The Potential for a SARS 3
Coronavirus is a diverse category of viruses, to which the novel coronavirus is but the latest addition. These viruses are named for their crown-shaped form, which comes from a series of spindly projections that emerge from the virus’s surface. Most often, these viruses are present in animals such as bats, which may pass them along to humans if the virus mutates [1]. The virus that causes COVID-19 causes severe acute respiratory syndrome, lending it the name SARS-CoV-2. Whether a SARS 3 will emerge remains to be seen, but lessons and research from past experience should accelerate future efforts toward prevention and treatment.
The first coronavirus outbreak that caused severe acute respiratory syndrome (SARS-CoV) came in 2002. Widely known as SARS, this virus originated from bats and spread quickly to humans. Like the new coronavirus (SARS-CoV-2), the original SARS virus targeted ACE-2 receptors and was transmitted through droplets passed from one individual to another. However, the fatality and transmission rates for SARS-CoV-2 are more than three times that of the original SARS virus [2]. Several other coronaviruses emerged between the original SARS outbreak and the outbreak of SARS-CoV-2 in late 2019, though most only cause mild cold-like symptoms.
The timing of an outbreak of a new SARS-related coronavirus (presumably titled SARS-CoV-3) is impossible to predict. Most likely, it will originate in bats or other animals, which will then pass it to humans. The degree to which it will affect the human hosts and how fast it spreads are difficult to ascertain. However, both the speed by which it is contained and the speed of vaccine production are within our control.
Both SARS and COVID-19 can provide useful lessons on the need for quick containment. In the case of SARS, inadequate public surveillance allowed the virus to spread unchecked. Once systems were put in place to quarantine affected individuals and stop international transit, the virus was able to be contained [3]. The virus that causes COVID-19 was quickly identified, and the genome sequenced within two weeks of the first reported case [4]. However, the shape of the spike proteins on the SARS-CoV-2 virus bind 10 times more tightly than that of the SARS-CoV virus, greatly speeding up its ability to infect hosts [5]. Nonetheless, the implementation of early warning systems and fast sequencing can help to identify a future strain and contain its spread.
If a new coronavirus were to develop into a pandemic, new advancements in vaccine development during the COVID-19 pandemic would likely lead to the quick development of a vaccine. The newest vaccines for SARS-CoV-2 use mRNA instead of inactivated or weakened agents that resemble the disease-causing microorganism. These vaccines can be developed rapidly and have exceptionally high efficacy rates. Indeed, the BNT162b2 mRNA vaccine was found to be 95% effective in preventing COVID-19 [6]. If a SARS 3 were to emerge, mRNA could likely be used to quickly produce highly effective vaccines.
There are signs that SARS-CoV-2 is mutating—in December, the U.K. reported that a new, highly transmittable strain had been identified. The new strain does not appear to be more dangerous, and most mRNA vaccines are still expected to work on the new variant. However, future mutations may make it difficult for certain drugs, including Regeneron’s antibody treatment, to remain effective [7]. While this development warrants caution and investigation, it does not mean that a new SARS virus has emerged—instead, this is simply a mutation of the existing virus.
References
[1] Zhu, Zhixing, et al. “From SARS and MERS to COVID-19: A Brief Summary and Comparison of Severe Acute Respiratory Infections Caused by Three Highly Pathogenic Human Coronaviruses.” Respiratory Research, vol. 21, no. 1, 2020, doi:10.1186/s12931-020-01479-w.
[2] Ceccarelli, M, et al. “Differences and Similarities between Severe Acute Respiratory Syndrome (SARS)-CoronaVirus (CoV) and SARS-CoV-2. Would a Rose by Another Name Smell as Sweet?” European Review for Medical and Pharmacological Sciences, vol. 24, no. 5, 2020, pp. 2781–2783., doi:10.26355/eurrev_202003_20551.
[3] Heymann, David L. “The International Response to the Outbreak of SARS in 2003.” Philosophical Transactions of the Royal Society B, vol. 359, no. 1447, 2004, pp. 1127–1129., doi:10.1098/rstb.2004.1484.
[4] Lisa Schnirring | News Editor | CIDRAP News | Jan 11, 2020. “China Releases Genetic Data on New Coronavirus, Now Deadly.” CIDRAP, 11 Jan. 2020, www.cidrap.umn.edu/news-perspective/2020/01/china-releases-genetic-data-new-coronavirus-now-deadly.
[5] Wrapp, Daniel, et al. “Cryo-EM Structure of the 2019-NCoV Spike in the Prefusion Conformation.” Science, vol. 367, no. 6483, 2020, pp. 1260–1263., doi:10.1126/science.abb2507.
[6] Polack, Fernando P., et al. “Safety and Efficacy of the BNT162b2 MRNA Covid-19 Vaccine.” New England Journal of Medicine, vol. 383, no. 27, 2020, pp. 2603–2615., doi:10.1056/nejmoa2034577.
[7] Starr, Tyler N., et al. “Prospective Mapping of Viral Mutations That Escape Antibodies Used to Treat COVID-19.” bioRxiv, 2020 (preprint), doi:10.1101/2020.11.30.405472.