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last updated 28 Oct 2022
First described in detail in the 1960s, the coronavirus gets its name from a distinctive corona or 'crown' of sugary-proteins that projects from the envelope surrounding the particle.
SARS-CoV-2 is a type of single stranded enveloped positive-sense RNA (Ribonucleic acid) (ssRNA(+) retrovirus like SARS, MERS and HIV -- One of 7 classes of viruses. See Group IV: Single-stranded RNA viruses - Posite sense below

RNA is usually generated from DNA as part of cell replication. Retroviruses are "retro" because they reverse the direction of the normal gene copying process. The virus genes are copied into the DNA where it replicates thru the normal cell replication process which ends up making viral proteins. Viruses require a living host to replicate as opposed to bacteria which are larger single-celled microorganisms that can survive on their own.
It causes potentially deadly diseases in mammals and birds.
Symptoms vary.

An Pandemic of SARS (Severe acute respiratory syndrome), a type of coronavirus, affected 26 countries and resulted in more than 8000 cases in people from November 2002 to July2003, when the global outbreak was declared over.
Google "How was SARS eradicated?""

The SARS-CoV-2 virus is responsible for the COVID-19 disease.
(Just like HIV is responsible for AIDS)

In late 2017, Chinese scientists traced SARS to cave-dwelling horseshoe bats in Wuhan province.
As of February 2020 the search for the animal origin of COVID-19 is ongoing.

MERS (Middle East Respiratory Syndrome), another kind of coronavirus was first identified in Saudi Arabia in 2012 in people displaying symptoms of fever, cough, shortness of breath and occasionally gastrointestinal problems such as diarrhoea.

COVID-19 origin:
On 30 December 2019 bronchoalveolar lavage samples were collected from a patient with pneumonia of unknown etiology in Wuhan province, China . It analyzed positive for pan-Betacoronavirus, one of 4 genuses of corona virus which includes SARS .

First called NCP - Novel Coronavirus Pneumonia, On February 11th 2020 the WHO (World Health Organization) announced that "COVID-19" will now be the official name of the disease caused by the new coronavirus from China.
"CO" stands for "corona", "VI" for "virus" and "D" for "disease",.
The agency had earlier given the virus the temporary name of "2019-nCoV acute respiratory disease".

Coronavirus Symptoms Examples - Worldometer
See Terms below.
Source: Management of Patients with Confirmed 2019-nCoV | CDC April 3, 2020 version
Timeline per John Hopkins
 0  Exposure
    Incubation - (exposure to symptoms) 
        2-14 days for alpha and Delta
         3 days for Omicron
    Median 5 days. 97.5% will show symptoms by 11.5 days.
    Contagious 2-3 Days before Symptoms
    Infectious 1-2 days before symptoms
 2-14  Symptoms - Fever, fatigue, muscle pain, dry cough
 6-12  Difficulty breathing
11-16  Hospital for those with still breathing troubles
12  Acute respiratory distress
14 ICU for critical respiratory issues
16 Fever ends
17 Shortness of breath ends
22 Death for those worst affected
26 Recovered
Source: COVID-19 incubation timeline: When am I contagious? | Providence"
See also Management of Patients with Confirmed 2019-nCoV | CDC Nov. 3
Flu vs Coronavirus:
  • Covid-19 vs the Flu

    Humidity - Temperature:
    There is a school of thought that says,
    "Infections may subside in the summer because of higher temperatures and humidity."
    Medical people note that flu declines in the summer this may be the reason.
    There is some data to support this for coronavirus, but it is inconclusive.
    Several theories exist: Literature Review of the Effect of Temperature and Humidity on Viruses | NIH, 2011
    Vulnerability or Risk Factors for serious complications or death.
    Case Fatality Rate (CFR): Over 80 years old (CFR 14.8%) cardiovascular disease (CFR 13.2%), diabetes (9.2%), chronic respiratory disease (8.0%), hypertension (8.4%), and cancer (7.6%).
    See Case Fatality Rate (CFR)
    Group IV & V: Single-stranded RNA viruses:
    The ssRNA viruses belong to Class IV or V of the Baltimore classification. They could be grouped into positive sense or negative sense according to the sense of polarity of RNA. The single stranded RNA is the common feature of these viruses. The replication of viruses happens in the cytoplasm or nucleus (for segmented class V viruses). Class IV and V ssRNA viruses do not depend as heavily as DNA viruses on the cell cycle.[clarification needed]

    Group IV: Single-stranded RNA viruses - Positive-sense Main article: positive-sense ssRNA virus The positive-sense RNA viruses and indeed all RNA defined as positive-sense can be directly accessed by the host ribosomes immediately to form proteins. These can be divided into two groups, both of which reproduce in the cytoplasm:

    Viruses with polycistronic mRNA where the genome RNA forms the mRNA and is translated into a polyprotein product that is subsequently cleaved to form the mature proteins. This means that the gene can utilize a few methods in which to produce proteins from the same strand of RNA, all in the sake of reducing the size of its gene.
    Viruses with complex transcription, for which subgenomic mRNAs, ribosomal frameshifting, and proteolytic processing of polyproteins may be used. All of which are different mechanisms with which to produce proteins from the same strand of RNA.
    Examples of this class include the families Astroviridae, Caliciviridae, Coronaviridae, Flaviviridae, Picornaviridae, Arteriviridae, and Togaviridae.
    Source: Baltimore classification - Wikipedia


    Marc Johnson Twitter Sept. 2022

    Old Data June 2020 Variants of concern
    Name Lineage Status
    Alpha B.1.1.7 Emerged in Britain in December and thought to be roughly 50 percent more infectious. Now dominant in the U.S.
    Beta B.1.351 Emerged in South Africa in December. Reduces the effectiveness of some vaccines.
    Gamma P.1 Emerged in Brazil in late 2020. Has mutations similar to B.1.351.
    Delta B.1.617.2 Prevalent in India. Carries the L452R spike mutation, among others.
    Variants of interest (Less dangerous)
    Name Lineage Status
    Epsilon B.1.427, B.1.429 Common in California and thought to be about 20 percent more infectious. Carries the L452R mutation.
    Zeta P.2 First documented in Brazil.
    Eta B.1.525 Spreading in New York. Carries some of the same mutations as B.1.1.7.
    Theta P.3 First documented in the Philippines.
    Iota B.1.526 Spreading in New York. One version carries the E484K mutation, another carries S477N.
    Kappa B.1.617.1 Prevalent in India. Carries the L452R spike mutation, among others.
    See Coronavirus Variants: Latest News and Updates - The New York Times for others.

    Source: Eric Topol (@EricTopol) The COVID-19 Delta Variant: |

    Delta Variant:
    On June 14 the CDC declared the delta variant a "variant of concern," a designation given when there is increased evidence of factors such as transmissibility or severity or reduced effectiveness of vaccines or treatments.
    As of June 5th it accounted for 10% of the cases in the US.
    It will most likely become the dominant strain in the US in 1-2 months.

    It is 40%-60% more infectious or transmissable- i.e. spreads easier.
    It may be more serious - Causes more severe illness, but more data is needed.
    It's more important to get 2 doses of the vaccine.
    The first dose which was 49% effective for Pfizer and Moderna with the original viruus is only 30-35% effective with the delta variant.
    The Pfizer vaccine is 94% effective with the Alpha variant after the second dose and 88% effective with the Delta variant.
    The Moderna vaccine is 75% effective with the Alpha variant after the second dose and 67% effective with the Delta variant.
    See NEJM article in vaccines.

    Terms - Glossary:
    The virus: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2, 2019-nCoV)

    The disease: Novel coronavirus (Covid-19)

    Quarantine - Exposure but no symptoms

    Isolation - Positive diagnosis

    Epidemic - A quick rise in the number of cases of a disease beyond what is normally expected in a geographical area.

    Pandemic - A disease that has spread across many countries and affects a large number of people.

    Endemic - An infection which is constantly maintained at a baseline level in a geographic area without external inputs. For example, chickenpox is endemic (steady state) in the UK, but malaria is not.
    Andy slavitt author of Preventable defines it as a predictable state where there is drift (minor changes) not shifts (completely different mutations and characteristics.)

    Asymptomatic - Infected people who never show symptoms.

    dyspnea - Difficult or labored breathing.

    Fomites - objects or materials which are likely to carry infection, such as clothes, utensils, and furniture.

    Hypoxia - A condition in which the body or a region of the body is deprived of adequate oxygen supply at the tissue level. It can show up as a change in skin color. It can damage organs.

    IDR Infection Detection Ratio

    IHR infection–hospitalisation ratios

    IFRs infection–fatality ratios

    Latency - Clinical Latency - Basically the same as incubation as far as I know. Viral Latency - Virus becomes inactive but still exists.

    Pre-Symptomatic - Infected people with no symptoms who will develop them later.

    CLI - COVID-Like Illness

    ILI - Influenza-like illness

    NCIRD - National Center for Immunization and Respiratory Diseases

    NSSP - National Syndromic Surveillance Program

    PIC - pulmonary intravascular coagulopathy.

    Coagulopathy (also called a bleeding disorder) is a condition in which the blood's ability to coagulate (form clots) is impaired.

    ACE 2 - Angiotensin-converting enzyme 2 (ACE2

    More Links:
    High Humidity Leads to Loss of Infectious Influenza Virus from Simulated Coughs | PLos ONE
    Literature Review of the Effect of Temperature and Humidity on Viruses
    These are 6 of the main differences between flu and coronavirus - MIT Technology Review
    We Are 100 Times Safer Now Than In Early March: Here is the Math
    General virology – Knowledge for medical students and physicians
    Are RNA Viruses Candidate Agents for the Next Global Pandemic? A Review | ILAR (Institute for Laboratory Animal Research) Journal | Oxford Academic 2017