Coronavirus (SARS CoV-2)

If you head over to the main History of Vaccines site, you’ll see that we have an Articles section where information on the known vaccine-preventable diseases is posted. In the last few years, two more vaccines have been authorized for use against their respective diseases: Ebola and Coronavirus. In this blog post, you will get a preview of the information that will soon be posted on the Coronavirus, albeit in a slightly different format than it is on the Articles section.


In late 2019, the government of the People’s Republic of China (“China”) reported a cluster of cases of pneumonia in Wuhan, Hubei Province. The cases were centered around a market in town, and the pathogen causing the disease was not well understood. While some suggested it was a respiratory virus, other pathogens were also candidates. When that announcement was made, multiple international agencies moved to aid the government of China in the investigation and control of the disease.

By early January 2020, the World Health Organization issued a series of advisories on the pneumonia cluster. However, by mid-January, the first cases of the disease started to be reported outside of Thailand. By then, epidemiologists agreed worldwide that the pathogen was transmissible from person to person and that it had eluded containment. Around the same time, the government of China shared the genetic sequence of a coronavirus recovered from multiple patients in the cluster.

The coronavirus was classified as Severe Acute Respiratory Syndrome (SARS) – Coronavirus 2 (CoV-2), and it was declared the causative agent of Coronavirus Disease 19 (COVID-19), with “19” signaling the year of the beginning of the disease. This was the second SARS coronavirus causing disease in humans and the seventh known coronavirus overall to cause human disease. The first four human coronaviruses are what epidemiologists call “nuisance viruses” because they only cause severe disease in a small number of people and are not known to cause epidemics of serious disease. In 2003, the first SARS virus caused a series of epidemics in Asia, North America and Europe. While it was close to causing a pandemic, that virus was not adapted to causing large epidemics. By the end of 2003, the epidemics ended with about 800 known deaths.

In 2012, a novel coronavirus was detected in patients who had traveled to the Middle East. The virus, called Middle East Respiratory Syndrome (MERS) virus, also triggered regional epidemics with a low number of cases and low number of deaths. Like SARS in 2003, MERS was not adapted to go from person to person, and the epidemics were over in six months.

Historically, coronaviruses have been known since the 1960s when teams of scientists reported isolating viruses from respiratory secretions in animals and humans. When seen under the microscope, the virus particles seemed to have a series of protrusions on their surface that resembled the corona of a star. (“Corona” is the Latin term for crown.) From time to time, coronaviruses may cause small, localized and limited epidemics of disease, like an epidemic of respiratory disease in Tecumseh, Michigan.

The publishing of the genetic sequence of SARS CoV-2 allowed scientists around the world to collaborate toward the understanding of COVID-19 and toward a vaccine that could help halt the then-developing pandemic. At the time of the announcement of the Wuhan epidemic, vaccines developed to counter SARS and MERS had been researched but not developed. Nevertheless, that research from years past was put to work on a vaccine against the new coronavirus. At the beginning of the pandemic, the following options for vaccines were available:

  • A killed (inactivated) virus vaccine
  • An attenuated virus vaccine
  • A subunit vaccine
  • A viral vector vaccine
  • An mRNA vaccine

In the United States, two mRNA vaccine candidates quickly moved through their clinical trials with help from the immense amount of money provided through Operation Warp Speed, a US government program that aimed to fund vaccine development and distribution. With those funds, vaccine manufacturers were able to work in parallel through their research toward a vaccine candidate and testing; instead of doing each step sequentially, which would have been time-consuming. A third vaccine candidate, a viral vector vaccine, moved a little slower through its trials, but it would go to market shortly after the two mRNA vaccines.

In other parts of the world, vaccine developers were also racing toward a safe and effective vaccine while making use of billions of dollars in funding from different world governments and international agencies. In Russia, a viral vector vaccine was developed and allowed for use in August 2020, making it the first vaccine permitted to be used. Other vaccines followed soon thereafter. By December 2020, the two mRNA vaccines gained Emergency Use Authorization in the United States, with the viral vector joining them in February 2021.

For more information on what vaccines are currently allowed in the United States and the rest of the world, see this ever-expanding and up-to-the-minute page from The New York Times: https://www.nytimes.com/interactive/2020/science/coronavirus-vaccine-tracker.html

Read More:

Listings of WHO’s Response to COVID-19: https://www.who.int/news/item/29-06-2020-covidtimeline

Covid-19 Vaccines, The New York Times: https://www.nytimes.com/spotlight/coronavirus-vaccine 

Emergency Use Authorization, Food and Drug Administration: https://www.fda.gov/emergency-preparedness-and-response/mcm-legal-regulatory-and-policy-framework/emergency-use-authorization

Author: René F. Najera, DrPH

I am the editor of the History of Vaccines site, an online project by the College of Physicians of Philadelphia. All opinions expressed on these blog posts are not necessarily those of the College or any of my employers. Check out my professional profile on LinkedIn: https://www.linkedin.com/in/renenajera Feel free to follow me on Twitter: @EpiRen