When COVID-19 first appeared in the news, scientists took note and began to prepare for a widespread outbreak. The general population, however, wasn’t concerned. Many assumed it would be like the SARS pandemic, affecting relatively few people and, aside from a few cities or regions, not disrupting daily life.
They can be forgiven for thinking that.
Severe acute respiratory syndrome (SARS) appeared in 2002 and quickly spread around the world. The Centers for Disease Control (CDC) reported that 8,098 people were infected in 26 countries, and that 774 died. (Other sources report slightly different numbers.)
SARS was called the first pandemic of the 21st century. It would not be the last. Nor would it be the most deadly.
Since Chinese officials first reported the COVID-19 outbreak in Wuhan December 31, 2019, the virus has spread to 206 countries. By about 5 p.m. PST on April 1, Johns Hopkins University reported a steadily-climbing global infection rate of 719,669, with 42,075 deaths.
There are seven variants of coronavirus known to infect humans. SARS and COVID-19 are the most closely-related versions. Four are common and are relatively benign: 229E, NL63, OC43 and NKU1.
The remaining three, however, have wreaked global havoc. MERS-CoV, causes Middle East Respiratory Syndrome (MERS). SARS-CoV causes SARS. SARS-CoV-2 causes COVID-19. These three can infect animals, evolve and re-infect humans, becoming a new virus.
SARS’ symptoms typically began with a high fever and dry cough, followed by shortness of breath and diarrhea. Severe cases often progressed rapidly to pneumonia, requiring hospitalization and often intensive care.
COVID-19 symptoms are similar. They typically feature fever, cough and shortness of breath. Severe cases include respiratory distress that may require hospitalization and the use of ventilators.
Initially, SARS and COVID-19 viruses both jumped from animals to humans. Horseshoe bats have been implicated in SARS and again in COVID-19. As the World Health Organization (WHO) stated in a February 2020 report, “Bats appear to be the reservoir of COVID-19 virus.”
In 2002, these bats were sold in China’s wet markets – places where live animals were sold for food. The SARS outbreak occurred in Guangdong province and has been linked to its wet markets. By 2019, horseshoe bats were no longer sold in the wet markets.
Nor do they live in the wild near Wuhan. As Chinese researcher Huabin Zhao, Department of Ecology, Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Wuhan University pointed out in Science, “COVID-19 was linked to horseshoe bats, which do not hibernate in cities in China.” They are used in biomedical research, however, and Wuhan, the city in which COVID-19 originated, has two such labs.
Researchers investigating the virus’s origins speculate a scientist might have been bitten by a bat and became infected.
Once SARS jumped to humans, it was transmitted from person to person. It is most virulent during the second week of infection when virus excretions through the mucus and stool peak.
With SARS, most human-to-human infections occurred in health care settings that lacked robust infection control procedures. When infection control practices were implemented, the outbreak ended. Since then, the only occurrences have occurred through laboratory accidents. They have not spread throughout the community.
COVID-19 appears to spread person-to-person, through droplets that are expelled when a person coughs or sneezes and then are inhaled by a nearby person. Less often, it may be spread by touching an infected surface and then touching one’s mouth, nose, or eyes. Transmission may also occur before a person becomes symptomatic. As the CDC cautions, “COVID-19 is a new disease and we are still learning how it spreads.”
Although the persistence of COVID-19 and SARS varies, its was similar enough to consider them comparable, according to researchers working with the National Institute of Allergy and Infectious Diseases, reporting in the New England Journal of Medicine (NEJM). They compared the persistence of the SARS-CoV-2 (COVID-19) and SARS-CoV-1 (SARS) viruses for aerosols, plastic, stainless steel, copper and cardboard.
Specifically, for Covid-19, no viable quantities of COVID-19 remained on copper after four hours or on cardboard after 24 hours. For SARS, the time periods beyond which no viable virus remained on copper and cardboard were each eight hours.
“Our results indicate that aerosol and fomite (objects that may carry infection) transmission of SARS-CoV-2 (COVID-19) is plausible since the virus can remain viable and infectious in aerosols for hours and on surfaces up to days,” they wrote in a letter to the NEJM.
Diagnostics, Vaccines and Therapeutics
When SARS and COVID-19 were first reported, no diagnostics, vaccines or therapeutics were available. Both viruses were completely new in humans.
By early April 2003, when the SARS epidemic was in full swing, the WHO announced setbacks in efforts to develop a diagnostic test. Of the three then in development, one was unreliable and two could only be used late in the course of the illness.
Development has moved much faster for COVID-19 tests. By April 2020, diagnostics tests already were in the hands of medical professionals, and time to diagnosis was dropping from days to less than an hour. More than 40 biopharma companies in the U.S. alone are racing to develop active and passive vaccines as well as therapeutics. Moderna, for example, plans to begin clinical trials in June. Emergent BioSolutions hopes to launch Phase II trials in August or September. Others are planning for later this year or early 2021.
The SARS pandemic was short-lived. Only eight months separated the first reported case (November 2002) to the end of the crisis in July 2003.
No one can accurately project the duration of the COVID-19 pandemic. That largely depends upon the success of social distancing. So far, two thirds of U.S. states have mandatory stay-at-home orders in place. Others are enacting them and many are extending existing orders’ duration. Virginia’s just-enacted order is one of the longest. It will be in place through June 10.