[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Microbiology](https://durgical.com/en/microbiology/) › [Respiratory RNA viruses](https://durgical.com/en/microbiology/groups/respiratory-rna-viruses/) › SARS-CoV-2

[Microbiology](https://durgical.com/en/microbiology/) · [Respiratory RNA viruses](https://durgical.com/en/microbiology/groups/respiratory-rna-viruses/)

# SARS-CoV-2

- Virus
- Enveloped
- Contact
- Airborne
- Exam priority: high

The coronavirus behind COVID-19. It spreads through the air, mostly indoors, and can cause anything from a cold to severe pneumonia.

Updated 2026-11-01

Also called: COVID-19 coronavirus, novel coronavirus

## Key points

- Positive-sense betacoronavirus; spike binds ACE2
- Loss of smell and taste as a clinical clue
- Dexamethasone only for patients with hypoxaemia
- Health workers: N95 respirator, eye protection, gown and gloves

## At a glance

**Shape**
Spherical with a crown of spikes

**Genome**
Single-stranded, positive-sense RNA

**Envelope**
Enveloped

**Family**
Coronaviridae, genus Betacoronavirus

**Size**
About 60 to 140 nm

## Morphology

- Enveloped virus with the spike (S) protein, which binds the ACE2 receptor
- One of the largest RNA genomes, with partial proofreading
- Successive variants with spike mutations

## Transmission

- Respiratory particles and aerosols from breathing, talking, coughing or sneezing
- Higher risk with close contact and poorly ventilated indoor spaces
- Contaminated surfaces, of lesser importance
- Spread possible before symptoms or without them

**Reservoir:** Humans; probable origin in bats

### Isolation precautions

What the care team adds to standard precautions.

**Contact**
Gown and gloves; dedicated equipment. For C. difficile, soap-and-water hand washing.

**Airborne**
N95 respirator and a negative-pressure room.

## Virulence factors

- Spike binds ACE2 and the protease TMPRSS2 activates fusion
- Damage to alveolar epithelium and endothelium, with microvascular thrombosis
- Dysregulated inflammatory response in severe disease

## Diseases it causes

- COVID-19, from mild illness to severe pneumonia; post-COVID condition [COVID-19 →](https://durgical.com/en/conditions/covid-19/)
- Acute respiratory distress syndrome in severe COVID-19 [Acute respiratory distress syndrome (ARDS) →](https://durgical.com/en/conditions/acute-respiratory-distress-syndrome/)
- Multisystem inflammatory syndrome in children, weeks after infection

## Clinical picture

- Incubation 3 to 6 days
- Fever, chills, sore throat, cough, fatigue, headache; loss of smell or taste
- Pneumonia with hypoxaemia and acute respiratory distress syndrome
- Post-COVID condition with fatigue, breathlessness and poor concentration
- Higher risk with older age and chronic disease

## Diagnosis

- RT-PCR of a nasopharyngeal swab
- Rapid antigen tests, useful in the first days of symptoms
- X-ray or CT: bilateral, peripheral ground-glass opacities
- Lymphopenia, raised D-dimer and C-reactive protein in severe disease

## Treatment

Antivirals for people at risk with early illness: main protease inhibitors (nirmatrelvir boosted with ritonavir) and nucleotide analogues (remdesivir). In severe disease with hypoxaemia, corticosteroids (dexamethasone) and immunomodulators such as interleukin-6 inhibitors are used.

Drug class only; doses and regimens are set by the clinician from the current guideline.

In Pharmacology:

- [Ritonavir](https://durgical.com/en/pharmacology/ritonavir/)
- [Remdesivir](https://durgical.com/en/pharmacology/remdesivir/)
- [Dexamethasone](https://durgical.com/en/pharmacology/dexamethasone/)

## Prevention

- Vaccination, which reduces severe disease, hospital stays and death
- Ventilation, masks in risky situations and hand hygiene
- In hospital: N95 respirator, eye protection, gown and gloves

**Vaccine:** Several vaccines (mRNA, viral vector, protein subunit and inactivated); Colombia vaccinated at scale from 2021 and now prioritizes the highest-risk groups.

## In Colombia

Colombia went through several COVID-19 waves from 2020; today the INS monitors SARS-CoV-2 within integrated acute respiratory infection surveillance.

## Memory aid

SARS-CoV-2 puts its "key" (the spike) into the ACE2 "lock": blocking the key is the idea behind the vaccine.

## Test yourself

Think of the answer, then tap the question to see it.

## Which cell receptor does the SARS-CoV-2 spike protein bind?

Angiotensin-converting enzyme 2 (ACE2).

## Which COVID-19 patients receive dexamethasone?

Those with severe disease and hypoxaemia or needing oxygen; not mild cases.

## What protective equipment is recommended when caring for a COVID-19 patient?

An N95 or higher respirator, eye protection, gown and gloves, on top of standard precautions.

[Add to my cards (3)](https://durgical.app/estudiar/?add=/en/microbiology/sars-cov-2/)

## Related

- [Influenza virus](https://durgical.com/en/microbiology/influenza-virus/)

## Related conditions

- [COVID-19](https://durgical.com/en/conditions/covid-19/)
- [Acute respiratory distress syndrome (ARDS)](https://durgical.com/en/conditions/acute-respiratory-distress-syndrome/)

## What the colours mean

**Gram-positive**
Thick peptidoglycan wall: stains purple.

**Gram-negative**
Thin wall with an outer membrane: stains pink.

**Acid-fast**
Lipid-rich wall (mycobacteria): Ziehl–Neelsen stain.

**Contact**
Gown and gloves; dedicated equipment. For C. difficile, soap-and-water hand washing.

**Droplet**
Surgical mask within about a metre; single room.

**Airborne**
N95 respirator and a negative-pressure room.

[← Back to the group: Respiratory RNA viruses](https://durgical.com/en/microbiology/groups/respiratory-rna-viruses/)

Educational content on microorganisms; not a treatment guide and no substitute for a health professional's advice. No doses are given.

Sources: [Coronavirus disease (COVID-19)](https://www.who.int/news-room/fact-sheets/detail/coronavirus-disease-(covid-19)) (World Health Organization (WHO), 2025); [Appendix A: Type and Duration of Precautions Recommended for Selected Infections and Conditions](https://www.cdc.gov/infection-control/hcp/isolation-precautions/appendix-a-type-duration.html) (CDC, 2024).

## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake

Representative model, for educational purposes only.

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Source: https://durgical.com/en/microbiology/sars-cov-2/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/microbiology/sars-cov-2/