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How do all these terms fit together? "Coronavirus" is a generic term that includes a large family of viruses, similar to saying someone has the flu. SARS-CoV-2 is a specific virus that can cause COVID-19, a disease. As WHO explains, this is similar to differentiating HIV and AIDS — HIV is a virus that causes AIDS. Outlined on their website ...
- Overview
- What is a coronavirus?
- What is SARS?
- How does COVID-19 differ from SARS?
- Severity
- Transmission
- Molecular factors
- Receptor binding
- Will COVID-19 be around longer than SARS?
- The bottom line
This article was updated on April 29, 2020, to include additional symptoms of the 2019 coronavirus.
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COVID-19, which is caused by the 2019 coronavirus, has been dominating the news. However, you may have first become familiar with the term coronavirus during the severe acute respiratory syndrome (SARS) outbreak in 2003.
Both COVID-19 and SARS are caused by coronaviruses. The virus that causes SARS is known as SARS-CoV, while the virus that causes COVID-19 is known as SARS-CoV-2. There are also other types of human coronaviruses.
Coronaviruses are a very diverse family of viruses. They have a large host range, which includes humans. However, the greatest amount of coronavirus diversity is seen in bats.
Coronaviruses have spiky projections on their surface that look like crowns. Corona means “crown” in Latin — and that’s how this family of viruses got their name.
Most of the time, human coronaviruses cause mild respiratory illnesses like the common cold. In fact, four types of human coronaviruses cause 10 to 30 percent of upper respiratory tract infections in adults.
A new type of coronavirus can emerge when an animal coronavirus develops the ability to transfer a virus to humans. When germs are transmitted from an animal to a human, it’s called zoonotic transmission.
Coronaviruses that make the jump to human hosts can cause serious illness. This can be due to a variety of factors, particularly humans’ lack of immunity to the new virus. Here are some examples of such coronaviruses:
•SARS-CoV, the virus that caused SARS, which was first identified in 2003
SARS is the name of the respiratory illness that’s caused by SARS-CoV. The acronym SARS stands for severe acute respiratory syndrome.
The global SARS outbreak lasted from late 2002 to mid-2003. During this time, over 8,000 people contracted the virus and 774 people died.
The origin of SARS-CoV is thought to be bats. It’s believed that the virus passed from bats to an intermediate animal host, the civet cat, before jumping to humans.
Fever is one of the first symptoms of SARS. This may be accompanied by other symptoms, such as:
•cough
•malaise or fatigue
COVID-19 and SARS are similar in many ways. For example, both:
•are respiratory illnesses caused by coronaviruses
•are transmitted by respiratory droplets produced when a person with the virus coughs or sneezes or by contact with objects or surfaces containing the virus
•have similar stability in the air and on various surfaces
•can lead to potentially serious illness, sometimes requiring oxygen or mechanical ventilation
•can have worsening symptoms later on in the illness
It’s estimated that 20 percent of people with COVID-19 will need to be hospitalized for treatment. A smaller percentage of this group will need mechanical ventilation.
SARS cases were more severe, in general. It’s estimated that 20 to 30 percent of people with SARS required mechanical ventilation.
Estimates of the mortality rate of COVID-19 vary greatly depending on factors like location and the characteristics of a population. Generally speaking, mortality rates for COVID-19 have been estimated to range between 0.25 and 3 percent, though rates vary from country to country.
SARS has a higher mortality rate than COVID-19. The estimated mortality rate is about 10 percent, with some patient populations having a mortality rate as high as 45 percent.
SARS-CoV-2 appears to be transmitted more easily than SARS-CoV. One possible explanation is that the amount of virus, or viral load, appears to be highest in the nose and throat of people with COVID-19 shortly after symptoms develop.
This is in contrast to SARS, in which viral loads peaked much later in the illness. This indicates that people with COVID-19 may be transmitting the virus earlier in the course of the infection, just as their symptoms are developing but before they begin to worsen.
According to the Centers for Disease Control and Prevention (CDC), research suggests that SARS-CoV-2 can be transmitted by people who are not showing symptoms of illness, which is rarely seen with a SARS-CoV infection.
Another difference between the two viral infections is the fact that there haven’t been any reported cases of SARS-CoV transmission before symptom development.
A recent study of the complete genetic information (genome) of SARS-CoV-2 samples found that the virus was more closely related to bat coronaviruses than the SARS virus. The new coronavirus has a 79 percent genetic similarity to the SARS virus.
The receptor binding site of SARS-CoV-2 was also compared to other coronaviruses. Remember that to enter a cell, a virus needs to interact with proteins on the cell’s surface (receptors). The virus does this via proteins on its own surface.
Studies are underway to see how SARS-COV-2 binds to and enters cells in comparison to SARS. Results have so far been varied.
It’s also important to note that the research below was performed only with proteins and not in the context of an entire virus.
A recent study has confirmed that both SARS-CoV-2 and SARS-CoV use the same host cell receptor. It also found that, for both viruses, the viral proteins used for host cell entry bind to the receptor with the same tightness (affinity).
Another recent study compared the specific area of the viral protein that’s responsible for binding to the host cell receptor. Researchers observed that the receptor binding site of SARS-CoV-2 binds to the host cell receptor with a higher affinity than that of SARS-CoV.
There have been no global SARS outbreaks since 2003. The last reported cases were in 2004 and were acquired in a lab. There have been no more cases reported since then.
SARS has been successfully contained using public health measures, such as:
•early case detection and isolation
•contact tracing and isolation
•social distancing
Will implementing the same measures help COVID-19 go away? In this case, it may be more difficult.
COVID-19 and SARS are both caused by coronaviruses. The viruses that cause these illnesses likely originated in animals before they were transmitted to humans by an intermediate host.
There are many similarities between COVID-19 and SARS. However, there are also important differences. COVID-19 cases can range from mild to severe, while SARS cases, in general, were more severe. But SARS-CoV-2, the virus that causes COVID-19, is transmitted more easily.
There are also some differences in the symptoms of the two illnesses.
There has not been a documented case of SARS since 2004, as strict public health measures were implemented to contain the transmission of SARS-CoV, the virus that causes it.
Jul 27, 2020 · Sound familiar? While there are similarities, these two respiratory illnesses are quite distinct. Learn the differences between COVID-19 and SARS and the best practices to prevent infection. What causes SARS and COVID-19? Both SARS and COVID-19 are respiratory illnesses that are caused by a specific human coronavirus.
Apr 30, 2020 · Dear Editor. SARS‐CoV (causative pathogen of Severe Acute Respiratory Syndrome or SARS) and SARS‐CoV‐2 (causative pathogen of Coronavirus Disease 2019 or COVID‐19) are positive‐sense RNA viruses belonging to the family of Coronaviridae, able to cause severe respiratory diseases. 1, 2, 3, 4.
- Antonio Caldaria, Claudio Conforti, Nicola Di Meo, Caterina Dianzani, Mohammad Jafferany, Torello Lo...
- 2020
Mar 15, 2021 · A 2020 study comparing SARS-CoV and SARS-CoV-2 stated that the viral load is higher and lasts longer in the lower respiratory tract in people that experience severe COVID-19 illness.
Feb 2, 2021 · Science News. from research organizations. Explaining differences between the viruses that cause COVID-19 and SARS. Researchers make discoveries to better understand SARS-CoV-2 virus....
Sep 1, 2023 · Throughout the COVID-19 pandemic, many variants of SARS-CoV-2 have been found in the United States and globally. Scientists use multiple classification systems to describe and communicate similarities and differences between SARS-CoV-2 viruses.
