WHAT are SARS-Cov-2 AND COVID-19?

 

COVID-19 is a disease caused by a novel coronavirus, SARS-CoV-2, that was first reported in December 2019 in the city of Wuhan, central China.

Coronaviruses are a large group of viruses which affect both mammals and birds, and they cause different diseases depending on the species infected. Human coronaviruses usually cause a mild, common cold-like illness which passes in a few days.

As part of the replication process of viruses, errors or mutations occur which can be minor, but they may also prove to be an advantage to the virus. This may be evident through increased transmissibility, virulence or, in the case of SARS-CoV-2, ability to jump species (a spill-over event). There is relatively recent history of this with two previous extensive outbreaks of coronavirus infections of animal origin spreading to humans - SARS (in 2002-3) and MERS (from 2012 and continuing).  

The virus can spread from person to person through:

  • Contact with an infectious person through aerosols which are expelled through talking, shouting or singing, particularly in indoor setting with inadequate ventilation (including in the 48 hours before symptoms, if any, appear).
  • Contact with droplets from an infected person’s saliva (cough, kiss) or discharge from the nose (sneeze).
  • Touching objects or surfaces (like doorknobs or tables) that have droplets from an infected person, and then touching your mouth or face – this is a less common mode of transmission.

WHAT ARE THE SYMPTOMS?

COVID-19’s incubation period, the time between exposure to the virus and symptoms appearing, ranges from 1 to 14 days, but most people will develop symptoms within 5 to 6 days of exposure. Australia’s national COVID-19 public health guidelines use a 14-day incubation period to guide advice on public health measures, such as quarantine and isolation.

It has been estimated that around 17% of infections are asymptomatic. 

COVID-19 can range from an asymptomatic or mild illness to pneumonia, with symptoms that can include:

  • fever, fatigue
  • respiratory symptoms, including coughing, sore throat, shortness of breath, chest pain, runny or blocked nose
  • headache
  • muscle and/or joint pains
  • nausea, diarrhoea, vomiting
  • loss or altered sense of smell &/or taste
  • loss of appetite

WHERE IS IT FOUND?

COVID-19 virus is currently a risk world-wide, however some Pacific islands have reportedly remained virus-free.

REDUCING THE RISK OF TRANSMISSION

When you are well

  • If available, have your COVID-19 vaccinations.
  • Physical distancing 1.5 metres away from others wherever possible and follow local public health guidelines which may include wearing masks, registering at venues and other protocols.
  • Wash your hands often with soap and water or use alcohol-based hand sanitisers.
  • Avoid touching your eyes, nose and mouth.
  • Clean and disinfect surfaces you use often such as bench tops, desks and doorknobs

When you are sick

It is important that you stay at home if you feel unwell and continue to use good hygiene practice.  If you have cold or flu-like symptoms, even if they are mild, you should get tested for COVID-19 and isolate until you have a negative test result (or as directed by the public health unit).

HOW IS COVID-19 TREATED?

Most people with COVID-19 disease will experience a mild to moderate respiratory illness and recover without requiring any specialist treatment. Rest, fluids and analgesia are generally the mainstays of treatment, however new therapies are being developed and the management of the disease remains under review. In cases of severe COVID-19 and for people at risk of complications, hospitalisation with supportive and antiviral treatment may be required.

WHAT IS COVID-19 VACCINATION?

The Australian Government’s COVID-19 free vaccination program for citizens, residents and most visa holders began in February 2021. The vaccines being used in Australia are effective and aimed at stopping the spread of the disease and reducing COVID-19 virus-related harm, preventing serious illness and loss of life, as much as possible. They are inactivated vaccines (not live) which are based on a harmless, non-replicating part of the virus to provoke an immune response in our bodies which will be remembered if we are ever exposed to the virus in the future.

VACCINE SCHEDULES

The Australian Technical Advisory Group on Immunisation (ATAGI) currently recommends that the two available COVID-19 vaccines – AstraZeneca and Pfizer - are administered to people over the age 18 years. Studies are underway on the suitability of giving the vaccines to adolescents and children.

COVID-19 Vaccine AstraZeneca is now to be used for adults over the age of 50 years and           (Pfizer/BioNTech) Comirnaty vaccine is preferred for adults aged 18- 50 years.

COVID-19 Vaccine AstraZeneca has a 2-dose vaccination schedule – minimum 4 weeks apart, but the recommendation in Australia is for the second dose to be given 12 weeks after the first dose. 

Comirnaty is a 2-dose vaccination schedule given 21 days apart.

LEVEL OF PROTECTION

Both Comirnaty and COVID-19 Vaccine AstraZeneca currently require a 2-dose course for the best immune response. Whilst partial protection against COVID-19 may be provided as soon as 12 days after the first dose, this protection is likely to be short-lived. The second dose encourages the body to create stronger and longer-lasting protection (immunity) against SARS-CoV-2, the virus that causes COVID-19. 

Individuals are not considered to be fully protected until 14 days after their second dose of the COVID-19 vaccines. 

Studies continue into the duration of protection offered by the vaccines and the likely impact emerging virus variants may have on this.

PREGNANCY & BREASTFEEDING

The Australian government Department of Health’s decision guide for women who are pregnant, breastfeeding, or planning pregnancy advises that, while COVID-19 vaccines have not yet been studied in detail in breastfeeding women, there are no concerns about their safety for this group or their babies, and there is no evidence breastfeeding women have an increased risk of complications compared to women who are not breastfeeding. So, if you are breastfeeding you can receive Comirnaty or COVID-19 Vaccine AstraZeneca at any time. You do not need to stop breastfeeding before or after vaccination.

Vaccination does not affect fertility and getting vaccinated before conceiving means you will have some protection against COVID-19 throughout your pregnancy. If you become pregnant after your first dose, you might choose to have the second dose during pregnancy or delay it until after delivery. You don’t need to avoid becoming pregnant before or after vaccination.

COVID-19 vaccines are not routinely recommended for women during pregnancy, however the advice is that a woman, in discussion with her treating health professional, may consider vaccination if the potential benefits outweigh any potential risks. This may be the case if the woman has medical risk factors for severe COVID-19 or is a high-risk worker who has contact with confirmed COVID-19 cases.

POSSIBLE SIDE EFFECTS

As with any vaccine, some temporary side effects may occur after receiving a COVID-19 vaccine.

Following COVID-19 Vaccine AstraZeneca, side effects may include:

  • injection site pain or tenderness
  • tiredness
  • headache
  • muscle pain
  • fever and chills

Most side effects are mild and temporary, going away within 1-2 days. As with any medicine or vaccine, there may be rare and/or unknown side effects.

COVID-19 Vaccine AstraZeneca rare side effect - TTS

COVID-19 Vaccine AstraZeneca has been associated with a rare side effect (4-6 cases per million doses) called Thrombosis with thrombocytopenia syndrome (TTS), also known as Vaccine-induced prothrombotic immune thrombocytopenia (VIPIT), which appears to be more frequently reported following the first dose. This thrombotic syndrome differs from common venous thrombo-embolic disease in that it is immune- mediated, rather than associated with the commonly known risk factors for thrombosis. It tends to occur in unusual sites resulting in cerebral venous sinus thrombosis and splanchnic vein thrombosis, both of which carry significant morbidity and mortality. TTS following COVID-19 Vaccine AstraZeneca vaccination has occurred mostly in younger vaccine recipients (under 60 years of age).

Potential side effects after vaccination with Comirnaty:

Mostly mild to moderate & short-lasting.

  • Very common side effects - may affect more than 1 in 10 people: Injection site pain & swelling, tiredness, headache, muscle pain, joint pain, chills, fever.
  • Uncommon side effects - may affect up to 1 in 100 people: Enlarged lymph nodes, feeling unwell, pain in limb, insomnia, injection site itching.
  • Rare side effects - may affect up to 1 in 1,000 people: temporary one sided facial drooping

Very rare side effects - in US seen in approximately 11 cases per 1 million vaccine doses: Anaphylaxis

EFFICACY:

AstraZeneca – Studies have shown approximately 62% effectiveness for 2 standard doses across age groups 18 years of age and above. (This may vary (62-90%) based on age, dose and time between doses)

Comirnaty - Studies determined 95% vaccine efficacy across all age groups from 16 years of age up to 75 years and older.

BOOSTER DOSES:

The length of protection offered by the 2 initial doses is still being studied in clinical trials. 

 

Further information can be found at:

 

 

References:

Australian Government Department of Health: https://www.health.gov.au/initiatives-and-programs/covid-19-vaccines

RACGP: Australian study determines true asymptomatic COVID rate:   https://www1.racgp.org.au/newsgp/clinical/australian-study-determines-true-asymptomatic-covi

Health Direct: Symptoms of COVID-19 and how the virus spreads | healthdirect

Australian government, Dept. of Health. COVID-19 vaccination decision guide for women who are pregnant, breastfeeding, or planning pregnancy: https://www.health.gov.au/resources/publications/covid-19-vaccination-covid-19-vaccination-decision-guide-for-women-who-are-pregnant-breastfeeding-or-planning-pregnancy

Melbourne Vaccine Education Centre, Thrombosis with thrombocytopenia syndrome: https://mvec.mcri.edu.au/references/thrombosis-with-thrombocytopenia-syndrome/

World Health Organisation: https://www.who.int/health-topics/coronavirus#tab=tab_1