Human Coronavirus OC43, or HCoV-OC43, is one of the most prevalent viruses responsible for the common cold. It belongs to the extensive family of coronaviruses and was among the initial human coronaviruses identified by scientists in the mid-1960s. Most individuals will contract an OC43 infection at some point during their lives, experiencing it as a simple cold.
Symptoms and Illness Severity
An infection with HCoV-OC43 most commonly results in a mild to moderate upper-respiratory tract illness, with symptoms that are characteristic of the common cold. These include a runny nose, sore throat, cough, headache, and sometimes a low-grade fever or a general feeling of being unwell. The incubation period is short, with symptoms appearing within two to four days after exposure to the virus. For the majority of healthy adults and children, the illness is self-limiting, meaning it resolves on its own without specific medical intervention, within a short period.
While mild, OC43 can be more serious in specific populations. The virus is capable of causing more severe lower-respiratory tract infections, such as bronchitis and pneumonia. This is a more common outcome in infants, the elderly, and individuals with weakened immune systems or underlying cardiopulmonary conditions. In these vulnerable groups, what begins as a common cold can progress, requiring medical attention to manage the more significant respiratory symptoms.
Transmission and Seasonality
The primary method of transmission for HCoV-OC43 is through respiratory droplets generated when an infected person coughs or sneezes. These virus-containing droplets can be inhaled by others or can land on surfaces. Contact with these contaminated surfaces, followed by touching one’s own mouth, nose, or eyes, is another way the virus can spread.
OC43 infections exhibit a distinct seasonal pattern, particularly in temperate climates. The circulation of the virus tends to peak during the fall and winter months, similar to the seasonal patterns observed with influenza and other viruses that cause the common cold. This seasonality means that outbreaks are more common and widespread during colder periods when people tend to spend more time indoors, facilitating closer person-to-person contact and transmission.
Relationship to Other Coronaviruses
HCoV-OC43 is a member of the Betacoronavirus genus, placing it in the same viral family as more widely known pathogens like SARS-CoV-2 (the virus causing COVID-19) and MERS-CoV. Despite this genetic relationship, there are substantial differences in the diseases they cause. Infections with OC43 are mild, whereas SARS-CoV-2 and MERS-CoV are known to cause severe, often life-threatening respiratory illnesses with significantly higher mortality rates.
OC43 is one of four endemic human coronaviruses that have been circulating in the human population for a long time, the others being 229E, NL63, and HKU1. Scientific analysis suggests that HCoV-OC43 likely originated from a bovine (cow) coronavirus. Genetic studies estimate that this virus made the “jump” from cattle to humans sometime around the late 19th century, possibly around 1890.
Immunity and Treatment
Immunity developed after an HCoV-OC43 infection is not lifelong. The protective immune response wanes over time, which is why individuals can be reinfected with the same type of coronavirus and experience common colds multiple times throughout their lives. There is currently no specific vaccine available to prevent HCoV-OC43 infection.
As there is no targeted antiviral medication for HCoV-OC43, treatment is focused on managing symptoms and providing supportive care. This approach includes getting adequate rest, staying well-hydrated to help the body fight the infection, and using over-the-counter medications. Pain relievers and fever reducers can help manage symptoms like headache and fever. It is important to note that antibiotics are ineffective against viral infections like those caused by OC43.