Understanding the Different Types of Coronavirus

There is some debate about where coronaviruses got their name. One theory is that they are named after the sun. When scientists first isolated a coronavirus under a microscope, the spikes surrounding the virus reminded them of the corona of the sun. Corona also means "crown" in Latin, so other sources speculate that this virus family got its name because the spikes are reminiscent of a crown.

Whether they reminded scientists of the sun or a crown, the spikes are a defining feature of coronaviruses. These spikes are made of glycoproteins, chains of proteins with sugar attached that coronaviruses use to enter host cells. Coronaviruses are highly susceptible to mutation and are incredibly diverse. The primary affects animals, like bats and wild birds, but a few have crossed over into humans.

There are multiple types of coronaviruses, generally described as alpha, beta, gamma, and delta, and used to categorize different species of the virus. Alpha and beta infect only mammals, usually causing respiratory illnesses in humans and gastroenteritis in animals. Gamma and delta primarily affect birds, but some can also infect mammals.

Some coronavirus diseases in humans are generally mild, including those caused by types 229E, NL63, OC43, and HKU1. These coronavirus variants all symptoms like runny noses, sore throats, coughs, fevers, and headaches and are responsible for between 15 and 30 percents of all common colds in adults. These common viruses generally stay in the upper airway, which is why they do not tend to cause severe lower respiratory infections.

SARS-CoV, or severe acute respiratory syndrome coronavirus, causes a serious form of pneumonia known as SARS. In 2002, the virus spread from a small mammal to the people in Guangdong province, China, quickly spreading worldwide to more than 8,000 people in 29 countries. SARS was contained in 2003, and no new cases have been reported since 2004.

Symptoms of SARS usually occur within two to ten days of infection. The primary symptoms are a fever of 100.4°F or higher, cough, and difficulty breathing. People with SARS may also experience chills, shaking, chills, muscle aches, headache, and tiredness. In some people, lung symptoms worsen during the second week of the illness, even after the fever resolves, leading to pneumonia. During the outbreak, the overall death rate was as high as 12 percent; in those over 65, it was over 50 percent.

MERS, or Middle East respiratory syndrome coronavirus emerged in Saudi Arabia in 2012. This form of coronavirus was believed to be transferred to humans from infected dromedary camels. Some people with MERS do not exhibit any symptoms, but typically, the virus causes fever, cough, and shortness of breath. Some people may develop pneumonia.

MERS does not have a vaccine, and treatment focuses on symptom management. More severe illness may occur in older people and those with weakened immune systems or chronic conditions like cancer, diabetes, or chronic lung diseases; mechanical ventilation may be required. The World Health Organization estimates that about 35 percent of people with MERS have died, but this may not be accurate as many cases of MERS may be missed in the general population. This fatality rate is only among lab-confirmed cases.

SARS-CoV-2, or severe acute respiratory syndrome coronavirus 2, is the virus that causes COVID-19. It is believed to have emerged in Wuhan, China, at the end of 2019, and because it is highly transmissible, it spread quickly worldwide.

Common symptoms during the outbreak included fever, fatigue, and dry mouth, and some people experienced headaches, loss of appetite, sore throat, chest pain, chills, nausea, diarrhea, vomiting, or loss of taste or smell. Some people with COVID may not have any symptoms at all, but people 65 and older and infants younger than six months are at risk for severe disease. In addition to age, risk factors for severe COVID-19 include underlying health conditions like heart disease, diabetes, obesity, chronic lung disease, cancer, and chronic kidney disease.

Because of the speed at which COVID-19 spread, researchers worldwide raced to develop effective treatments. While there is no cure, people now have multiple treatment options. Several anti-viral medications are available that can inhibit viral replication and lessen the severity of the disease, but these medications must be started within five to seven days of the onset of symptoms to be effective.

COVID-19 vaccines have been approved since August 2021 and are an effective way to prevent severe COVID-19 infection. A monoclonal antibody is also available for moderately or severely immunocompromised people to prevent infection after exposure.

Influenza and coronavirus both cause respiratory illnesses, but they are different viruses. Flu does not spread as easily as COVID-19, and because COVID-19 may take longer to show symptoms and last longer than the flu, it may be contagious for a longer period.

Symptoms of the two can be very similar, so specific testing is needed to determine whether someone has flu or COVID-19. Common symptoms of these two illnesses include cough, fever, difficulty breathing, fatigue, sore throat, runny nose, headache, and body aches. GI symptoms, like vomiting and diarrhea, can also occur with either virus.

Overall, COVID-19 tends to cause more severe illness. Though both flu and COVID-19 can result in complications like pneumonia, sepsis, respiratory distress, or fluid in the lungs, secondary infections, like bacterial pneumonia or sinus infections, are more common with flu, while blood clots and multisystem inflammatory syndrome are more common with COVID-19.

People with COVID-19 are also at risk for long COVID. Long COVID is defined as a long-lasting or chronic condition that can be triggered by coronavirus. Symptoms can stay the same or come and go and can appear weeks or months after recovering from COVID-19. They include tiredness, brain fog, dizziness, sleep problems, headaches, and fast or irregular heartbeat.

Coronaviruses are zoonotic, which means that they can transfer from animals to humans. These viruses can go directly from an animal to a human, but sometimes there is an intermediate host. For example, in the case of MERS, people may have gotten the virus from camels, but the virus's natural host is believed to be bats. These bats then spread the virus to camels, which then spread it to humans.

While the virus that led to the worldwide COVID-19 pandemic has close relatives circulating in certain bat species in China, there are still questions about where the virus originated and how it spread to humans. Scientists have determined that SARS-CoV-2 is part of a family of viruses found in some bats in China and generally agree that the earliest infections and deaths are connected to a wildlife market in Wuhan. Wild animals susceptible to bat viruses were present in the market, including bamboo rats, raccoon dogs, and porcupines, but someone may have been infected with the virus in another area and then spread it through the market. Scientists have not found conclusive evidence proving where COVID-19 started or where it came from.

The CDC recommends specific strategies to prevent the spread of COVID-19 and other coronaviruses. Getting vaccinated can significantly lower the risk of getting severe COVID-19, hospitalization, and death. If you are sick, stay home and isolate from others if you have respiratory symptoms. If you have risk factors for severe illness, get tested and talk to your doctor about medication. Wearing a mask and practicing social distancing can also help lower the risk of spreading the virus.

If you have tested positive for coronavirus, you can manage mild symptoms at home if you are not at risk for severe illness. Contact your doctor about your symptoms and discuss what you should do and when you should seek emergency medical care. Fever, coughing, fatigue, sore throat, and congestion can generally be managed as you would manage the flu or a bad cold, but some symptoms do require emergency care. If you are having trouble breathing, experiencing confusion, feeling pain or pressure in your chest, having a hard time staying awake, or your lips or face are turning blue, call 911 or go to the emergency room right away.

Coronaviruses are a family of viruses that can cause respiratory illnesses in humans, but they vary significantly in severity. Coronoavirsus, like 229E, NL63, OC43, and HKU1, are responsible for the common cold, but others have been known to cause serious illness. The SARS outbreak in 2002 and 2003 ultimately affected 8,000 people in 29 countries, and while MERS is more regionally isolated, it has been estimated to be fatal in about 35 percent of cases.

When talking about coronaviruses, what comes to mind for many people is likely SARS-CoV-2, which caused the COVID-19 pandemic and killed more than 1.2 million people in the US. While vaccines, medications, and acquired immunity have changed the speed of the spread and the severity of the illness for some, it is still essential to stay informed about coronavirus as they have been shown to significantly impact public health. Practice good hygiene, follow public health guidelines, and consult a medical professional when necessary.