[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/) › Other human coronaviruses

# Other human coronaviruses

- Virus
- Enveloped

## Contact?

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

## Airborne?

N95 respirator and a negative-pressure room.

- Exam priority: medium

Seven coronaviruses infect people. Four cause common colds; SARS-CoV-1 and MERS-CoV, both from animals, cause severe pneumonia and hospital outbreaks.

Updated Nov 13, 2026

Also called: HCoV-229E, HCoV-NL63, HCoV-OC43, HCoV-HKU1, SARS-CoV-1, MERS-CoV

## Quick facts

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

**Gram / shape**
Spherical with club-shaped spikes

**Spread**
Seasonal HCoVs · SARS-CoV-1 · MERS-CoV

**Causes**
Common cold · Croup in young children

On this page

- The basics Key points
- At a glance
- Morphology
- Transmission
- In Colombia
- Memory aid
- What the colours mean

- Clinical Virulence factors
- Diseases it causes
- Clinical picture
- Diagnosis

- Treatment Treatment
- Prevention

- Study Test yourself

- Connections Connections

## Key points

- Seven human coronaviruses: four seasonal (229E, NL63, OC43, HKU1), SARS-CoV-1, MERS-CoV and SARS-CoV-2
- Enveloped positive-sense RNA virus with the largest RNA genome
- MERS: dromedary camels, Arabian Peninsula, hospital outbreaks, high fatality
- SARS-CoV-1: bats to civets to humans, 2002 to 2004; no cases since 2004
- Seasonal HCoVs: common colds; NL63 can cause croup

## At a glance

**Shape**
Spherical with club-shaped spikes that look like a crown

**Genome**
Single-stranded, positive-sense RNA (about 30 kb, the largest RNA virus genomes)

**Envelope**
Enveloped

**Family**
Coronaviridae: alphacoronaviruses (229E, NL63) and betacoronaviruses (OC43, HKU1, SARS-CoV-1, MERS-CoV, SARS-CoV-2)

**Size**
About 80 to 160 nm

## Morphology

- Spike (S) protein binds the receptor: ACE2 for SARS-CoV-1 and NL63, DPP4 for MERS-CoV, aminopeptidase N for 229E
- OC43 and HKU1 also carry a haemagglutinin-esterase
- Helical nucleocapsid inside the envelope

## Transmission

- Seasonal HCoVs: respiratory droplets, close contact and contaminated hands; winter peaks in temperate countries
- SARS-CoV-1 (2002 to 2004): bats as the source, masked palm civets in markets as the intermediate host, then person to person
- MERS-CoV: dromedary camels (contact, raw milk, urine, undercooked meat); limited person-to-person spread, mainly in households and hospitals
- Large hospital clusters followed aerosol-generating procedures and gaps in infection control
- Precautions: standard for seasonal colds; for suspected MERS or SARS, contact plus airborne precautions with eye protection

**Reservoir:** Bats (ancestral source of SARS-like and MERS-like viruses); Dromedary camels (MERS-CoV); Humans (seasonal HCoVs)

### 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

- Seasonal HCoVs infect the upper airway epithelium and cause mild disease
- SARS-CoV-1 and MERS-CoV reach the lower airway and alveoli, causing diffuse alveolar damage and ARDS
- MERS-CoV also infects kidney cells, and acute kidney injury is common in severe cases
- Older age, diabetes, chronic heart, lung or kidney disease and immunosuppression raise the risk of death

## Diseases it causes

- Common cold (seasonal HCoVs: a frequent cause after rhinovirus) [Common cold (acute viral rhinopharyngitis) →](https://durgical.com/en/conditions/common-cold/)
- Croup in young children (especially NL63) [Croup (laryngotracheobronchitis) →](https://durgical.com/en/conditions/croup/)
- Bronchiolitis and pneumonia in infants, older adults and the immunocompromised [Bronchiolitis (RSV) →](https://durgical.com/en/conditions/bronchiolitis/)
- Severe acute respiratory syndrome (SARS, 2002 to 2004) and Middle East respiratory syndrome (MERS) [Community-acquired pneumonia →](https://durgical.com/en/conditions/community-acquired-pneumonia/)

## Clinical picture

- Seasonal HCoV: rhinorrhoea, sore throat, cough, low fever, lasting a few days
- SARS: high fever and myalgia, a dry cough after 2 to 7 days, then pneumonia in most patients; diarrhoea in some
- MERS: fever, cough and dyspnoea about 5 days after exposure (range 2 to 14), often pneumonia; about a third of reported cases died

## Diagnosis

- Multiplex respiratory PCR panels detect the four seasonal HCoVs
- MERS: RT-PCR on lower respiratory samples (sputum, tracheal aspirate) is preferred, in anyone with pneumonia after travel to the Arabian Peninsula or camel contact
- Chest imaging shows bilateral infiltrates in SARS and MERS pneumonia
- Serology is used for surveillance and contact studies

## Treatment

There is no specific antiviral recommended for seasonal HCoVs, SARS or MERS: care is supportive (oxygen, ventilation, organ support). Antibiotics are only for proven or suspected bacterial co-infection.

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

## Prevention

- Hand hygiene and respiratory etiquette for seasonal colds
- Wash hands before and after contact with camels; avoid raw camel milk, urine and undercooked meat
- Early isolation, PPE and airborne precautions for suspected MERS in health-care settings
- No vaccine is licensed for MERS, SARS or the seasonal coronaviruses

## In Colombia

In Colombia, MERS matters mainly in travellers and pilgrims returning from the Arabian Peninsula. Seasonal coronaviruses circulate all year and appear on respiratory PCR panels in acute respiratory infection surveillance.

## Memory aid

"Four for the cold, three for the crown of severity": four seasonal viruses cause colds; SARS-CoV-1, MERS-CoV and SARS-CoV-2 cause severe disease.

## Test yourself

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

## What is the animal reservoir that infects people with MERS-CoV?

Dromedary camels, through direct contact or raw camel products.

## Which human coronavirus is classically linked to croup?

HCoV-NL63, an alphacoronavirus.

## Which receptor does MERS-CoV use, unlike SARS-CoV-1?

Dipeptidyl peptidase 4 (DPP4); SARS-CoV-1 uses ACE2.

[Add to my cards (3)](https://durgical.app/estudiar/?add=/en/microbiology/other-human-coronaviruses/)

## 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.

## Connections

## Related 4

- [SARS-CoV-2](https://durgical.com/en/microbiology/sars-cov-2/)
- [Rhinovirus](https://durgical.com/en/microbiology/rhinovirus/)
- [Influenza virus](https://durgical.com/en/microbiology/influenza-virus/)
- [Parainfluenza virus](https://durgical.com/en/microbiology/parainfluenza-virus/)

## Related conditions 4

- [Common cold (acute viral rhinopharyngitis)](https://durgical.com/en/conditions/common-cold/)
- [Croup (laryngotracheobronchitis)](https://durgical.com/en/conditions/croup/)
- [Bronchiolitis (RSV)](https://durgical.com/en/conditions/bronchiolitis/)
- [Community-acquired pneumonia](https://durgical.com/en/conditions/community-acquired-pneumonia/)

[← 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: [Human Coronavirus Types](https://www.cdc.gov/human-coronaviruses/php/types/index.html) (CDC, 2024); [Middle East respiratory syndrome coronavirus (MERS-CoV)](https://www.who.int/news-room/fact-sheets/detail/middle-east-respiratory-syndrome-coronavirus-(mers-cov)) (World Health Organization (WHO), 2025); [About Middle East Respiratory Syndrome (MERS)](https://www.cdc.gov/mers/about/index.html) (CDC, 2024); [SARS Basics Factsheet](https://archive.cdc.gov/www_cdc_gov/sars/about/fs-sars.html) (CDC (archived), 2017).

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Representative model, for educational purposes only.

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License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/microbiology/other-human-coronaviruses/