COVID-19

What

COVID-19 is an infectious disease caused by the severe acute respiratory coronavirus 2 (SARS-CoV-2) virus. It affects people of all ages. Older adults and people with certain medical conditions have an increased risk of severe disease or death from COVID-19.

Who

COVID-19 vaccination is recommended for people at the highest risk of severe disease such as adults aged 65 years and over, Aboriginal and Torres Strait Islander adults aged 50 years and over and adults aged 18 to 64 years with severe immunocompromise.

How

The COVID-19 vaccination program objective has transitioned from establishing broad population-based immunity against a newly emerged virus to a focus on maintaining protection against severe disease, including from emerging SARS-CoV-2 variants now that COVID-19 is endemic. Based on age and medical risk, certain people are recommended to receive one or two doses of COVID-19 vaccine annually, independent of past vaccination history. Primary course recommendations are no longer specified.

Two doses each year are recommended for:  

• All adults aged ≥75 years

One dose each year is recommended, and a second annual dose can be considered for:  

• Adults aged 18–64 years with severe immunocompromise
• Adults aged 65–74 years with medical risk conditions (including severe immunocompromise)
• Aboriginal and Torres Strait Islander adults aged 50–74 years with medical risk conditions (including severe immunocompromise)

One dose each year is recommended for:

• Adults aged 65–74 years with no medical risk conditions  
• Aboriginal and Torres Strait Islander adults aged 50–74 years with no medical risk conditions

One dose each year can be considered for:

• Children aged 6 months–<18 years with medical risk conditions (including severe immunocompromise)  
• All other adults aged 18–64 years without severe immunocompromise

Pregnant women can consider a dose from 20 weeks gestation in each pregnancy. 

Why

COVID-19 can cause severe illness particularly in older adults, including aged care residents, and in people with medical risk conditions.  Vaccination reduces the risk of severe illness and death from COVID-19.

COVID-19 vaccines available in Australia

The Therapeutic Goods Administration website provides product information for each vaccine, including Comirnaty LP.8.1 vaccines.

See also Vaccine information and Variations from product information for more information.

Dose and route

All currently available COVID-19 vaccines are administered intramuscularly. The dose varies by brand and age. Refer to vaccine details above for further information.

A person who requires 2 priming doses may receive the second vaccine dose earlier than the recommended interval (a minimum of 3 weeks) in exceptional circumstances, such as before starting immunosuppressant therapy, before overseas travel or if someone cannot reschedule vaccination easily (such as in an outreach vaccination program).

Co-administration with other vaccines

People aged ≥5 years

COVID-19 vaccines can be co-administered with other vaccines in people aged ≥5 years.

Studies demonstrate the safety and immunogenicity of co-administration of COVID-19 and influenza vaccines.^46-48 COVID-19 vaccines can also be co-administered with other vaccines if required, including routine childhood, adolescent vaccines and vaccines given in adulthood. 

Replicating mpox vaccines (such as ACAM2000) and mRNA COVID-19 vaccines both carry a small risk of myocarditis, but the risk from non-replicating MVA-BN mpox vaccines remains unknown. If the timing of MVA-BN is not urgent, consider spacing apart MVA-BN mpox vaccine and mRNA COVID-19 vaccines by four weeks, to allow attribution for any adverse reaction. This is particularly relevant for young males or people with specific relevant concerns.

Children aged 6 months to <5 years

For children aged 6 months to <5 years it is preferable to separate administration of COVID-19 vaccine from other vaccines by 7–14 days.

There are limited data on the safety and immunogenicity of co-administration in this age group. Theoretically, co-administration may lead to higher rates of adverse events, including fever. However, COVID-19 vaccines can be co-administered if separation of vaccines would be logistically challenging.

Timing of COVID-19 vaccination

COVID-19 vaccine can be offered once or twice a year to eligible people, with doses spaced approximately 6 months apart, while allowing shorter intervals when clinically appropriate. Although some seasonal patterns have emerged in the last 2 years with primary winter and summary peaks,⁴⁹ seasonality of SARS-CoV-2 circulation is not yet well established and vaccination should not be deferred solely based on the time of year. Optimal vaccine protection is expected to last at least 4–6 months after vaccination.⁵⁰

People with a history of SARS-CoV-2 infection can receive further doses of COVID-19 vaccine as per the recommended schedule. There is no recommended minimum interval between COVID-19 infection and vaccine dose as most people may not know the timing of their last infection due to low community testing rate. While it is safe to vaccinate soon after illness, reinfection risk is lower in the period immediately following infection. Where clinically appropriate, people may consider delaying vaccination for a few months following known infection to optimise their immune response. 

Contraindications

COVID-19 vaccines are contraindicated in people who have had:

• anaphylaxis after a previous dose of a COVID-19 vaccine from the same class
• anaphylaxis after one mRNA COVID-19 vaccine is a contraindication to all mRNA COVID-19 vaccines
• anaphylaxis after any component of that COVID-19 vaccine

Precautions

People with certain cardiac conditions

People with a history of any of the following conditions can receive a COVID-19 vaccine, but advice should be sought from a GP, immunisation specialist or cardiologist about the best timing of vaccination and whether any additional precautions are recommended:

• recent (within the past 3 months) myocarditis or pericarditis
• acute rheumatic fever or acute rheumatic heart disease (with active myocardial inflammation)
• acute decompensated heart failure.

People who develop myocarditis and/or pericarditis after a COVID-19 vaccine should defer further doses and discuss options for further COVID-19 vaccination with their treating doctor.

Current COVID-19 vaccine safety data are extrapolated from large clinical trials of the original and earlier formulation COVID-19 vaccines. Real world data on common local and systemic adverse events for updated vaccines with newer variants (e.g. Comirnaty LP.8.1) are emerging but their adverse event profile is expected to be similar to that of earlier formulations.

Children aged 6 months to <5 years

Following Comirnaty Original vaccination, the most frequently reported adverse events in children aged 6–23 months in the placebo controlled clinical trial were irritability (in about 40-50%), drowsiness (in about 25%), injection site tenderness (in about 15%), and fever (in about 7%).^17,51 Local adverse events occurred at similar frequencies after the first and second dose and were slightly less frequent after the third dose.  

In children aged 2–4 years, adverse events occurred at similar frequencies after the first, second and third doses.⁵¹ The most frequently reported adverse events in the clinical trial were injection site pain and fatigue (in about 25–30%). Fever was reported in about 5% of recipients. 

Children aged 5–11 years

Following Comirnaty Original vaccination, the most commonly reported adverse event in children aged 5–11 years in the placebo controlled clinical trial was injection site pain (in about 70–75%), followed by fatigue (in about 35%) and headache (in about 20–30%).¹⁸ Fever occurred in 3% of children after the first dose and 7% of children after the second dose. A large population-based study during the Omicron period showed robust COVID-19 vaccine safety profile in this age group with no new significant adverse events.⁵²

People aged ≥12 years

A phase 2/3 trial among individuals aged ≥12 years reported fatigue (in about 35-60%) and headache (in about 25 to 45%) as the most common adverse events following Comirnaty Omicron XBB.1.5 vaccination. Local and systemic reactions were mostly mild to moderate in severity, similar to earlier formulations.⁵³ A meta-analysis of post marketing studies on Comirnaty vaccines among immunocompromised adolescents and young adults found overall 28% had a local reaction (pain, swelling, itching and erythema) while the likelihood of any systemic adverse event was higher after the second dose than after the first dose (13% vs 9%).⁵⁴

Anaphylaxis after COVID-19 vaccines

Anaphylaxis after COVID-19 vaccines is rare and occurs at a similar rate to other common vaccines. In a study that included Comirnaty Original and Spikevax Original, the overall rate of anaphylaxis was around 10 per million doses.⁵⁵  

Myocarditis and Pericarditis

Myocarditis and/or pericarditis following vaccination with a COVID-19 vaccine are very rare but have been reported following receipt of all currently available COVID-19 vaccines. The highest incidence has been reported in adolescent and young adult males after a second dose of an mRNA vaccine (e.g. Comirnaty), although cases have been reported in male and female adults of all ages and after any dose of a COVID-19 vaccine.^7,8 No events of myocarditis or pericarditis were reported in clinical trials after vaccination in children aged 6 months–11 years^16,18, and no cases of myocarditis were reported in children aged 6 months–5 years in a large national surveillance system.^16-18

Cases with COVID-19 vaccine associated myocarditis are generally mild with lower frequency of cardiovascular complications compared to those with myocarditis from other causes.^56-58 Some patients have reported persistent symptoms with cardiac imaging abnormalities detected months after diagnosis, though there is improvement over time. The longer-term clinical significance of these findings is not yet known.⁵⁶

It is recommended that all COVID-19 vaccine recipients be made aware of the potential signs and symptoms of myocarditis or pericarditis and be counselled to seek medical attention if they develop. [See Adverse events following immunisation]

Safety of COVID-19 vaccines during pregnancy or breastfeeding

mRNA COVID-19 vaccines are safe in pregnancy.^59-61 

The adverse event profile of pregnant women is similar to that of non-pregnant women following vaccination with an original mRNA COVID-19 vaccine.^62,63 Pregnant women are slightly more likely to report injection site pain, and less likely to report generalised symptoms such as fever or tiredness.

Coronavirus disease (COVID-19) is caused by the severe acute respiratory coronavirus 2 (SARS-CoV-2), a single-stranded RNA betacoronavirus first identified in December 2019.  

SARS-CoV-2 contains 4 main structural proteins: spike (S) glycoprotein, small envelope (E) glycoprotein, membrane (M) glycoprotein and nucleocapsid (N) protein.⁶⁴ Most COVID-19 vaccines target the spike protein which allows the virus to enter cells. 

Since its discovery, variant strains have progressively become dominant due to advantages in transmissibility or immune escape from immunity acquired from prior infection or vaccination. Future virus mutations are anticipated, leading to new SARS-CoV-2 variants with immune escape, and seasonal factors.^65-67

Since 2024, Omicron is the only variant circulating globally.⁶⁸ Previous variants of concern (e.g. Alpha, Beta, Gamma, Delta) and the ancestral strain have largely disappeared. Numerous sub-lineages of Omicron have caused distinct global waves of infection.⁶⁹

Pathogenesis

In most people, SARS-CoV-2 primarily infects cells lining the upper airway and causes mild to moderate disease. Individuals with severe disease develop an infection of the lower respiratory tract causing pneumonia and may have poor or mistimed immune responses that cause both local inflammatory responses and a systemic pro-inflammatory state that leads to severe immunopathology.⁷⁰ 

People at increased risk of severe COVID-19 disease

Risk factors for severe disease

Older age 

Older age is by far the strongest risk factor associated with morbidity and mortality from COVID-19.^9-11,71,72 A study that assessed the mortality risk from COVID-19 among people who have received a primary course and further dose found a 30-fold greater risk of death in a person aged 80 compared with a person aged 50.⁹ 

Medical conditions 

Medical conditions, including severe immunocompromise, also independently increase the risk of severe disease but to a lesser extent than age.⁷³ Populations with medical risk conditions are particularly heterogeneous and there are highly variable risk estimates across the medical risk conditions for severe COVID-19. For a list of these conditions, See Table: Example conditions associated with increased risk of severe outcomes from COVID-19.

Pregnancy

Unvaccinated pregnant women with COVID-19 have an increased risk of severe disease compared with unvaccinated non-pregnant women of reproductive age with COVID-19.^74,75 This risk appears to be substantially reduced during the Omicron period in women who have been vaccinated.^44,76

Transmission

SARS-CoV-2 is spread via respiratory droplets or aerosols generated through breathing, talking or coughing.⁷⁷ Airborne viral particles may be inhaled, contact mucous membranes in the mouth, eyes, or nose, or land on surfaces and cause infection through contact with contaminated surfaces which are transferred to the body.

Symptoms of COVID-19 disease

The most common symptoms reported following infection with the SARS-CoV-2 Omicron variant are runny nose, sore throat, sneezing and headache.^78,79 Some features of COVID-19 which were associated with previous variants such as fever, loss of smell and persistent cough appear to be less commonly reported with Omicron infection. The potential consequences of severe COVID-19 include respiratory failure, sepsis, thromboembolism (blood clots), and multiorgan failure, including injury of the heart, liver or kidneys, and death.⁸⁰  

Severe disease and hospitalisation is less common with the Omicron variant than with previous variants, and this may be partially due to accumulating immunity from a combination of vaccination and prior infection.⁸¹

The incubation period after exposure to SARS-CoV-2 (Omicron) is most commonly 3 days, but can be up to 14 days.⁸²  

Complications and sequelae of COVID-19 disease

Severe COVID-19 can be fatal. An estimate of infection fatality rate (IFR) early during the Omicron period in a Danish study was 6·2 (95% CI: 5·1–7·5) per 100 000 infections.⁸³ 

A range of metabolic, cardiovascular, respiratory, immunological and neurological sequelae following COVID-19 have been reported in the literature.^84-88  

Post-COVID-19 condition (‘long COVID‘) is currently not well defined, but generally consists of persistent symptoms that develop during or after COVID-19, continue for greater than 3 months after the onset of the illness, and are not explained by an alternative cause.⁸⁹ This can consist of various physical symptoms (e.g. fatigue, dyspnoea, chest pain, and cough), cognitive symptoms (memory and concentration issues) and psychological symptoms (anxiety, depression, post-traumatic stress disorder).

The prevalence of post-COVID-19 condition is highly variable due to differing definitions. A systematic review and meta-analysis including over 735,000 participants reported that 45% of COVID-19 survivors experience a range of unresolved symptoms at 4 months.⁹⁰ Risk factors for post-COVID-19 condition may include the presence of comorbidities, prior hospitalisation from COVID-19, female sex, older age, high body mass index and smoking.⁹¹  

Vaccinated people have a significantly lower risk of post-COVID-19 condition (OR: 0.57; 95% CI: 0.43-0.76).⁹¹

COVID-19 disease in Australia

During the COVID-19 pandemic, Australia experienced widespread SARS-CoV-2 transmission and significant disease burden alongside the rest of the world. Serosurveys indicated that a large proportion of the Australian population had experienced COVID-19 by December 2022, with the highest proportion among adults aged 18–29 years where approximately 82% of the population had serological evidence of infection.⁹² Similarly approximately 80% of unvaccinated children had experienced COVID-19 by August 2022.⁹³

In the post-pandemic period, COVID-19 associated mortality have declined significantly, however COVID-19 remains the leading cause of acute respiratory infection mortality across 2023–2025 in Australia, disproportionately affecting older age groups.^94,95

Original COVID-19 vaccines were directed at, or contained, the ancestral virus spike protein only. As SARS-CoV-2 has evolved, newer COVID-19 vaccines have been developed to target both the original strain of the virus and newer, more immune-evasive variants, based on advice from the World Health Organization Technical Advisory Group on COVID-19 Vaccine Composition.⁹⁶ Many updated formulations differ from the original formulation only in the specific spike protein antigen used, and therefore updated formulation (e.g. LP.8.1) COVID-19 vaccines were approved by regulatory agencies, such as the Therapeutic Goods Administration (TGA), after extrapolating vaccine efficacy data from large phase 3 clinical trials of prior COVID-19 vaccines.

Currently available Comirnaty LP.8.1 vaccines are formulated against the Omicron LP.8.1 subvariant.

Omicron-based COVID-19 vaccines

Vaccine efficacy and effectiveness

LP.8.1 adapted vaccine effectiveness studies are emerging. A large Danish observational cohort study estimated that the LP.8.1 vaccine effectiveness was around 61% against COVID-19 hospitalisation and 70% against COVID-19 death in adults aged ≥65 years. Vaccine effectiveness against hospitalisation appeared to decline gradually over the 4 months after vaccination.⁹⁷ A US study in adults based on the Veterans Affairs Healthcare System estimated a similar overall vaccine effectiveness of 56% of the LP.8.1-adapted vaccine against mild-to-moderate COVID-19 outcomes.⁹⁸

Previous studies have suggested that the effectiveness of vaccines matched to the currently circulating Omicron variants appears to be higher than mismatched vaccines, although protection against severe outcomes can still be maintained despite some antigenic mismatch.^5,99

Vaccine immunogenicity

Two ongoing phase 3b/4 studies evaluating LP.8.1-adapted mRNA vaccines found that both vaccines elicited robust increases in neutralising antibodies against LP.8.1 and other emerging variants by day 29 in older adults and individuals at high risk of severe COVID-19.¹⁰⁰ Another study looking at humoral immunity of 56 adults following KP.2 vaccination reported enhanced neutralisation against vaccine-matched KP.2 variant but significant reduction in neutralising antibody response against antigenically drifted variants such as LP.8.1, NB.1.8.1 and XFG, highlighting the potential immune escape capability of newer variants.¹⁰¹

Original COVID-19 vaccine

In children aged 5–11 years without evidence of previous SARS-CoV-2 infection, the 10 µg dose of paediatric Comirnaty was 90.7% effective (95% CI: 67.7–98.3%) in preventing laboratory-confirmed symptomatic COVID-19 in the pre-Omicron era.¹⁸

Comirnaty Original had a vaccine efficacy of 82.4% (95% CI -7.6–98.3%) against confirmed COVID-19 due to Omicron in children aged 2–4 years, and 75.6% (95% CI -369.1–99.6%) in children aged 6–23 months.⁵¹  

In the pivotal efficacy trial among adults aged ³16 years, a 2-dose regimen of Comirnaty Original was 95% effective (95% CI: 90.3–97.6%) in preventing laboratory-confirmed COVID-19.¹⁰²

Currently available COVID-19 vaccines are presented as multi-dose vials or single use prefilled syringes. For guidance on handling of multi-dose vials, refer to Administration of vaccines.

Multi-dose mRNA COVID-19 vaccine vials are initially stored frozen at ultra-cold temperatures and once thawed can be stored in a fridge for a certain period before use. Requirements differ by vaccine brand and vial; for more information see COVID-19 vaccines in Australia - Poster.

General advice:

• Thawed vials of frozen vaccine should not be refrozen.
• Do not shake the vaccine vials.
• Minimise exposure to room light and avoid direct sunlight and ultraviolet light.
• Once a multi-dose vial is punctured, use prepared doses within 6 hours.

For general information on vaccine storage, see the National Vaccine Storage Guidelines Strive for 5.¹⁰³

COVID-19 is a notifiable disease in all states and territories in Australia.

The Communicable Diseases Network Australia provides national guidelines and the State and territory public health authorities can provide local advice about the public health management of COVID-19, including management of cases and their contacts.

Impact of vaccination on future COVID-19 testing

Receiving a COVID-19 vaccine will not affect the results of nucleic acid (PCR) testing or rapid antigen testing for diagnosis of SARS-CoV-2 infection. However, as vaccines induce protective antibodies against the spike protein, this may result in serological testing detecting antibody to the spike protein. Vaccination will not affect the results of anti-nucleocapsid antibody testing.

Post-exposure prophylaxis

COVID-19 vaccines are not recommended for post-exposure prophylaxis. No data are available to support such use.

The product information for Comirnaty state that the recommended interval between primary course doses is 3 weeks and at least 3 months between primary course and further doses.

ATAGI recommends an 8-week interval between priming doses and an approximate 6-month spacing between annual doses, noting that shorter intervals may be appropriate based on individual circumstances.

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