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Last reviewed
November 5, 2021

Coronavirus Overview

Human coronaviruses were cultured in the 1960s from nasal cavities of people with the common cold, reported a recent study. Coronaviruses are the 2nd leading cause of the common cold after rhinoviruses

People commonly get infected with human coronaviruses 229E, NL63, OC43, and HKU1, says the U.S. CDC.

The International Committee for the Taxonomy of Viruses approved the naming of more than 40 coronaviruses. There are four main sub-groupings of coronaviruses, known as alpha, beta, gamma, and delta. Betacoronaviruses are microscopic balls covered in spikes that encapsulate a central core of genetic material. The virus must infect cells to replicate and do this, and it must first attach to the cells.

Both the Middle East Respiratory Syndrome (MERS) and Severe Acute Respiratory Syndrome (SARS) are betacoronavirus and have their origins in bats. Additionally, MERS (ongoing) and SARS-1 (2003) have been known to cause severe illness in humans.

On January 9, 2020, China's CDC reported a novel coronavirus as the causative agent of the COVID-19 outbreak. This novel coronavirus has been named 'severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), while the human disease it causes has been classified by the WHO as COVID-19.

SARS-CoV-2 Coronavirus

The CDC reported SARS-CoV-2 originated in 2019 but has now spread internationally, impacting most countries.

On February 5, 2020, JAMA published a study from genetic sequencing data, showing this betacoronavirus shares 79.5% of the genetic sequence with SARS-CoV-1 and has 96.2% homology to a bat coronavirus. This finding indicates SARS-CoV-1 and SARS-CoV-2 are not the same coronaviruses.

SARS-CoV-1 Coronavirus

SARS-CoV-1 was the first significant novel infectious disease to hit the international community in the 21st century, says the U.S. CDC. SARS was first reported in Asia in February 2003 and became a notifiable disease in mid-April in central China. By the time the outbreak was contained in July 2003, SARS had affected 8,098 people in 29 countries and resulted in 774 deaths, reported GAVI.

MERS-CoV Coronavirus

The emergence of the betacoronavirus Middle East Respiratory Syndrome (MERS) was first reported in the Kingdom of Saudi Arabia in 2012. Humans are infected with MERS-CoV from direct or indirect contact with dromedaries. In addition, MERS-CoV has demonstrated the ability to transmit between humans. So far, the observed non-sustained human-to-human transmission has occurred mainly in healthcare settings, says the WHO.

SARS-CoV-2 Reinfection

A study published on October 1, 2021, 'reinfection by SARS-CoV-2: a comparative evolutionary survey. Interpretation - As the COVID-19 pandemic continues, reinfection is likely to become increasingly common. Reinfection by SARS-CoV-2 under endemic conditions would likely occur between 3 months and 5.1 years after peak antibody response, with a median of 16 months. This protection is less than half the duration revealed for the endemic coronaviruses circulating among humans (5–95% quantiles 15 months to 10 years for HCoV-OC43, 31 months to 12 years for HCoV-NL63, and 16 months to 12 years for HCoV-229E). For SARS-CoV, the 5–95% quantiles were four months to 6 years, whereas the 95% quantiles for MERS-CoV were inconsistent by dataset.

Relevant Coronavirus Links

Note: This content is sourced from the U.S. CDC, the WHO, research studies, and is reviewed by health professionals, such as Dr. Robert Carlson.