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May 12, 2021

SARS-CoV-2 Coronavirus

In December 2019, the novel coronavirus Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) was identified in China. 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 prior to 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.

SARS-CoV-2 Transmission

The U.S. CDC stated on May 7, 2021, the 'principal mode by which people are infected with SARS-CoV-2 coronavirus is through exposure to respiratory fluids carrying 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 Variants

The coronavirus that causes COVID-19 is mutating, and that's to be expected. As they spread throughout the world, many viruses mutate, 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, which has so far been isolated to Europe, where it has become 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, which was 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.

As of April 27, 2021, the U.S. CDC reported the number of variant cases on this website.

On May 12, 2021, the CDC published an Update on Emerging SARS-CoV-2 Variants and Vaccine Considerations.

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) compared with 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. For updated news, please visit 'Tests.'

SARS-CoV-2 Transmission Patterns

Based on what is currently known about this coronavirus, the transmission occurs much more 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.

MIT professors proposed in the journal PNAS on April 15, 2021, a new approach to estimating a person's risks of exposure to the SARS-CoV-2 virus that causes COVID-19 under different indoor settings. The new MIT guideline suggests a limit for exposure time, based on the number of people, the size of the space, the kinds of activity, whether masks are worn, and the ventilation and filtration rates. This MIT model offers a detailed, physics-based guideline for policymakers, businesses, schools, and individuals to gauge their own risks.

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

SARS-CoV-2 Sunlight and Swimming

The U.S. CDC stated 'evidence suggests that the SARS-CoV-2 virus that causes COVID-19 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, and 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 and Preventions

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. 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 facts, diluted MB appears to be a potentially effective preprocedural mouthwash in dental practice. 0.5% MB oral rinse therapy has already yielded results as a potent, safe, and cost-effective alternative to other mouthwashes.

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 the presence of SARS-CoV-2 in wastewater in Brazil as early as November 2019.

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 Coronavirus FAQs

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