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 2 available COVID-19 vaccines – Pfizer and Moderna - can be administered to people over the age 12 years. Studies have been carried out, and are continuing, into the suitability of giving the vaccines to younger children. 

(AstraZeneca) Vaxzevria is now to be used for adults over the age of 60 years, while the (Pfizer/BioNTech) Comirnaty vaccine and Moderna Spikevax vaccines are for all eligible people aged over 12 years, as appropriate. In the event of outbreaks and unavailability of alternate vaccines, Vaxzevria can be given to a wider age group (ATAGI 2021).

AstraZeneca's Vaxzevria 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. 

Pfizer/BioNTech's Comirnaty vaccine has a 2-dose vaccination schedule given 21 days apart.

Moderna's Spikevax also has a 2-dose vaccination schedule given 28 days apart.

LEVEL OF PROTECTION

ComirnatyVaxzevria and Spikevax  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 and is not as robust, particularly against emerging virus variants. 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 will have on this.

PREGNANCY & BREASTFEEDING

On August 18, 2021, ATAGI and the Royal Australian and New Zealand College of Obstetricians and Gynaecologists (RANZCOG) updated their joint statement in which they recommended that 'pregnant women are routinely offered the mRNA vaccines, Comirnaty (Pfizer) and Spikevax (Moderna), at any stage of pregnancy. This is because the risk of severe outcomes from COVID-19 is significantly higher for pregnant women and their unborn baby'. 

While the timing of the vaccination during pregnancy should be discussed with your health professional, the joint statement advises that 'Global surveillance data from large numbers of pregnant women have not identified any significant safety concerns with mRNA COVID-19 vaccines given at any stage of pregnancy. There is also evidence of antibody in cord blood and breast milk, which may offer protection to infants through passive immunity'. 

There is also positive news for women who are planning pregnancy or who have recently become pregnant that they do not need to delay vaccination or avoid becoming pregnant after vaccination’.

POSSIBLE SIDE EFFECTS

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

Following Vaxzevria, side effects may include:

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

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

Vaxzevria rare side effect - TTS

Vaxzevria 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 Vaxzevria vaccination has occurred mostly in younger vaccine recipients (under 60 years of age).

Advice from the Australian Technical Advisory Group on Immunisation (ATAGI) on TTS in Vaxzevria recipients is that these clotting complications have occurred between day 4 and 26 after vaccination. The Group states that ‘Consumers should be particularly alert to severe, persistent headaches that are different to their "usual" pattern and do not settle with paracetamol or other painkillers. If these symptoms occur consumers should seek medical advice as soon as possible. Anyone attending their GP or a hospital with any concerns should let their treating clinician know the details of the vaccine they received.’ Read more

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 4.7 per million vaccine doses: Anaphylaxis

Side effects following vaccination with Spikevax: 

Studies from the USA, where the vaccine has been in use for several months, show that most side effects occur within 24-48 hours post-vaccination are mild-moderate. They may be more acute after the second dose and include: 

  • Pain, redness and swelling at injection site
  • Tiredness, headache
  • Muscle pain
  • Chills, fever
  • Nausea

Very rare side effects - in the USA seen in approximately 2.5 per million vaccine doses: Anaphylaxis

What is known about reports of heart inflammation following vaccination with mRNA vaccines?

There have been some overseas reports of inflammation of the heart or its surrounding membrane (myocarditis and pericarditis) that have occurred, mainly in teenage boys, usually within 7 days of receiving the second dose of a mRNA vaccine – most individuals responded to treatment and rest. The TGA is monitoring the situation for a causal link to the vaccination, but does note that both conditions ‘often occur following a viral infection and most cases are mild with no long-term effects. Severe cases may cause damage to the heart muscle although this is very rare.’ While investigations continue, both in Australia and overseas, the TGA advises ‘people to report symptoms that could suggest myocarditis or pericarditis such as of chest pain, shortness of breath and palpitations, particularly after the second dose' of a mRNA vaccine.

In August, 2021, ATAGI  published advice on the topic: 'Guidance on Myocarditis and Pericarditis after mRNA COVID-19 Vaccines'.

EFFICACY:

Vaxzevria – 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.

Spikevax - Data from the CDC in the US show the vaccine was approximately 94% effective in preventing laboratory-confirmed COVID-19 infection in people aged 18 years and older after 2 doses.

BOOSTER DOSES:

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

CO-ADMINISTRATION WITH OTHER VACCINES: 

The Australian Technical Advisory Group on Immunisation (ATAGI) has advised that any vaccines, including influenza, should be given at least 7 days before or after Comirnaty, Vaxzevria and Spikevax vaccines, based on the current lack of data relating to any safety issues or interference with immune responses when given together. There are some occasions where on clinical advice the interval can be shortened or even allow for co-administration. (ATAGI 2021)

 

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

Joint statement between RANZCOG and ATAGI about COVID-19 vaccination for pregnant women: https://www.health.gov.au/news/joint-statement-between-ranzcog-and-atagi-about-covid-19-vaccination-for-pregnant-women  

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