Health and Science

COVID Compared

COVID-19 has consumed our lives since its outbreak. Millions of people were infected, businesses closed, and masks became part of the new norm. 

But some may be familiar with an earlier pandemic: SARS (severe acute respiratory syndrome). Coined the “first pandemic of the twenty-first century”, SARS was first reported in Guangdong, China in November of 2002 and subsequently swept through continents and a total of twenty-nine countries. Both pandemics are caused by coronaviruses, which is a large family of viruses that have a casing of lipids, or fats. This casing protects the virus and allows pathogens to survive on surfaces for a certain amount of time. But the important distinction is that the coronaviruses are slightly different–COVID-19 is caused by SARS-CoV-2 and SARS is caused by SARS-CoV. 

Evident by the names, both diseases are closely related to each other. The RNA genomes are 86% identical. For a virus, 86% indicates the two are extremely similar. Viruses mutate rapidly-a virus makes thousands of copies of its genetic information in a matter of hours. 

Symptoms for both viral diseases include a high fever, dry cough, and shortness of breath. However, COVID can also lead to a loss of taste and smell, fatigue, congestion, chest pain, and confusion. When both viruses were first reported, there were no diagnostics, vaccines, or therapeutics available. By April of 2003 (middle of the SARS pandemic), three diagnostic tests were in development. But of those three, one was unreliable and the other two could only be used late in the course of the disease. For COVID, this development occurred at a much quicker rate: by September 2020, the FDA had already authorized two hundred thirty-five tests, including a variety of molecular, antibody, and antigen tests. 

So why has the world shut down for COVID but not for SARS even though SARS has a much higher fatality rate?  SARS was not as devastating largely because it is not as easily transmitted. SARS spreads from much closer contact, for example, between family members. It can’t be spread through pre-symptomatic transmission, which means a person does not spread the virus, even if they are infected, unless they show symptoms. And once a person shows symptoms, they are quarantined or hospitalized, meaning it becomes harder to spread. According to Stephen Morse, an epidemiologist at Columbia University, “almost all of the transmission of SARS was within the health care setting. […] you could control SARS by improving infection control and prevention in the hospitals.” Ultimately, SARS mysteriously disappeared. The virus was aggressive and lethal, but strict quarantine measures fought the threat. By July of 2003, WHO declared the pandemic over. 

On the other hand, COVID spreads extremely easily from person to person. Casual interactions are enough for COVID to spread, and pre-symptomatic transmission causes numbers to climb through people who are unaware of the fact that they are infected at all! Virology professor John Oxford believes the two viruses are very different: “We were very lucky in this regard with SARS in 2003. It was nothing like as spreadable as the COVID-19 coronavirus. […] in the end [SARS] ran out of people to infect, it just ran out of steam.”

COVID is also changing the future for science, especially related to vaccines. The fastest any vaccine had been developed was four years, but this past December, the Pfizer vaccine became the first immunization approved for emergency use. 

SARS in this aspect is much different. In November of 2003, WHO predicted a vaccine would take between two to five years to develop. However, as isolation and quarantine measures proved to be enough to contain the virus, a vaccine for SARS was never made. Dr. Atmar, a professor at Baylor College of Medicine, explains: “To bring a vaccine all the way through clinical development and licensure, it’s going to cost tens, if not hundreds, of millions of dollars.” Because the public health system effectively contained the pandemic, the virus was virtually eradicated without a vaccine. For COVID, it is clear that there is a need for the vaccine, and that the pandemic will not end in a timely manner without the use of the vaccine. 

As diseases, both SARS and COVID share certain characteristics. Transmission occurs through respiratory droplets, risk factors include old age and underlying conditions, and both have the same enzyme (ACE2) that acts as a receptor for the virus to enter a cell. But the pandemic trajectories are immensely different. SARS was contained in a span of eight months, but COVID may last for years.