The ongoing outbreak of coronavirus disease 2019 (COVID-19) has swept the world, prompting unprecedented measures like travel bans, lockdowns, and mask mandates.

The disease, caused by the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is highly contagious and has infected millions of people worldwide.

While COVID-19 is a new disease, it is not the first global outbreak of a viral illness. The world has faced epidemics and pandemics before, including severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS).

How does COVID-19 compare to previous outbreaks in terms of symptoms? Here are some of the key differences:.

Symptoms of COVID-19

COVID-19 is primarily a respiratory illness, and the most common symptoms include:.

Fever or chills
Cough
Shortness of breath or difficulty breathing
Fatigue
Muscle or body aches
Headache
New loss of taste or smell
Sore throat
Congestion or runny nose
Nausea or vomiting
Diarrhea

Not everyone who contracts COVID-19 experiences all of these symptoms, and some people may have no symptoms at all.

However, the disease can be severe or even fatal in some cases, particularly for older adults or those with underlying health conditions.

Symptoms of SARS

SARS is also caused by a coronavirus, although a different strain than the one responsible for COVID-19. The outbreak occurred in late 2002 and early 2003, primarily in mainland China and Hong Kong.

SARS causes an atypical pneumonia, with symptoms such as:.

Fever
Dry cough
Shortness of breath
Difficulty breathing
Chills or shaking
Muscle or body aches
Headache
Fatigue
Sore throat

SARS was highly contagious, but it was not as infectious as COVID-19. The disease eventually spread to more than two dozen countries, causing more than 8,000 cases and nearly 800 deaths.

Symptoms of MERS

MERS is another respiratory disease caused by a coronavirus. The outbreak began in 2012 in Saudi Arabia and has since spread to other countries in the Middle East and beyond. MERS symptoms include:.

Fever
Cough
Shortness of breath
Chills
Body aches
Sore throat

MERS is less contagious than either SARS or COVID-19, but it is also more deadly, with a mortality rate of around 35%. The virus is primarily spread through close contact with infected people or animals.

Comparing the Symptoms

While there is some overlap between the symptoms of COVID-19, SARS, and MERS, each disease has its own unique presentation. COVID-19 appears to be more contagious than either SARS or MERS, but it is less deadly than MERS.

Unlike SARS and MERS, COVID-19 can cause a loss of taste or smell, and it is also more likely to cause gastrointestinal symptoms like diarrhea or nausea.

Another key difference between COVID-19 and previous outbreaks is the speed and extent of its spread.

Thanks in part to modern travel and global interconnectedness, COVID-19 has spread far more rapidly and more widely than either SARS or MERS, and it has caused far more cases and deaths as a result.

Conclusion

While COVID-19, SARS, and MERS are all caused by coronaviruses and share some symptoms in common, they differ in terms of contagiousness, mortality rate, and other factors.

COVID-19 is a new disease, and scientists are still learning more about how it operates and how it compares to previous outbreaks. However, by understanding the similarities and differences between these diseases, we can better prepare ourselves and our communities to combat them.