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 a deadly outbreak in 2002-2003. However, it is not the same virus.
SARS-CoV-2 infections cause respiratory disease in humans. On February 11, 2020, the World Health Organization (WHO) announced the official name for this disease, Coronavir Disease 2019 (COVID-19).
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 initially posted, suggesting a recent emergence of this virus from an animal reservoir.
On March 17, 2020, Scripps Research Institute published an analysis of public genome sequence data from SARS-CoV-2 and related viruses found no evidence that the virus was made in a laboratory or otherwise engineered. The genomic features described may help explain in part the infectiousness and transmissibility of SARS-CoV-2 in humans. Although the evidence shows that SARS-CoV-2 is not a purposefully manipulated virus, it is currently impossible to prove or disprove the other theories of its origin.
Based on what is currently known about this coronavirus, the CDC said on March 6, 2020, the transmission, in general, occurs much more commonly through respiratory droplets than through fomites. The spread from person-to-person happens most frequently among close contacts within about 6 feet.
The SARS-CoV-2 infectious rate is estimated the R-0 as between 1.4 to 2.5, which contrasts with the seasonal influenza is a little over 1 RO.
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.
Furthermore, a study published in NEJM on March 17, 2020, found SARS-CoV-2 remained viable in aerosols throughout the duration of the experiment (3 hours), with a reduction in infectious titer from 103.5 to 102.7 TCID50 per liter of air. And, SARS-CoV-2 was more stable on plastic and stainless steel, than on copper and cardboard.
And the coronavirus was detected up to 72 hours after application to these surfaces, although the virus titer was greatly reduced after 48 hours on stainless steel.
According to the CDC on March 3, 2020, scientists reported that the rate of symptomatic infection among a patient’s household members was 10.5%. And, the rate among other close contacts was found to be far less, at 0.45%.
Like all viruses, SARS-CoV-2 evolves over time through random mutations, only some of which are caught and corrected by the virus’s error correction machinery. Over the length of its 30,000-base-pair genome, SARS-CoV-2 accumulates an average of about one to two mutations per month.
A recent paper published by Lu Jian of Peking University and colleagues on March 3, 2020, 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.
An article published in Science on March 9, 2020, said 'Although China accounts for 80% of all COVID-19 cases, only one-third of the published genomes are from China.
As the outbreak unfolds, we expect to see more and more diversity and more clearly distinct lineages.' Using these little changes, researchers can make connections between different cases of COVID-19 and gauge whether there might be an undetected spread of the virus.
Who Is At Higher-Risk
Early information out of China, South Korea, and Italy, shows that some people are at higher risk of getting very sick from this illness. This includes older adults and people who have serious chronic medical conditions like Heart disease, Diabetes, Lung disease.
Preparing For Community-Spread of SARS-CoV-2
Everyone should be prepared for the possibility of a SARS-CoV-2 outbreak in their community, said the CDC on March 7, 2020. Each community can take measures to reduce the spread of this new coronavirus. Individuals can practice everyday prevention measures like frequent hand washing, staying home when sick, and covering coughs and sneezes.
Community-based interventions such as school dismissals, event cancellations, social distancing, and creating employee plans to work remotely can help slow the spread of SARS-CoV-2. Decisions about the implementation of community measures will be made by local and state officials, in consultation with federal officials as appropriate, and based on the scope of the outbreak and the severity of illness.
SARS-CoV-2 preventive vaccines are currently being developed, but have not been approved for use by the US Food and Drug Administration.
SARS-CoV-2 Differences From SARS-CoV
A study published on March 3, 2020, found that the SARS-CoV-2 spike was 10 to 20 times more likely to bind ACE2 on human cells than the spike from the SARS virus from 2002. This may enable SARS-CoV-2 to spread more easily from person to person than the earlier virus.
Despite similarities in sequence and structure between the spikes of the two viruses, three different antibodies against the 2002 SARS virus could not successfully bind to the SARS-CoV-2 spike protein.
On March 16, 2020, researchers at the Institute of Human Virology at the University of Maryland School of Medicine and the Global Virus Network predict that SARS-CoV-2, and COVID-19, the disease it causes, will follow a seasonal pattern similar to other respiratory viruses, such as the seasonal flu.
A previous study published by The Lancet in 2004, discussed 'Seasonality of infectious diseases and SARS–what we don't know can hurt us.'
- Our understanding of the forces driving seasonal disappearance and recurrence of infectious diseases remains fragmentary, thus limiting any predictions about whether, or when, SARS will recur.
- Most established coronaviruses exhibit winter seasonality, with a unique ability to establish persistent infections in a minority of infected animals.
- It is true that most established respiratory pathogens of human beings recur in wintertime, but a new appreciation for the high burden of disease in tropical areas reinforces questions about explanations resting solely on cold air or low humidity.
- Newly emergent zoonotic diseases such as Ebola or pandemic strains of influenza have recurred in unpredictable patterns.
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, on March 22, 2020.