SARS-CoV-2

Authored by
Staff
Last reviewed
October 14, 2021

SARS-CoV-2 Coronavirus

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

However, it is not the same virus. The SARS-CoV-2 coronavirus is similar to MERS-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 several weeks before the first genome sequenced in China, known as Wuhan-1, stated Sayaka Miura, a study's senior author.

SARS-CoV-2 Virus Transmission

On May 7, 2021, the WHO stated 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.'

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.

A new study published by Clinical Infectious Diseases on August 6, 2021, confirmed SARS-CoV-2 is most often spread via aerosol particles when people cough, speak or sing when inside a room. Furthermore, the risk of the SARS-CoV-2 virus spreading from animals to people is considered low, says the CDC

SARS-CoV-2 Reinfection and 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, CD4+ T cells, and/or 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 a SARS-CoV-2 infection.

On September 2, 2021, The JAMA Network published a CDC study that estimated 83.3% of people in the USA had combined infection- and vaccine-induced antibodies in May 2021. And the Public Health England reported in October 2021, about 98% of tested people have some form of SARS-CoV-2 immunity.

An updated listing of studies focused on vaccine-generated and post-infection immunity is published at this link.

SARS-CoV-2 Variants

The coronavirus that causes COVID-19 is mutating, and that's to be expected. Many viruses mutate as they spread worldwide, 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. After that, V and G strains were followed by Strain G mutated yet further into strains G.R., G.H., and G.V. Several other infrequent mutations were collectively grouped as strain O. The most recent mutation to emerge is the G.V. strain, isolated to Europe, becoming increasingly common.

On March 15, 2021, a U.S. 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. In addition, on May 31, 2021, the WHO assigned labels for key variants of SARS-CoV-2 using letters of the Greek alphabet.

On August 6, 2021, the U.K. reported the Delta variant accounted for approximately 99% of sequenced and 98% of genotyped cases from 25 July to 31 July 2021. And the U.K. Genotype to Phenotype Consortium reports new data relating to Lamba (VUI21JUL-01 (B.1.621). In addition, there is evidence of a reduction in pseudovirus neutralization by serum from individuals who have been vaccinated or previously infected with Delta.

A non-peer-reviewed study published on September 12, 2021, found that spike S1 is a focal point of adaptive evolution and identifies positively selected mutations in other genes that sculpt the evolutionary trajectory of SARS-CoV-2. In addition, protein-coding mutations in S1 are temporally clustered. In 2021, the non-synonymous to synonymous divergence ratio in S1 is more than four times greater than in the equivalent influenza HA1 subunit.

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 has 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 Detection in Wastewater

State health departments in the USA have used wastewater data to allocate testing resources, evaluate possible irregularities in traditional surveillance, refine health messaging, and forecast clinical resource needs at the community level, says the CDC.

As of August 2021, 43 public health departments are using CDC funds to support wastewater surveillance activities, 32 state and local health departments are participating in the public health community of practice, and nine states are reporting data to NWSS. SARS-CoV-2 RNA is quantified using PCR technology, either reverse transcription-quantitative PCR (RT-qPCR) or reverse transcription droplet digital PCR (RT-ddPCR).

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. Furthermore, an analysis found samples taken in Milan and Turin on December 18, 2020, showed the SARS-CoV-2 virus.

Wastewater-based surveillance of SARS-CoV-2 has been adopted in Finland as an indicator for local and national COVID-19 incidence trends. 

SARS-CoV-2 Historical Research

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 SARS-CoV-2 caused the first case of COVID-19 between early October and mid-November 2019 in China.

The U.S. House Foreign Affairs Committee Minority Staff has continued to investigate the origins of COVID-19, examining new information as it became available, including through expert testimony. On August 1, 2021, based on the material collected and analyzed by the Committee Minority Staff, the preponderance of evidence suggests SARS-CoV-2 was accidentally released from a Wuhan Institute of Virology laboratory sometime before September 12, 2019. The virus, or the viral sequence that was genetically manipulated, was likely collected in a cave in Yunnan province, PRC, between 2012 and 2015.

In June 2021, the journal Nature published an article examining arguments that the coronavirus SARS-CoV-2 escaped from a lab in China and the science behind it.

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 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 U.S. case on Jan 21, 2020.

In March 2018, ECOHealth Alliance sought DARPA funding for Project DEFUSE to investigate SARS-related spillover potential in certain bat populations in China, and SARSr-CoV shedding in cave bats, reported Newsweek on September 22, 2021. Specific work would be subcontracted to Duke, North Carolina, and other research entities. DARPA was reported to have rejected the proposal.

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 U.S. 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, these researchers said a 1% nasal rinse solution inactivated HCoV greater than 99.9% with a 2‐min contact time. 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 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% M.B. 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.