Coronavirus disease (COVID-19) is an infectious disease caused by the SARS-CoV-2 virus.
Most people infected with the virus will experience mild to moderate respiratory illness and recover without requiring special treatment. However, some will become seriously ill and require medical attention.
Older people and those with underlying medical conditions like cardiovascular disease, diabetes, chronic respiratory disease, or cancer are more likely to develop serious illness.
Anyone can get sick with COVID-19 and become seriously ill or die at any age.1
1. World Health Organization. Coronavirus disease (COVID-19). Overview. 2022
COVID-19 Cause & Transmission
COVID-19 is a disease caused by a new form of coronavirus, first reported in December 2019. Coronaviruses are a large family of viruses that cause respiratory infections. These can range from the common cold to more serious diseases.2
The virus can spread from person to person through:
- close contact with an infectious person (including in the 48 hours before they had symptoms)
- contact with droplets from an infected person’s cough or sneeze
- touching objects or surfaces (like doorknobs or tables) that have droplets from an infected person, and then touching your mouth or face.
Current evidence suggests that the most likely spread is from respiratory droplets between people from close contact with each other. 3,4
People are believed to be most infectious two days before they start showing symptoms. However even if people do not show any symptoms, they can still spread the virus to other people.
2. Australian Government Department of Health and Aged Care. COVID-19 disease and symptoms Last updated 14 October 2022
3. World Health Organization. Coronavirus disease (COVID-19): How is it transmitted? Accessed 19 October 2022
4. Brooks JT, Butler JC. Effectiveness of Mask Wearing to Control Community Spread of SARS-CoV-2. JAMA. 2021;325(10):998–999. doi:10.1001/jama.2021.1505
Symptoms of COVID-19 can range from mild illness to pneumonia. Most people will recover easily, and others may get very sick very quickly. People with coronavirus may experience symptoms such as:
- respiratory symptoms,
- sore throat,
- shortness of breath.
Other symptoms can include runny nose, acute blocked nose (congestion), headache, muscle or joint pains, nausea, diarrhoea, vomiting, loss of sense of smell, altered sense of taste, loss of appetite and fatigue.
Most people will recover from COVID-19 within a few weeks however 1 in 6 may experience complications.
Older people and those with underlying medical conditions e.g., heart disease or diabetes may be more likely to develop a more serious illness.
What causes COVID-19 complications?
COVID-19 complications may be caused by a cytokine storm. Cytokines are inflammatory proteins that can flood the bloodstream after an infection like COVID-19 triggers the immune system. The large influx of cytokines can cause damage to many organs of the body like the heart, lungs, liver and kidneys.
The most common complications are of the lungs and respiratory system, they are:
- Acute Respiratory Failure: a serious condition when the lungs can’t get enough oxygen to the rest of the body and there is a build-up of carbon dioxide causing damage to other organs of the body
- Pneumonia: an infection that affects one or both lungs. This type of pneumonia may cause scar tissue and long-term damage to the lungs
- Acute Respiratory Distress Syndrome: the lungs become so severely damaged that fluid flows into them which inhibits the body getting oxygen into the bloodstream
The other complications may be:
- Acute liver injury
- Acute cardiac injury
- Secondary infection: the body may develop another infection unrelated to COVID-19 e.g., bacterial infections like Strep or Staph are usually the culprits
- Acute kidney injury
- Septic shock
- Disseminated intravascular coagulation: Abnormal clotting can lead to internal bleeding and organ failure
- Blood clots including those causing pulmonary embolism
- Multisystem inflammatory syndrome in children: some organs in the body become severely inflamed. Symptoms include fever, belly pain, vomiting, diarrhoea, headache, rash and confusion
- Chronic fatigue: Symptoms may include brain fog, severe fatigue, pain, trouble thinking or dizziness
- Damage to the brain: Even in young people, COVID-19 can cause strokes and Guillain barre syndrome. COVID-19 may also increase the risk of Parkinson’s disease and Alzheimer’s disease
- Dermatologic: Rash
- Neurologic: Loss of taste, smell and sleep disturbance
- Psychiatric: depression, anxiety, changes in mood
People with severe symptoms may be hospitalised and treated in the Intensive Care Unit with mechanical devices such as ventilators. Surviving these experiences can make them more likely to suffer from post-traumatic stress disorder, depression and anxiety.5,6,7
Who is Most at Risk?
Among patients with vaccine breakthrough COVID-19 hospitalisations 40-44% had immunosuppression.8,9
5. Post-COVID conditions: Information for healthcare providers. Centers for Disease Control and Prevention. https://www.cdc.gov/coronavirus/2019-ncov/hcp/clinical-care/post-covid-conditions.html. Accessed 19 October 2022
6. Post-COVID-19 conditions. Centers for Disease Control and Prevention.
7. COVID-19 (coronavirus): Long-term effects, Mayo Clinic, https://www.mayoclinic.org/diseases-conditions/coronavirus/in-depth/coronavirus-long-term-effects/art-20490351. Accessed 19 October 2022
8. Brosh-Nissimov T et al. Clin Microbiol Infect. 2021;27:1652–1657
9. Tenforde MW et al. Clin Infect Dis. 2021;ciab687
COVID-19 cannot be controlled by one approach alone.
A combination of masks, education, hygiene, social distancing, vaccination and antiviral treatments continue to be recommended10.
Evusheld (tixagevimab and cilgavimab) received provisional approval on 24 February 2022 for the pre-exposure prevention of COVID-19 in adults and adolescents aged 12 years and older. For people who are immunocompromised or who have a history of a severe adverse reaction to the COVID-19 vaccine, Evusheld may be considered.11
Tixagevimab and cilgavimab are monoclonal antibodies that stick to the spike protein on the COVID 19 virus and stop it from getting into the lungs.
Who Should be Vaccinated?
- Vaccination against COVID-19 is recommended for all from 5/6 years of age
- A two-dose schedule using Comirnaty (Pfizer) or Moderna is recommended12
10. Australian Government Department of Health Protect yourself and others from COVID 19 Last updated 14 October 2022
11. Australian Government Department of Health and Ageing Therapeutic Goods Administration (TGA) Guidance and resources. Prescription medicines registrations. Evusheld (Astra Zeneca Pty Ltd) 26 February 2022
12. Australian Department of Health and Ageing Clinical Recommendations for COVID 19 vaccines ATAGI clinical guidance for Covid 19 vaccines Last updated 21 October 2022
COVID-19 Vaccine Efficacy
COVID-19 booster protects against omicron severe disease.13
An Australian-first COVID-19 vaccine effectiveness study has shown that receipt of a booster (third) COVID-19 vaccine dose provided 65% greater protection against hospitalisation/death from Omicron than 2 vaccine doses
The study findings confirm that the COVID-19 vaccine schedule used in Australia protects against severe disease from Omicron SARS-CoV-2 infection. For adults aged 70 years and older, the benefits were especially great with a significant reduction in hospitalisation or death from COVID-19. For every 192 adults aged 70 years and older who received a third dose, at least one hospitalisation or death was prevented. The benefits of a third dose were also significant in adults aged 40–69 years.
Future studies will look at protection gained following a fourth dose.
Children between 5-11 years of age were made eligible for the COVID 19 vaccine in the UK from February 2022. Subsequently, there has been a reduced incidence of Multi-system inflammatory Syndrome in kids with Covid 19. This is possibly due to the impact of the vaccine and/or due to viral variation which has led to less hyper-inflammation in children with COVID 19.
JAMA : Protecting Children Against Omicron June 202214
- Sophie E. Katz, MD, MPH; Kathryn Edwards, MD2 studies published in JAMA demonstrate that the estimated vaccine effectiveness among children and adolescents with Omicron is considerably lower than in the initial studies, and protection wanes rapidly, especially with novel SARS-CoV-2 variants.15,16 The encouraging message should be that although vaccine protection for children was lower in the Omicron era than with previous variants and that protection wanes rapidly, vaccine effectiveness against hospitalisation remains high and booster doses confer additional protection14
June 2022: Moderna recently announced preliminary results from a trial of its bivalent booster vaccine(mRNA-1273.211), with higher neutralising antibody responses against the ancestral SARS-CoV-2, Beta, and Omicron variants after booster dose
13. Liu B et al. Relative Effectiveness of COVID-19 Vaccination with 3 Compared to 2 Doses Against SARS-CoV-2 B.1.1.529 (Omicron) Among an Australian Population with Low Prior Rates of SARS-CoV-2 Infection The Lancet Preprint. June 2022
14. Katz SE, Edwards K. Protecting Children Against Omicron. JAMA. 2022;327(22):2195–2197.doi:10.1001/jama.2022.7315
15. Fleming-Dutra KE, Britton A, Shang N, et al. Association of prior BNT162b2 vaccination with symptomatic SARS-CoV-2 infection in children and adolescents during Omicron predominance. JAMA. Published online May 13, 2022. doi:10.1001/jama.2022.7493
16. Dorabawila V, Hoefer D, Bauer UE, et al. Risk of infection and hospitalization among vaccinated and unvaccinated children and adolescents in New York after the emergence of the Omicron variant. JAMA. Published online May 13, 2022. doi:10.1001/jama.2022.7319
COVID-19 Vaccine Safety
As at 17 October 202217,18 6,570,029 safety surveys completed
- 55.8% of participants reported no adverse event
- 44.2% of participants reported any adverse event
- 0.9% of participants reported visiting a doctor or emergency department
Myocarditis Pfizer vaccine: take home messages
- Post-market safety surveillance of mRNA COVID-19 vaccines has found an increased frequency of myocarditis and pericarditis most frequently
- in adolescents and younger adults under 30 years of age,
- more frequently in males compared to females, and
- more frequently after the second dose.
- Most within 7 days of vaccination
- Need Investigation with ECG, CXR, Troponin, potentially ECHO or Cardiac MRI
- Majority of cases have been mild and have resolved
- Mild cases may be treated with non-steroidal anti-inflammatory drugs (NSAIDS) for symptomatic relief
- Avoid high intensity exercise if confirmed as a diagnosis
- Seek cardiology advice prior to dose 2
17. AusVaxSafety Covid 19 vaccines https://ausvaxsafety.org.au/safety-data/covid-19-vaccines
18. Australian Government Department of Health and Aged Care COVID-19 vaccine safety report – 20-10-2022 https://www.tga.gov.au/news/covid-19-vaccine-safety-reports/covid-19-vaccine-safety-report-20-10-2022
COVID-19 Vaccine Hesitancy
- Narrative approach – much more than information
- Compassion & Consultation: Listening
- Rights v. responsibilities
- Role of decision-aids (See CoRiCal)19
19. CoRiCal Decision aid https://corical.immunisationcoalition.org.au/
How is COVID-19 Treated?
Doctors will need to review patients’ medications and their current medical conditions to decide if a COVID-19 treatment is suitable for them. The types of COVID-19 treatments that are suitable will also depend on the severity of their COVID-19 illness.
Basic in hospital treatment options include: oxygen for severely ill patients, ventilation for patients who are critically ill and the use of Dexamethasone or other corticosteroids. Antivirals, immune modulators and monoclonal antibodies have also been used.
Antiviral medications can help prevent severe COVID-19 if taken within five days of symptom onset.
These are available for eligible people who are vulnerable to severe disease such as older people, those with comorbidities, people who are immunosuppressed and those who are unvaccinated with a script from a GP.
Available on Pharmaceutical Benefits Scheme (PBS):
- COVID-19 oral antiviral treatments nirmatrelvir and ritonavir (Paxlovid) and molnupiravir (Lagevrio) are available through the PBS for eligible patients.
- Commencing 11 July 2022, the PBS eligibility criteria for COVID-19 oral antiviral treatments Paxlovid and Lagevrio has been expanded.20
20. Australian Government Department of Health Coronavirus (COVID-19) case numbers and statistics Last updated 21 October 2022