Comirnaty (Pfizer)

Find out more about the Pfizer COVID-19 vaccine, including how it works, who it's recommended for and advice about potential side effects.

Approval for use in Australia

Comirnaty (Pfizer) is approved for use in people aged 12 years and over. 

The TGA provisionally approved it for use in Australia on 25 January 2021 (for 16 years and over) and 22 July 2021 (for 12 years and over).

In Australia's vaccine rollout, the Pfizer vaccine is now available for all people aged 12 years and over.

Dose schedule

You need 2 doses of the Pfizer vaccine, given between 3 and 6 weeks apart. You may not be fully protected against COVID-19 until 7 to 14 days after your second dose. 

Find out more about booster doses for people aged 18 years and older and third doses for people with severe immunocompromise.

What's in the Pfizer vaccine

Pfizer is a messenger RNA (mRNA) vaccine. This type of vaccine uses a genetic code called RNA to make your body's cells produce the coronavirus’ specific spike protein.

Your immune system cells then recognise the spike protein as a threat and begin building an immune response against it. The RNA from the vaccine does not change your DNA in any way, and your body quickly breaks it down. 

Pfizer does not contain any live virus, and it cannot give you COVID-19. 

This video from John Hopkins Bloomberg School of Public Health explains how mRNA vaccines work. 

You can read the full Cominarty Consumer Medicine Information document on the TGA site for more details (click 'I accept' to see the PDF). 

Common side effects

As with any vaccine, you may have some temporary side effects after receiving Pfizer. This shows your immune system is working.

Common side effects after Pfizer include:

  • injection site pain or swelling
  • tiredness
  • headache
  • muscle or joint pain
  • fever and chills.

Most side effects are mild and go away within 1 to 2 days. AusVaxSafety data shows that side effects are more common after the second dose. 

Rare side effects

Myocarditis or pericarditis in young people

In rare cases, myocarditis (inflammation of the heart) and pericarditis (inflammation of the membrane around the heart) can develop after vaccination with Pfizer. 

Most cases have mild symptoms and recover well. 

The TGA reports that these rare effects on the heart typically occur:

  • within 10 days of vaccination
  • particularly after the second dose
  • more often in men under 30.

Contact a doctor or go to hospital immediately if you develop any of the following symptoms after a Pfizer vaccination: 

  • chest pain
  • pressure or discomfort in the chest
  • irregular, skipped heartbeats or ‘fluttering’
  • fainting
  • shortness of breath
  • pain when breathing.

Low risk of developing myocarditis or pericarditis

The risk of developing myocarditis or pericarditis is very low.

In the US, reported rates in males were 10 cases per million after first doses, and 67 cases per million after second doses. The TGA is monitoring the risk in the Australian population.

Fact sheets

We have printable guidance on myocarditis and pericarditis after mRNA COVID-19 vaccines

The Melbourne Vaccine Education Centre has a page on myocarditis and pericarditis that includes an explanatory video.

Injection technique unlikely to cause myocarditis

ATAGI does not consider injection technique to cause adverse events because most myocarditis cases occur after the second dose. If accidentally injecting into a blood vessel was a factor, cases would occur equally after both doses.

Risks and benefits

The benefits of vaccination with Pfizer greatly outweigh the risk of side effects.  

People who are not recommended to have the Pfizer vaccine

It's not recommended that you have the Pfizer vaccine if you have had:

  • a severe allergic reaction (anaphylaxis) to a previous dose of the vaccine
  • anaphylaxis after exposure to any component of the vaccine, including polyethylene glycol (PEG)
  • myocarditis and/or pericarditis attributed to a previous dose of the vaccine
  • any other serious adverse event attributed to a previous dose of the vaccine.

Patient information

Our patient resources include fact sheets about Pfizer and what to expect after your shot. 

COVID-19 vaccination – Patient resources

This collection contains resources for patients receiving a COVID-19 vaccination.

Last updated: 
2 November 2021

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