This article was updated on April 29, 2020, to include additional symptoms of the 2019 coronavirus.
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.
Despite similar names, there are several differences between the coronaviruses that cause COVID-19 and SARS. Keep reading as we explore coronaviruses and how they compare to each other.
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
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
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 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,
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:
Respiratory symptoms can worsen, leading to shortness of breath. Serious cases rapidly progress, leading to pneumonia or respiratory distress.
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 - have similar at-risk groups, such as older adults and those with underlying health conditions
However, the two illnesses and the viruses that cause them are also different in several important ways. Let’s take a closer look.
Overall, the symptoms of COVID-19 and SARS are similar. But there are some subtle differences.
| Symptoms | COVID-19 | SARS |
| Common symptoms | fever cough fatigue shortness of breath muscle aches and pains headaches diarrhea | fever cough malaise body aches and pains headache shortness of breath |
| Less common symptoms | runny or stuffy nose sore throat nausea chills (with or without repeated shaking) loss of taste loss of smell | diarrhea chills |
COVID-19 Symptoms Usually Show Up in This Order
It’s estimated that
SARS cases were more severe, in general. It’s estimated that
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
SARS-CoV-2 appears to be transmitted
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
Another difference between the two viral infections is the fact that there
A
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.
When the protein sequence of the SARS-CoV-2 receptor binding site was analyzed, an interesting result was found. While SARS-CoV-2 is overall more similar to bat coronaviruses, the receptor binding site was more similar to SARS-CoV.
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
Another
If indeed SARS-CoV-2 has a higher binding affinity for its host cell receptor, this could also explain why it appears to be transmitted more easily than SARS-CoV.
There have been no global SARS outbreaks
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.
Some factors that may contribute to COVID-19 being around for longer include the following:
About 80 percent of people with COVID-19 have a mild illness. Some may not even know that they’re sick. This makes it harder to determine who has developed a viral infection and who has not.- People with COVID-19 appear to shed the virus earlier in the course of their infection than people with SARS. This makes it more difficult to detect who has the virus and isolate them before they transfer it to others.
- SARS-CoV-2 is now being easily transmitted within communities. This was not the case with SARS-CoV, which was more commonly transferred in healthcare settings.
- We’re even more globally connected than we were in 2003, making it easier for SARS-CoV-2 to be transmitted between regions and countries.
Some viruses, such as those that cause the flu and the common cold, follow seasonal patterns. There has been no evidence of seasonal variation with SARS-CoV-2, which causes COVID-19.
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.
COVID-19 may be more challenging to contain because the virus that causes this disease (SARS-CoV-2) is transferred more easily and the illness often causes mild symptoms.