During 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.
On February 5, 2020, JAMA published a study focused on genetic sequencing data, found the SARS-CoV-2 coronavirus shares 79.5% of the genetic sequence with SARS-CoV and has 96.2% homology to a bat coronavirus.
People infected with this new betacoronavirus 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 Transmission Patterns
Based on what is currently known about this coronavirus the transmission occurs much more commonly through respiratory droplets than through fomites. 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.
The virus spread from person-to-person happens most frequently among close contacts, living together at home, or a nursing facility.
On October 5, 2020, the CDC published a website change which states 'There is evidence that under certain conditions, people with COVID-19 seem to have infected others who were more than 6 feet away. These transmissions occurred within enclosed spaces that had inadequate ventilation. Sometimes the infected person was breathing heavily, for example, while singing or exercising.'
'This kind of spread is referred to as 'airborne transmission' and is an important way that infections like tuberculosis, measles, and chickenpox are spread.'
'Under these circumstances, scientists believe that the amount of infectious smaller droplets and particles produced by the people with COVID-19 became concentrated enough to spread the virus to other people,' says the CDC.
A study published in Emerging Infectious Diseases on June 23, 2020, suggests that SARS-CoV-2 generally maintains infectivity at a respirable particle size over short distances, in contrast to either betacoronavirus, SARS-1, and MERS. And, current evidence suggests that SARS-CoV-2 can remain viable for several hours on surfaces made from a variety of materials.
Cleaning dirty surfaces followed by disinfection is the best measure to prevent respiratory illnesses in community settings. And, SARS-CoV-2 was more stable on plastic and stainless steel, than on copper and cardboard.
A study published by Clinical Infectious Disease on October 3, 2020, indicates the SARS-CoV-2 coronavirus survives on human skin for up to 9 hours. This extended survival time on human skin may increase the contact-transmission risk of SARS-CoV-2 compared to other viruses. However, these researchers found appropriate hand hygiene is highly effective at neutralizing the coronavirus. SARS-CoV-2 found in the mucus/medium on human skin were completely inactivated within 15-seconds by ethanol treatment.
On November 10, 2020, the CDC published a virus transmission review that found up to 70% of fine particles could be reduced by wearing face masks when inside. No data was disclosed regarding the benefits of wearing a face mask when outside.
Furthermore, at this time, the risk of the SARS-CoV-2 virus spreading from animals to people is considered to be low, says the CDC.
Who Is At Higher-Risk For SARS-CoV-2 Infection
Currently, there are limited data and information about the impact of underlying medical conditions and whether they increase the risk for severe illness from COVID-19. 'Based on what we know at this time, older people with the following conditions might be at an increased risk for severe illness from COVID-19.'
The CDC says children who are medically complex, who have serious genetic, neurologic, metabolic disorders, and congenital (since birth) heart disease might be at increased risk for severe illness from COVID-19. And, similar to adults, children with obesity, diabetes, asthma, and chronic lung disease, or immunosuppression might be at increased risk for severe illness from COVID-19.
On June 18, 2020, the director of the U.S. NIH, Dr. Francis S. Collins, wrote a posting that stated: 'the findings (of studies) suggest that people with blood type A face a 50% greater risk of needing oxygen support or a ventilator should they become infected with the novel coronavirus. In contrast, people with blood type O appear to have about a 50% reduced risk of severe COVID-19.
SARS-CoV-2 Antibody Duration
Questions regarding the robustness, functionality, and longevity of the antibody response to the virus remain unanswered. A study published on October 28, 2020, found SARS-CoV-2 antibodies were detectable after 5-months.
The U.S. NIH director Dr. Francis S. Collins’s weekly blog, highlight SARS-CoV-2 antibody detection after 4-months.
A study published by the U.S. CDC in 2007 found 'among patients who had the original severe acute respiratory syndrome (SARS-1), SARS-specific antibodies were maintained for an average of 2-years, and significant reduction of immunoglobulin G–positive percentage and titers occurred in the 3rd year post-infection.
The WHO stated researchers had isolated the virus causing pneumonia in December 2019 and found it to be a strain of β-coronavirus (CoV). The virus showed a high nucleotide sequence homology with two SARS-like bat coronaviruses, bat-SL-CoVZC45 and bat-SL-CoVZXC21 (88% homology), and with SARS-CoV (79.5% homology), while only 50% homology with the Middle East respiratory syndrome coronavirus (MERS) CoV.
During 2020, the numbers of people infected with SARS-CoV-2 cases, and related COVID-19 fatalities have varied from country to country, with multiple studies attempting to clarify the clinical differences. A few example studies are as follows:
During April 2020, a study's findings suggested that the virus is evolving and European, North American, and Asian strains might coexist, each of them characterized by a different mutation pattern. These researchers characterized (8) novel recurrent mutations of SARS-CoV-2, with 2891, 3036, 14408, 23403, and 28881 positions predominantly observed in Europe, whereas those located at positions 17746, 17857, and 18060 are exclusively present in North America.
The WHO published an analysis on June 2, 2020, which found that several variants of the SARS-CoV-2 genome exist and that the D614G clade has become the most common variant since December 2019. The evolutionary analysis indicated structured transmission, with the possibility of multiple introductions into the population.
And a study published on July 22, 2020, classified 28 countries into (3) clusters showing different fatality rates of COVID-19. In correlation analyses, they identified that ORF1ab 4715L and S protein 614G variants, which are in strong linkage disequilibrium, showed significant positive correlations with fatality rates (r = 0.41, P = 0.029 and r = 0.43, P = 0.022, respectively).
A study published on October 28, 2020, supported the WHO's recent finding that 'A spike protein mutation D614G became dominant in SARS-CoV-2 during the COVID-19 pandemic.'
On October 28, 2020, a non-peer-reviewed study reported a variant of the SARS-CoV-2 coronavirus that emerged in early summer 2020 has since spread to multiple European countries. The variant, known as A222V, was first observed in Spain has been at transmission frequencies above 40% since July 2020. Outside of Spain, the frequency of this variant has increased to 40-70% in Switzerland, Ireland, United Kingdom, Norway, Latvia, the Netherlands, and France.
A study published on November 12, 2020, found the D614G variant transmits significantly faster and displayed increased competitive fitness than the wild-type virus in hamsters. These data show that the D614G substitution significantly enhances SARS-CoV-2 infectivity, competitive fitness, and transmission in primary human cells and animal models.
SARS-CoV-2 Immunity Responses
Humoral immune responses to SARS-CoV-2 are mediated by antibodies that are directed to viral surface glycoproteins, mainly the spike glycoprotein and the nucleocapsid protein (figure 3). Such antibodies neutralize viral infection of human cells and tissues expressing angiotensin-converting enzyme 2 (ACE2).
Initial reports on cellular immunity to SARS-CoV-2 have consisted of case reports with small numbers of patients, which have indicated that the proportion of CD38+, HLA-DR+ T cells (both CD4+ and CD8+) increases during the first 7–10 days of COVID-19 symptoms and begins to return to baseline around day 20.
Overall, the current data show that both CD4+ T-cell and CD8+ T-cell responses occur in most patients infected by SARS-CoV-2 within 1–2 weeks after symptom onset and produce mainly Th1 cytokines. The frequency of CD4+ T cells targeted to the spike glycoprotein correlates with neutralizing antibody titers, suggesting that the T-cell response might also vary among individuals with different disease severities.
In theory, antibodies induced by coronavirus infections might have broad coronavirus-recognizing characteristics. To examine this, researchers announced on September 24, 2020, they performed an additional enzyme-linked immunosorbent assay, this time using the complete nucleocapsid protein of SARS-CoV-2, including the more inter-species-conserved N-terminal region to allow detection of broadly recognizing antibodies.
Our serological study is unique because it avoids the sampling bias of previous epidemiologic studies based on symptoms-based testing protocols5. In our study, the months of June, July, August, and September 2020 show the lowest prevalence of infections for all four seasonal coronaviruses (Fig. 1d; Wilcoxon signed-rank test, P = 0.004), confirming the higher prevalence in winter in temperate countries, and SARS-CoV-2 might share this feature in the post-pandemic era.
However, these researchers were not able to identify strain variation, which could play a role in susceptibility to reinfection. HCoV-NL63, HCoV-OC43, and HCoV-HKU1 all show different co-circulating genetic clusters. The situation is even more complicated for HCoV-229E, which shows continuous genetic drift.
SARS-CoV-2 Sunlight and Swimming
The U.S. CDC published updated various considerations as some communities in the USA consider opening public beaches. On July 30, 2020, the CDC stated 'evidence suggests that COVID-19 cannot be spread to humans through most recreational water.'
Previously, on June 12, 2020, the US Department of Homeland Security Science and Technology (S&T) Directorate added a new 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 Coronavirus Origin
The SARS-CoV-2 virus is a betacoronavirus, like MERS-CoV and SARS-CoV, both of which have their origins in bats. The sequences from U.S. patients are similar to those China patients initially posted, suggesting a recent emergence of this virus from an animal reservoir, such as horseshoe bats (Rhinolophus sinicus).
And a recent paper published by Lu Jian of Peking University and colleagues analyzed 103 virus genomes and argued that they fell into one of two distinct types, named S and L, distinguished by two mutations. Because 70% of sequenced SARS-CoV-2 genomes belong to L, the newer type, the authors concluded that the virus has evolved.
And in a study published on July 28, 2020, an international research team of Chinese, European, and U.S. scientists announced they have discovered that the lineage that gave rise to the coronavirus has been circulating in bats for decades and likely includes other viruses, with the ability to infect humans.
SARS-CoV-2 Wastewater Detection
Wastewater surveillance may provide valuable information on the prevalence of coronavirus infections in the community. People infected with SARS-CoV-2 shed the virus in their stool even before they show symptoms of COVID-19.
Analyzing sewage for the virus can predict the community level of infection 4-days to 1-week in advance of clinical diagnoses, and show increasing and decreasing levels of coronavirus infection and transmission stated new research.
Recent studies in Australia, France, the Netherlands, and the USA reported that SARS-CoV-2 RNA was successfully detected in wastewater using different concentration methods, such as ultrafiltration, PEG precipitation, and electronegative membrane adsorption followed by direct RNA extraction.
According to a University of Barcelona study published on June 13, 2020, traces of the SARS-CoV-2 virus were found in Barcelona, Spain wastewater, collected in March 2019.
On August 7, 2020, the WHO stated the detection of non-infective RNA fragments of SARS-CoV-2 in untreated wastewater and/or sludge has been reported in a number of settings, such as Milan, Italy; Murcia, Spain; Brisbane, Australia; the Netherlands; and in Paris, France.
A study published on September 18, 2020, measured SARS-CoV-2 RNA concentrations in primary sewage sludge in New Haven, Connecticut, during the Spring of 2020. SARS-CoV-2 RNA was detected throughout the study. Recently, US states, such as Colorado and Ohio, have taken steps toward implementing coronavirus wastewater surveillance.
SARS-CoV-2 Vaccine Candidates
The SARS-CoV-2 vaccine development efforts include platforms such as nucleic acid, virus-like particle, peptide, viral vector (replicating and non-replicating), recombinant protein, live attenuated virus, an inactivated virus approaches. Detailed vaccine development information can be found on this webpage.
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 detect 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 Oral Infection and Preventions
A non-peer-reviewed study published on October 27, 2020, examined RNA that when compared with other oral tissues, 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.
Matched nasopharyngeal and saliva samples found distinct viral shedding dynamics and viral burden in saliva correlated with COVID-19 symptoms including taste loss. Upon recovery, this cohort exhibited salivary antibodies against SARS-CoV-2 proteins.
According to a study published on September 17, 2020, nasal rinses and mouthwashes, which directly impact the major sites of reception and transmission of human coronaviruses (HCoV), may provide an additional level of protection 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% baby shampoo nasal rinse solution inactivated HCoV greater than 99.9% with a 2‐min contact time, said these researchers. Several over‐the‐counter mouthwash/gargle products including Listerine and Listerine‐like products were highly effective at inactivating infectious virus with greater than 99.9% even with a 30‐second contact time.
And, according to Penn State College of Medicine researchers, some of these products might be useful for reducing the viral load, or amount of virus, in the mouth after infection.
SARS-CoV-2 Coronavirus FAQs
NOTE: The content on this page is sourced from the CDC, WHO, clinicaltrials.gov, and the Precision Vax network of websites. This information was last fact-checked by healthcare providers, such as Dr. Robert Carlson.