those with weakened immune systems may experience a longer duration of illness. Very young children and older adults are more susceptible to the virus affecting the lower respiratory tract, which can extend the recovery timeline beyond the typical few days.
Environmental Stability and Surface Survival
The duration of an OC43 infection also relates to the virus’s ability to remain infectious outside of the human body on various surfaces. Research indicates that OC43 can exhibit a notable degree of stability on non-porous materials and even on human skin. On the surface of human skin, the virus has been shown to have a median survival time of approximately 25 hours.
This stability on skin is actually higher than that of SARS-CoV-2, which has been measured at a shorter duration on the same medium. This persistence increases the risk of contact transmission, especially if proper hand hygiene is not maintained. However, common alcohol-based disinfectants are effective at rapidly inactivating the virus on the skin.
The virus’s survival on common non-porous surfaces like stainless steel is heavily influenced by environmental factors and the presence of bodily fluids. Under conditions of low humidity and cooler temperatures, OC43 can remain infectious for an extended period, in some studies lasting up to 22 days. The presence of high mucin content, which mimics natural bodily fluids like saliva, can also enhance the virus’s stability on surfaces. This suggests that while heat and humidity generally degrade the virus quickly, colder and drier environments allow OC43 to persist and pose a transmission risk for a much longer time.