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Author: Yan Ling Apollonia Tay, Medical Student, University of Otago, Wellington, New Zealand. DermNet NZ Editor in Chief: Adjunct A/Prof Amanda Oakley, Dermatologist, Hamilton, New Zealand. Copy edited by Gus Mitchell. March 2020. Reviewed by Dr Louise Reiche, Dermatologist, Palmerston North, New Zealand. Updated June 2020 by Medical Editor: Dr Helen Gordon, Auckland, New Zealand.


What is COVID-19?

COVID-19 (coronavirus disease 2019) is an illness caused by the coronavirus designated 'SARS-CoV-2' that may lead to serious respiratory disease and can be fatal . The first human cases were reported in China in December 2019, and the infection rapidly spread throughout the world. The World Health Organisation (WHO) declared on 11 March 2020 that the COVID-19 outbreak was officially a pandemic.

  • SARS-CoV-2 belongs to the same family as SARS-CoV, the coronavirus that caused the outbreak of lethal SARS (severe acute respiratory syndrome) in 2003 [1].
  • Other coronaviruses cause the common cold, pharyngitis, laryngitis, and 'flu-like symptoms.
  • The cell receptor for SARS-CoV-2 is the angiotensin-converting enzyme (ACE)-2 in the respiratory system.

In response to the pandemic, vaccines for COVID-19 have been developed as of November 2020. Some vaccines, such as the Pfizer/BioNTech vaccine, were given emergency approval in the US, EU, and UK in late 2020, with vaccination programs commencing soon after. As of December 2020, New Zealand has made vaccine purchase agreements with Pfizer/BioNTech, Janssen Pharmaceutica, Novavax, and AstraZeneca, with country-wide vaccinations expected in mid-2021.

[see COVID-19 immunisation and immunomodulators/biologic agents]

On June 8th, New Zealand was declared free of COVID-19 but continued to maintain closed borders with cases contained at border quarantines. Despite this, COVID-19 re-appeared in New Zealand in August 2020.

New variants of the virus are emerging, some of which appear to be more easily transmissible. 

See also Dermatology patients and COVID-19.

Who gets COVID-19?

COVID-19 affects people of all ages. Older persons and those with underlying chronic medical conditions have a higher risk of developing severe, life-threatening illness [1]. However, young and otherwise healthy people can also become very sick and may die.

The most common underlying chronic medical conditions that are reported to result in more severe disease include [2]:

  • Diabetes mellitus
  • Cardiovascular disease including hypertension
  • Chronic lung disease
  • Cancer (particularly blood, lung, and metastatic cancers)
  • Chronic kidney disease
  • Obesity
  • Smoking.

Those who are immunocompromised are thought to also be at risk, but this has not yet been demonstrated in clinical studies.

How is COVID-19 spread?

The SARS-CoV-2 virus is found in droplets spread by an infected individual coughing, sneezing, talking, or touching items. The droplets may land on surfaces such as door handles, computer keyboards, and tabletops. The virus remains infectious for several days on smooth surfaces but for shorter periods on paper, wood, or cloth [3].

An uninfected individual may touch an invisible droplet then touch their face, transmitting the virus through the mucous membranes of their mouth, nose, and eyes, resulting in infection.

The incubation period for COVID-19 is generally less than 14 days; for most, the onset is 4–5 days after exposure [2].

Patients are infectious for a couple of days before becoming unwell, when unwell, and for some time after clinical recovery from COVID-19.

Infected people without symptoms are also infectious. Although their rate of spreading the infection is about half of those with symptoms, worldwide this group is thought to contribute to the spread of the SARS-CoV-2 virus tenfold.

In countries with rapid community spread, restrictions on movement and crowds are required to prevent a logarithmic increase in cases.

What are the clinical features of COVID-19?

The severity of COVID-19 is variable. Some people infected with the virus SARS-CoV-2 do not develop any symptoms. Approximately 80% of patients have mild symptoms or are asymptomatic and approximately 20% have shortness of breath that develops around 5–8 days after onset [2]. Those with shortness of breath can rapidly deteriorate, and therefore should be admitted to hospital for assessment and management.

The most common symptoms of COVID-19 are:

  • Fever
  • Dry cough
  • Shortness of breath
  • Loss of smell and taste
  • Fatigue/tiredness.

Less common symptoms include:

  • Body aches and pains
  • Runny or blocked nose
  • Sore throat
  • Abdominal pain
  • Diarrhoea
  • Headache
  • Multisystem inflammatory syndrome in children (MIS-C) (abdominal pain, vomiting, diarrhoea, rash, and conjunctivitis) [4]
  • Neurological symptoms such as confusion and coma
  • And many more.

Cutaneous signs of COVID-19

Skin rashes have been frequently described in patients with COVID-19 with approximately 20% reporting skin rashes to be the only clinical sign of COVID-19 [16]. The most common cutaneous manifestations include [2,5]:

  • Morbilliform rash – described at onset of illness as well as in recovery
  • 'COVID toes' (pernio/chilblain-like lesions) theorised to be due to vascular injury caused by the virus
  • Livedo reticularis, (mottled lace-like eruption)/retiform purpura (purple coloured mottling with leakage of blood, non-blanching)/necrotic vascular lesions
  • Acute urticaria
  • Vesicular (chickenpox-like) blisters
  • Multisystem inflammatory syndrome in children (MIS-C) where a polymorphic erythematous eruption is associated with swelling and redness of the hands and feet as well as oral mucositis and conjunctivitis.
  • Telogen effluvium (hair loss) during the recovery phase
    • Usually 2-3 months after COVID infection
    • Recovery expected to occur over 4-6 months and hair density will return to normal
  • Red half-moon sign in nails [13,14].

Other cutaneous manifestations have also been reported in association with COVID-19.

[for more images see

Oral mucosal signs of COVID-19

What are the complications of COVID-19?

The complications of COVID-19 include hypoxia due to viral pneumonia, and in those requiring intensive care, hypoxic respiratory failure most often due to ARDS (Acute Respiratory Distress Syndrome). Other complications include [2]:

  • Acute kidney injury, which may require dialysis
  • Elevated liver enzymes
  • Cardiac complications including heart failure, pericarditis, pericardial effusion, arrhythmia, and sudden death
  • Venous thromboembolism
  • Delirium/encephalopathy.

How is COVID-19 diagnosed?

COVID-19 is diagnosed using nasopharyngeal (respiratory) swabs. These real-time reverse-transcriptase polymerase chain reaction (rRT-PCR) tests detect the SARS-CoV-2 virus. Tests for other respiratory infections such as influenza and respiratory syncytial virus (RSV) may be done at the same time. Saliva tests have also been developed for rapid screening and where nasopharyngeal swabs are not regarded as appropriate.

  • A positive result means the patient has active COVID-19 (or one of the other infections tested).
  • A negative swab is not reliable — the patient may still have COVID-19 (false-negative)
  • The test may be repeated if symptoms progress or for public health purposes.
  • The test may not be offered to everyone requesting it.

Antibody blood tests indicate whether someone has previously been exposed to SARS-CoV-2 and have mounted an immune response. They can be used to determine if weak positive PCR swabs are due to old infection.

The diagnosis of COVID-19 may also be made clinically where the patient has been in contact with a COVID-19 patient, where community infection is widespread, or the patient has recently travelled from a country with community infection.

Blood tests that have been associated with increased disease severity include [2]:

  • Increased D-dimer
  • Increased C-reactive protein (CRP)
  • Increased lactate dehydrogenase (LDH)
  • Increased troponin
  • Increased ferritin
  • Increased creatine kinase (CK)
  • Reduced lymphocyte count
  • Acute kidney injury.

Breathless patients should have their oxygen saturations checked and monitored. Levels of oxygen saturation < 94% on air is considered a marker of severity [2].

As SARS-CoV-2 is excreted in the faeces of infected people, testing of sewage plants has become routine in some countries with low rates of infection. It can warn health authorities the virus is in the local community and nasopharyngeal testing should be increased.

What is the treatment for COVID-19?

The treatment of COVID-19 varies depending on severity. Those with mild disease are best to remain at home to reduce the risk of transmission in the healthcare setting.

Hospital care is required typically due to shortness of breath from viral pneumonia or in severe cases ARDS. Treatment for ARDS may include delivery of low-flow oxygen. If a patient has a higher oxygen requirement this may be delivered via high-flow nasal cannula (HFNC), non-invasive ventilation (NIV), or intubation with mechanical ventilation.

Venous thromboembolism prophylaxis (VTE) should be given to all hospitalised patients unless contraindicated. Patients requiring oxygen or mechanical ventilation should be offered low dose dexamethasone, with reported improved outcomes [6].

Other treatments include remdesivir (an anti-viral medication), and convalescent plasma (a blood product containing antibodies from those who have recovered from the disease) [2].

How can COVID-19 be prevented?

COVID-19 can be prevented — this is why many countries have enforced a ‘lockdown’ and have required people stay at home.

The following personal health practices are strongly encouraged to reduce the risk of infection.

Physical distancing

Keeping a minimum distance between yourself and others to prevent physical contact and possible contamination is an essential step in preventing the spread of the virus.

  • Stay at home; do not go out unless absolutely necessary. Visiting a doctor, supermarket or pharmacy, or physical exercise limited to your neighbourhood is usually permitted; follow your local guidelines.
  • Avoid being closer than 2 metres from others [7].
  • Greet people by waving instead of shaking hands.
  • Keep in touch with family and friends remotely by phone or via the Internet.
  • Frequent handwashing

Handwashing is the most effective way to prevent infection.

  • Wash your hands frequently with soap and water [7].
  • Alternatively, use a hand sanitiser with an alcohol content of at least 60%.
  • Scrub the backs of both hands, between the fingers, and under the nails for at least 20 seconds. If you have sensitive skin, rinse off thoroughly.
  • Dry your hands with a clean cloth or dry paper towels.
  • Moisturisers do not kill SARS-CoV-2 virus so you will still need to wash with soap and water or a moisturising sanitiser if you have previously been given a moisturiser as a soap substitute.
  • Use an oil-based moisturiser such as petroleum jelly to moisturise the hands, preferably about 30 minutes after washing. This will protect the skin from hand dermatitis due to over-washing (see compulsive hand washing). Moisturising your hands will not affect the cleansing properties of handwashing.
  • Do not touch your eyes, nose, or mouth unless your hands are clean.

Good hygiene etiquette

Practice these hygiene measures to prevent the spread of the virus through droplets or physical contact.

  • Cough and sneeze into your inner upper arm to prevent your hands from becoming dirty and spreading an infection to other people or surfaces [3].
  • Face masks, when correctly worn, minimise the risk of you passing the virus on to others especially when asymptomatic.
  • If tissues are used, throw them away immediately and wash your hands properly.
  • Wipe down surfaces using bleach or antiseptic product.
  • Don’t share food and drink, toothbrushes, clothing, bedding, or towels.
  • If involved in healthcare for patients with COVID-19, wear properly applied personal protective equipment after a thorough training in its use.


Many countries require incoming travellers to enter supervised quarantine for 14 days, together with nasopharyngeal swabs on arrival and before release into the community. Close contacts of infected people are asked to self-quarantine and undergo testing.

What is the outcome for COVID-19?

The outcome for COVID-19 depends on the severity of the illness. Up to 20% of cases require hospital admission. Approximately 5–8% of all cases require care in an intensive care unit (ICU) [2]. The reported mortality rate for ICU admissions varies greatly but is around 50% [2].

Mortality from COVID-19 is greatest in older people, especially those over 70 years. Mortality is higher in those with comorbidities associated with severe disease. For example, one-in-four cardiac transplantation patients infected with COVID-19 died from the infection [12]. The overall mortality is thought to be around 2–3% [2].

Typically, those with mild symptoms will recover within 2 weeks, however, severe cases can take three to six weeks or sometimes longer [1,2]. Some are describing variable and often debilitating symptoms for months after contracting the infection and this is under active investigation.

For statistics including current global case numbers and vaccination rates, see the WHO Coronavirus Disease (COVID-19) Dashboard and the WHO's situation reports. For New Zealand's COVID-19 case numbers, see the Ministry of Health's current cases

For more information

In New Zealand, refer to:

  • The Government website,
  • Wang C, Rademaker M, Baker C, Foley P. COVID-19 and the use of immunomodulatory and biologic agents for severe cutaneous disease: An Australia/New Zealand consensus statement. Australas J Dermatol. 2020 Apr 7. doi: 10.1111/ajd.13313. Epub ahead of print. PMID: 32255510.



  1. World Health Organisation. Q&A on coronaviruses (COVID-19). March 2020. Available at: (accessed 23 March 2020).
  2. Free access for COVID-19 articles —
  3. Chin A, Chu JTS, Perera MRA, Hui KPY, et al. Stability of SARS-CoV-2 in different environmental conditions. The Lancet Microbe 2020. doi: Available at:
  4. Multisystem Inflammatory Syndrome in Children (MIS-C) Associated with Coronavirus Disease 2019 (COVID-19). CDC Health Alert. Accessed 16 May 2020. Available at:
  5. Recalcati S. Cutaneous manifestations in COVID‐19: a first perspective. March 2020. J Eur Acad Dermatol Venereol. Accepted Author Manuscript. doi: 10.1111/jdv.16387. Available from:
  6. UK Government press release. World first coronavirus treatment approved for NHS use by government. Available from: (accessed 16 June 2020).
  7. New Zealand Government. Physical distancing. Unite against COVID-19. March 2020. Available at: (accessed 23 March 2020)
  8. American Academy of Dermatology. American Academy of Dermatology shares hand washing tips amid COVID-19. March 2020. Available at: (accessed 23 March 2020)
  9. Centers for Disease Control and Prevention. Coughing & Sneezing. Water, Sanitation & Environmentally-related Hygiene. July 2016. Available at: (accessed 23 March 2020)
  10. American Academy of Dermatology. Guidance on the use of biologic agents during COVID-19 outbreak. March 2020. Available at: (accessed 23 March 2020)
  11. Rademaker M, Baker C, Foley P, Sullivan J, Wang C. Advice regarding COVID-19 and use of immunomodulators, in patients with severe dermatological diseases. Australas J Dermatol. 2020. Accepted Author Manuscript. doi:10.1111/ajd.13295. Available at: (accessed 29 March 2020)
  12. Latif F, Farr MA, Clerkin KJ, et al. Characteristics and Outcomes of Recipients of Heart Transplant With Coronavirus Disease 2019. JAMA Cardiol. Published online 13 May 2020. doi: 10.1001/jamacardio.2020.2159. Journal
  13. Neri I, Guglielmo A, Virdi A, Gaspari V, Starace M, Piraccini BM. The red half-moon nail sign: a novel manifestation of coronavirus infection [published online ahead of print, 2020 Jun 13]. J Eur Acad Dermatol Venereol. 2020;10.1111/jdv.16747. doi:10.1111/jdv.16747. PubMed
  14. Méndez-Flores S, Zaladonis A, Valdes-Rodriguez R. COVID-19 and nail manifestation: be on the lookout for the red half-moon nail sign [published online ahead of print, 2020 Aug 29]. Int J Dermatol. 2020;10.1111/ijd.15167. doi:10.1111/ijd.15167. PubMed
  15. Magro C, Mulvey JJ, Berlin D, et al. Complement associated microvascular injury and thrombosis in the pathogenesis of severe COVID-19 infection: a report of five cases. Transl Res. 2020;220:1–13. doi:10.1016/j.trsl.2020.04.007. PubMed
  16. Visconti A, Bataille V, Rossi N, et al. Diagnostic value of cutaneous manifestation of SARS-CoV-2 infection. Br J Dermatol. 2021;10.1111/bjd.19807. doi:10.1111/bjd.19807. Journal
  17. Nuño González A, Magaletskyy K, Martín Carrillo P, et al. Are oral mucosal changes a sign of COVID-19? A cross-sectional study at a field hospital. Actas Dermosifiliogr. 2021;112(7):640–4. doi:10.1016/j.adengl.2021.05.010. Journal 

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