SARS-CoV-2

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Staff
Last reviewed
July 7, 2021

SARS-CoV-2 Coronavirus

The novel coronavirus Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) was identified in China in 2019, reported the World Health Organization (WHO). As the name indicates, the virus is related to the SARS coronavirus (SARS-CoV) that caused deadly outbreaks in 2002-2003.

However, it is not the same virus. The SARS-CoV-2 virus is a beta coronavirus, similar to MERS-CoV and SARS-CoV.

In the field of molecular epidemiology, a study published on May 4, 2021, found the progenitor genome (proCoV2) is the mother of all SARS-CoV-2 coronaviruses. These researchers estimate that the SARS-CoV-2 progenitor was in circulation at least 6 to 8 weeks before the first genome sequenced in China, known as Wuhan-1. "This timeline puts the presence of proCoV2 in late October 2019, which is consistent with the report of a fragment of spike protein identical to Wuhan-1 in early December 2019 in Italy, among other evidence," said Sayaka Miura, a senior author of the study.

On June 24, 2021, David Roberts of the University of Kent, U.K., and colleagues present in the journal PLOS Pathogens, a new analysis suggests that the first case of COVID-19 arose between early October and mid-November 2019 in China.

SARS-CoV-2 Transmission

On May 7, 2021, the 'principal mode by which people are infected with SARS-CoV-2 coronavirus is exposure to respiratory fluids carrying the infectious virus. Exposure occurs in three principal ways: (1) inhalation of very fine respiratory droplets and aerosol particles, (2) deposition of respiratory droplets and particles on exposed mucous membranes in the mouth, nose, or eye by direct splashes and sprays, and (3) touching mucous membranes with hands that have been soiled either directly by virus-containing respiratory fluids or indirectly by touching surfaces with the coronavirus on them.'

SARS-CoV-2 Reinfection Immunity

A study funded by the U.S. NIH reviewed the duration of immunological memory after SARS-CoV-2 infection. Immunological memory can consist of memory B cells, antibodies, memory CD4+ T cells, and/or memory CD8+ T cells. These researchers concluded: 'Substantial immune memory is generated after COVID-19, involving all four major types of immune memory. About 95% of subjects retained immune memory at ~6 months after infection. Circulating antibody titers were not predictive of T cell memory. Thus, simple serological tests for SARS-CoV-2 antibodies do not reflect the richness and durability of immune memory to SARS-CoV-2. This work expands our understanding of immune memory in humans. These results have implications for protective immunity against SARS-CoV-2 and recurrent COVID-19.'

SARS-CoV-2 Variants

The coronavirus that causes COVID-19 is mutating, and that's to be expected. Many viruses mutate as they spread throughout the world, stated the U.S. CDC on December 22, 2020.

The original SARS-CoV-2 strain, detected in Wuhan's city, China, in December 2019, is the L virus strain. The virus then mutated into the S strain at the beginning of 2020. V and G strains were followed by Strain G mutated yet further into strains GR, GH, and GV. Several other infrequent mutations were collectively grouped as strain O. The most recent mutation to emerge is the GV strain, isolated to Europe, becoming increasingly common.

On March 15, 2021, a US government interagency group announced a Variant Classification scheme that defines three classes of SARS-CoV-2 variants: Variant of Interest; Variant of Concern, Variant of High Consequence. The B.1.1.7, B.1.351, P.1, B.1.427, and B.1.429 variants circulating in the USA are classified as Variants of Concern. These variants share one specific mutation called D614G, first documented in the USA in the initial stages of the COVID-19 pandemic in 2020.

Researchers identified 484 unique mutations among six strains of SARS-CoV-2 isolates early in the COVID-19 pandemic in Ohio. Within weeks of SARS-CoV-2 circulation, a profound shift toward 23403A>G (D614G) specific genotypes occurred. Replaced clades were associated with worse clinical outcomes, including mortality. This study was published in JAMA on April 26, 2021.

On May 12, 2021, the CDC published an Update on Emerging SARS-CoV-2 Variants and Vaccine Considerations. In addition, on May 31, 2021, the WHO assigned labels for key variants of SARS-CoV-2 using letters of the Greek alphabet.

SARS-CoV-2 Symptoms

People infected with this new beta coronavirus have reported a wide range of symptoms – ranging from mild symptoms to severe illness - often appearing 2-14 days after exposure to the SARS-CoV-2 virus, says the U.S. CDC.

Specifically, studies published in JAMA on June 18, 2020, and in PLOS on October 1, 2020, found that the loss of taste and smell may be common symptoms among those in the early stages of SARS-CoV-2 coronavirus infection. And the seropositivity for the SARS-CoV-2 virus was 3 times more likely in study participants with smell loss (OR 2.86; 95% CI 1.27–6.36; p < 0.001) than those with taste loss.

SARS-CoV-2 Diagnostic Tests

The COVID-19 tests most people discuss are RT-PCR, the nasal-swab test that detects viral RNA, and various antibody tests that see if you have an immune response due to past exposure to the SARS-CoV-2 virus. The first SARS-CoV-2 test kits under a EUA were distributed on February 7, 2020, reported the U.S. FDA.  As of June 29, 2021, the FDA announced it had authorized 389 coronavirus diagnostic tests. For updated coronavirus test news, please visit 'Tests.'

On May 27, 2021, the U.S. FDA Center for Devices and Radiological Health issued a report that describes the approaches used by the South Korean government to address COVID-19, particularly regarding the development, authorization, and use of diagnostic tests. South Korea took on SARS-CoV-2 testing earlier than most countries. South Korea’s approach was based on lessons learned from an outbreak of Middle Eastern Respiratory Syndrome (MERS) in 2015. Since 2017, South Korea’s Ministry of Science and Information and Communications Technology invested in the commercial development of diagnostic tests for infectious diseases by investing almost US$25 million in infectious disease diagnostic technology. Later, the Korea Disease Control and Prevention Agency established a testing capability in selected laboratories to conduct clinical studies and evaluate commercial manufacturer tests. South Korea also stockpiled testing supplies, such as swabs. By the end of February 2020, South Korea offered drive-through screening centers and the ability to test thousands of people daily, reported Reuters.

SARS-CoV-2 Transmission Patterns

Based on what is currently known about this coronavirus, the transmission occurs commonly through respiratory droplets. The virus spread from person to person happens most frequently among close contacts living together. The SARS-CoV-2 virus appears to spread more efficiently than influenza, but not as efficiently as measles, which is highly contagious, says the CDC.

A non-peer-reviewed study reported cells of the salivary glands, tongue, and tonsils carry the most RNA linked to proteins (ACE2 receptor) that coronavirus needs to infect cells. Saliva from SARS-CoV-2-infected individuals harbored epithelial cells exhibiting ACE2 expression and SARS-CoV-2 RNA.

Furthermore, the risk of the SARS-CoV-2 virus spreading from animals to people is considered low, says the CDC

SARS-CoV-2 Reinfection Rate

Public Health England (PHE) published population surveillance data on possible coronavirus reinfections on June 17, 2021. There were 15,893 possible reinfections with SARS-CoV-2 identified up to May 2021 in England throughout the COVID-19 pandemic, out of nearly 4 million people with confirmed infections. This PHE data is equivalent to 0.4% of SARS-CoV-2 infections becoming reinfected.

SARS-CoV-2 Detection in Wastewater

The U.S. EPA says, 'Preliminary research from across the country and around the world indicates that monitoring wastewater for the presence of the genetic marker of SARS-CoV-2, its RNA, may be useful as a sensitive early indicator of low levels of infections in the community.' Study results highlight the unpredictable dynamics that characterized the earliest days of the COVID-19 pandemic. Even though all of the earliest documented cases of COVID-19 were found in Hubei province, China, research cannot discount the possibility that the index case initially acquired the virus elsewhere.

Researchers from the Spanish university of Burgos and the Federal University of Santa Catarina in Brazil have jointly led a study that detected SARS-CoV-2 in wastewater in Brazil as early as November 2019. And the Italian National Institute of Health looked at sewage samples collected from wastewater treatment plants in northern Italy between October 2019 and February 2020. An analysis found samples taken in Milan and Turin on December 18, 2020, showed the presence of the SARS-CoV-2 virus.

SARS-CoV-2 Detection in Blood Donations

A study published by Clinical Infectious Diseases on November 30, 2020, concluded saying 'These findings suggest that SARS-CoV-2 may have been introduced into the United States before January 19, 2020.'

The American Red Cross published the following statement on December 1, 2020, 'The findings of this study indicate that it is possible the coronavirus that causes COVID-19 may have been present in California, Oregon, and Washington as early as Dec. 13-16, 2019, and in Connecticut, Iowa, Massachusetts, Michigan, Rhode Island, and Wisconsin as early as Dec. 30, 2019 - Jan. 17, 2020. Researchers at the CDC found antibodies that reacted to the virus in blood donations from all nine states that were part of this study. A previous survey of blood donors, conducted to help understand travel practices, determined that less than 3% of respondents reported travel outside of the U.S. within the 28 days before donation. Of those reporting travel, only 5% traveled to Asia.'

A U.S. National Institutes of Health analysis published on June 15, 2021, of more than 24,000 stored blood samples reveals SARS-CoV-2 antibodies in nine participants in five states as early as Jan 7, 2020, indicating that COVID-19 was in the country weeks before the CDC announced the first US case on Jan 21, 2020.

SARS-CoV-2 Sunlight and Swimming

The U.S. CDC stated 'evidence suggests that the SARS-CoV-2 virus cannot be spread to humans through most recreational water.'

On June 12, 2020, the US Department of Homeland Security Science and Technology (S&T) Directorate added a calculator that estimates the natural decay of the SARS-CoV-2 virus in the air, such as when visiting a breach found the coronavirus was least stable in the presence of sunlight. This new S&T research has been featured in the Oxford Academic Journal of Infectious Diseases, with the most recent – Airborne SARS-CoV-2 is Rapidly Inactivated by Simulated Sunlight.

SARS-CoV-2 Oral Infection Prevention

According to a study published on September 17, 2020, nasal rinses and mouthwashes directly impact the major sites of reception and transmission of human coronaviruses (HCoV), which may provide an additional protection level against the virus. Common over‐the‐counter nasal rinses and mouthwashes - gargles were tested for their ability to inactivate high concentrations of HCoV using contact times of 30 s, 1 min, and 2 min. For example, a 1% nasal rinse solution inactivated HCoV greater than 99.9% with a 2‐min contact time, said these researchers. According to Penn State College of Medicine researchers, various OTC products might be useful for reducing the viral load, or amount of virus, in the mouth after infection.

On October 30, 2020, a Letter to the Editor discussed methylene blue as an anti-COVID-19 mouthwash in dental practice. In the case of SARS-CoV-2, the salivary gland could be a major source of the virus in saliva (Liu et al.). Therefore, 'we suggest repeated use of mouth wash every five to ten minutes during dental procedures to decrease the viral load of freshly secreted saliva. Based on the data, 0.5% MB oral rinse therapy appears to be a potentially effective preprocedural mouthwash in dental practice.

SARS-CoV-2 Coronavirus FAQs

NOTE: This page's content is sourced from the CDC, WHO, clinicaltrials.gov, and the Precision Vax network of websites. This information was fact-checked by healthcare providers, such as Dr. Robert Carlson.