COVID-19 (SARS-CoV-2 Coronavirus)

Author: Rebecca Ting

Editors: Nicole Nwosu, Dina Abbas, Helia Mansouri Dana

 

Overview

The novel coronavirus  (COVID-19) is part of the large family of coronaviruses, is caused by severe acute respiratory syndrome coronavirus (SARS-CoV-2) and is typically found within animals (BCCDC, 2020).  This virus emerges from their natural host to humans, causing  respiratory-related illness, such as acute respiratory distress syndrome, pneumonia, asthma or lung cancer (BCCDC, 2020). COVID-19 is a novel virus  that was first discovered in December 2019 in Wuhan, Hubei, China (Wu et. al., 2020). 

COVID-19 causes mild to severe respiratory problems and can even result in death (BCCDC, 2020). Recent data has shown that the mortality rates of the virus are 2-3% (Wu et. al., 2020). In January 2020, the outbreak spread to various countries and by February 6th, 28,276 cases and 565 deaths worldwide were recorded by the World Health Organization (WHO) (Wu et. al., 2020).  The World Health Organization declared COVID-19 outbreak as a global pandemic on March 11th, 2020 (Majumder et. al., 2021; BCCDC, 2020; Gao et. al., 2021). As of the time of this publication, its spread has resulted in more than 3.8 million deaths worldwide (Aleem et. al., 2021). 

As of August 2021, the four main variants of SARS-CoV-2 include alpha, beta, gamma and delta variants of the virus have been considered globally concerning (Aleem et. al., 2021). Current vaccines have been proven effective for most of the variants, however further studies are being investigated with regards to vaccination in children, as well as the need for additional doses for boosting immunity against the currently circulating delta variant (CDC, 2020)

 

Etiology 

The origin of COVID-19 is not clear though it is believed to be a zoonotic disease (Wu et. al., 2020). Zoonotic diseases originate due to transmission of a virus, bacteria or parasites from an animal to humans (Wang et. al., 2014).  Also, Coronaviruses belong to the Nidovirales family, which include Coronaviridae and Torovirinae subfamilies. Coronavirus belongs to the Coronaviridae subfamily, which is further classified into 4 subtypes including Alpha, Beta, Gamma and Delta coronavirus (Phan et. al., 2018). Research has shown that SARS-CoV-2 could be related  to the beta-coronaviruses which are bat and rodent gene sources (Cascella et. al., 2021). 

SARS-CoV-2 is a positive sense single-stranded RNA with 5’cap and 3’UTR poly (A) tale, the virus contain a spike glycoproteins on its envelope which give the coronaviruses its crown-like appearance and facilitate its penetration to the host cell (Mohamadian et. al., 2021, Majumder et. al., 2021). 

The replication of SARS-CoV-2the COVID-19 is quite similar to the rest of the viruses as it requires a host cell and in general it undergoes the normal replication process starting with attaching its spike glycoproteins to the angiotensin converting enzyme 2 (ACE2) receptor protein at the surface of the host cell membrane that facilitates its invasion, followed by uncoating, replication and finally the release step (Majumder, et. al., 2021)

 

Symptoms

An infected individual could appear to be asymptomatic for up to 14 days after the initial exposure to the virus (Oran et. al., 2020). Infected asymptomatic persons account for 40% to 45% of SARS-CoV2 infections and can transmit the disease for more than 14 days (Oran et. al., 2020). 

The signs and symptoms of COVID-19 vary from individual to individual. Some common symptoms include :

  • Chills
  • Fever 
  • Loss of taste or smell
  • Breathing difficulty

Additional symptoms include: 

  • Loss of appetite 
  • Diarrhea
  • Headache  
  • Muscle/Body aches 
  • Sore throat 
  • Nausea or Vomiting
  • Fatigue 

It is suggested to go to an emergency department if one experiences: chest pain, unable to drink liquids, hard to breathe and feeling sick or confused (CDC, 2020).    

 

Risk factors

Transmission of the virus is likely from person to person and can occur through contact and respiratory droplets (Wu et. al., 2020). Although COVID-19 is associated with causing respiratory illnesses, it can also impact multiple organs (Mokhtari et. al., 2020). This includes the kidneys, lungs, heart, liver, nervous system, gastrointensitinal and hematological parts of the body (Mokhtari et. al., 2020).  Additionally, COVID-19 can induce multi-organ failure in severely infected patients (Mokhtari et. al., 2020). 

SARS-CoV-2 has high transmission rates between humans compared to other forms within the coronavirus family (Padhan et. al., 2021). Due to the virus’ novelty, and lack of natural immunity make the disease more aggressive (Li et. al., 2005; Padhan et. al., 2021). When contracting the virus, there is a delayed period before one’s body develops immune responses (Padhan et. al., 2021). 

The risk of falling severely ill from COVID-19 is higher for older adults and those who face long duration of systemic health and social inequities (Zheng et. al., 2020; CDC, 2020). High risk people also include those with chronic or severe medical conditions. A few of the following conditions include:

  • Chronic kidney, lung, liver disease
  • Diabetes (Type 1 or 2)
  • Heart conditions 
  • Cancer 
  • Immunocompromised individuals
  • Thalassemia 
  • Obesity 

(CDC, 2020)

  

Diagnosis

The  strategies used to reduce COVID-19 spread and to ensure safety include 14-days quarantine for persons who have been potentially exposed to an infected person (either symptomatic or asymptomatic) as recommended by the WHO (CDC, 2020; Hawryluck et. al., 2004; Wells et. al., 2021). Whenever possible, molecular testing for SARS-CoV-2 using RT-PCR is recommended by the WHO. A nasopharyngeal swab is typically used for specimen collection, and the sample will be sent to a lab for analysis (WHO, 2020; Wu et. al., 2020). 

Testing based on nucleic acid amplification techniques requires well resourced laboratories and may not be suitable for under-resourced areas or for timely detection (WHO, 2020). Rapid diagnostic and antigen testing is used in at- or near-point-of-care, though health care providers must be mindful about rapid testing as they may not yield the most accurate results (Brihn et al., 2021). Antigen (Ag) tests and antibody (Ab) tests using patients’ serum are currently used to confirm test results  based on facility  limitations and advantages (WHO, 2020).

 

Treatment

Pharmaceutical Treatment 

Currently, there are no clinically approved therapeutics by the U.S Food and Drug Administration (FDA) for COVID-19 treatment (Majumder et. al.,2021). Hence, the early diagnosis of COVID-19 patients is the best method to control the infection accompanied by the patient’s isolation (Majumder et. al.,2021).

Vaccines

At the time of this publication, vaccine rollout has begun in a few countries, being distributed to health care personnel and residents living in long term care homes before becoming available to citizens (Rasmussen et. al., 2021). Various vaccines were put under consideration including the now widely distributed vaccines like Moderna, Pfizer-BioNTech, Johnson & Johnson and AstraZeneca (Rasmussen et. al., 2021). 

Pfizer-BioNTech and Moderna hold genetic information that makes a protein of SARS-CoV-2, injecting it into muscle cells to be recognized by the individual’s immune system and is later degraded in the body (Rasmussen et. al., 2021). Johnson & Johnson and AstraZeneca manufacture an unreplicatable viral vector to deliver the same protein of SARS-CoV-2 into one’s body to trigger an immune response (Rasmussen et. al., 2021). 

Two doses of the vaccine have been highly recommended and necessary for long term protection (Pilishvili et al., 2021; Tenforde et al., 2021)). Mixing of specific vaccines (i.e., getting Pfizer-BioNTech as one’s first dose and Moderna as one’s second dose) have been approved after showing effectiveness through clinical trials and population studies conducted in different countries such as the UK and Spain (BCCDC, 2020). 

Vaccine side effects vary within different individuals. Some side effects include: 

  • Fever
  • Muscle Aches 
  • Joint Aches 

(CDC, 2020)

 

Preventative Measures 

Prevent of spread of the virus include the following : 

  • Full vaccination (two doses as recommended by the CDC)
  • Wash hands and avoid touching face
  • Practice social distancing. 
    • It is recommended that when you are outside of your home to keep at least two meters (about six feet) distance from another individual. 
  • Wear masks (fitted on the face with no gaps, covering the mouth and the nose) 
  • Regularly clean and disinfect products 

(CDC, 2020)

 

Misdiagnosis articles

Eshaghi, H., Ziaee, V., Khodabande, M., Safavi, M., & Haji Esmaeil Memar, E. (2021). Clinical Misdiagnosis of COVID-19 Infection with Confusing Clinical Course. Case Reports in Infectious Diseases, 2021, e6629966. doi:10.1155/2021/6629966

 

Messerli, F. H. (2019). Ephemeral Coronary Heart Disease: Now you see it, now you don’t: A cardiologist’s personal story. European Heart Journal, 40(24), 1906–1908. doi:10.1093/eurheartj/ehz400

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