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COVID-19 vaccine weekly safety report - 03-06-2021

The Therapeutic Goods Administration (TGA) closely monitors suspected side effects (also known as adverse events ) from the use of COVID-19 vaccines. Importantly, adverse events reported to the TGA are often not caused by the vaccine itself. Learn more about causality.

Learn about the TGA’s COVID-19 vaccine safety monitoring and reporting activities or report a suspected side effect.


  • The most frequently reported suspected side effects associated with Comirnaty (Pfizer) and AstraZeneca COVID-19 vaccines continue to be events that were seen in the clinical trials, and are commonly experienced with vaccines generally.
  • Eight additional cases of blood clots with low blood platelets have been assessed as thrombosis with thrombocytopenia syndrome (TTS) likely to be linked to the AstraZeneca vaccine. When assessed using the United Kingdom (UK) case definition, four cases are confirmed and four are deemed probable TTS. This brings the total number of confirmed and probable TTS cases in Australia to 41.

Reported side effects for COVID-19 vaccines

Gathering reports of adverse events following immunisation (AEFI) is just the first step in determining whether or not the effect is related to the vaccine and whether a significant safety issue is involved. Learn more about how the TGA identifies and responds to safety issues.

In the week of 24-30 May 2021 we received 1825 AEFI reports for COVID-19 vaccines.

Total adverse event reports to 30 May 2021

Reporting rate per 1000 doses
Total AEFI reports received
Total doses administered
Total reports for AZ vaccine
Total reports for Comirnaty
Total reports for brand not specified

Reporting rates per 1000 doses by jurisdiction

Australian Capital Territory
New South Wales
Northern Territory
South Australia
Western Australia

Most commonly reported vaccine side effects

The AEFI most commonly reported to the TGA following COVID-19 vaccines are side effects that are observed with vaccines generally. They include headache, muscle and joint pain, fever and injection site reactions.

The most common reactions reported for the AstraZeneca COVID-19 vaccine in the week of 24-30 May 2021 were headache, fever, muscle pain, fatigue and chills.

The most common reactions reported for the Comirnaty (Pfizer) COVID-19 vaccine in the week of 24-30 May 2021 were headache, muscle pain, lethargy, joint pain and nausea.

This week we focus on dizziness and fainting as side effects relating to COVID-19 vaccination.

Dizziness and fainting following vaccination

Dizziness, feeling faint and fainting (also known as syncope) are expected side effects that sometimes occur following vaccination and other procedures involving an injection.

The TGA has received reports of dizziness and/or fainting following use of both the AstraZeneca and Pfizer COVID-19 vaccines. To 31 May 2021, observed reporting rates of these side effects are as follows:

  • 10 cases of fainting and 58 cases of dizziness per 100,000 doses for the AstraZeneca vaccine
  • 12 cases of fainting and 73 cases of dizziness per 100,000 doses of the Pfizer vaccine.

When timing was reported, most of these side effects occurred within 24 hours of vaccination.

Fainting is a well-recognised stress-related reaction to vaccination and was commonly reported following the human papillomavirus vaccine Gardasil in teenagers. While most reactions are mild and people recover quickly without further problems, sometimes fainting may relate to a more serious underlying condition, particularly in older age groups. Allergic reactions, including anaphylaxis, can also cause dizziness and fainting. While these reactions are rare, it is important to report them to a health professional if they occur after vaccination.

Adverse events of special interest

The TGA, like other vaccine safety monitoring programs around the world, closely monitors for adverse events of special interest (AESI). This monitoring helps us to confirm the safety profile of COVID-19 vaccines, particularly with respect to possible side effects that may occur rarely. We conduct analyses to compare the number of reports of these events against the expected rate in the general population. If the observed reporting rate for an adverse effect is above the expected reporting rate, the TGA conducts a targeted review to determine the need for regulatory action or further investigation.

Adverse events of special interest that we are monitoring for both vaccines include:

  • clotting disorders without thrombocytopenia (low platelets) including stroke, pulmonary embolism and deep vein thrombosis
  • anaphylaxis
  • thrombocytopenia without thrombosis
  • seizures
  • acute cardiac injury, for example myocarditis and pericarditis, heart failure and cardiogenic shock, arrhythmia
  • facial weakness or paralysis, for example Bell’s palsy
  • loss of sense of taste or smell (also called ageusia or anosmia)
  • Guillain-Barre syndrome.

Some of these adverse events are being monitored because of a theoretical link to COVID-19 disease such as stroke, pulmonary embolism, deep vein thrombosis and loss of sense of taste or smell. Other events, including Guillain-Barre syndrome, myocarditis and pericarditis, Bell’s palsy and seizures, are being monitored because they have been observed with other vaccines.

AstraZeneca COVID-19 vaccine

We continue to receive reports of side effects to the AstraZeneca vaccine as it becomes more widely available in Australia. The reports are generally consistent with what is being observed internationally.

Thrombosis with thrombocytopenia syndrome (TTS)

Thrombosis with thrombocytopenia syndrome (TTS) is a rare event involving serious blood clots with a low blood platelet count. TTS is triggered by the immune system’s response to the AstraZeneca vaccine and is different from other clotting conditions. The TGA and other medicines regulators around the world continue to monitor and investigate this issue.

As previously reported, the TGA determines whether a report is likely to represent TTS by assessing cases against a consistent set of criteria, based on the case definitions established by the UK’s Medicines and Healthcare products Regulatory Agency.

Since last week’s report, a further four reports of blood clots and low blood platelets have been assessed as confirmed TTS likely to be linked to the AstraZeneca vaccine. These were in a 40-year-old woman from Victoria who is being treated in NSW, a 70-year-old woman from Victoria, an 82-year-old woman from NSW and a 70-year-old man from Queensland.

In addition, there were four cases classified as probable this week. These were in a 72-year-old man from South Australia, a 61-year-old female from NSW and a 73-year-old man and 67-year-old woman, both from Queensland.

This takes the total Australian reports of cases assessed as TTS following the AstraZeneca vaccine to 31 confirmed cases and 10 probable cases. Based on the most recent information available to us:

  • 23 have been discharged from hospital and are recovering
  • four have left hospital but require outpatient medical care
  • 13 patients remain in hospital
  • one patient died in hospital.

Nine of these 41 cases were more serious and required treatment in intensive care for a period of time. The most recent information we have indicates that four patients remain in hospital, while four have returned home. One of the newly confirmed patients is currently critically unwell and is in intensive care. As previously reported, a 48-year-old woman from NSW with confirmed TTS sadly died while in intensive care. We recognise the terrible impact that this has had for the person’s family and loved ones and extend our sincere condolences.

When we compare the confirmed and probable TTS cases reported in Australia to those reported by overseas regulators, it appears that a smaller proportion of Australian cases are of a very serious nature, involving unusual blood clots, such as cerebral venous sinus thrombosis (CVST) which occur in the brain or or clots in major abdominal veins, including those in the spleen or liver. These are referred to as 'Tier 1' cases according to the United States Centers for Disease Control and Prevention (CDC) criteria and are defined as clots in an unusual location such as the brain or abdomen and a low platelet count with or without a positive test for antibodies that activate platelets (anti-PF4 antibodies). From what we have seen so far, Australian cases seem to represent a wider spectrum of disease with more blood clots in common locations such as deep vein thrombosis in the leg and pulmonary embolism in the lungs. While some of these blood clots in common location have extremely serious outcomes, a number of cases are less serious than those appearing in overseas TTS reports. These are referred to as 'Tier 2' cases according to the CDC criteria and are defined as only clots found in more usual locations such as the legs or lungs with a low platelet count and a positive test for anti-PF4 antibodies.

Updated reporting rates of TTS in Australia were published in last weeks’ statement from ATAGI. These reporting rates remain consistent with what is being seen internationally, including in Europe, the UK, the Middle East and Canada.

While TTS is very rare, some people will have concerns that they can discuss with their doctor. This is essential to allow people to make an informed choice. Anyone who has been vaccinated should seek immediate medical attention if they develop any of the following symptoms after vaccination:

  • severe or persistent headache or blurred vision
  • shortness of breath, chest pain, leg swelling or persistent abdominal pain
  • unusual skin bruising and/or pinpoint round spots beyond the site of vaccination.

The most common time period for onset of TTS symptoms is 4-30 days after vaccination.

With the ongoing risk of COVID outbreaks in Australia and the potential for severe long-term effects or fatal consequences of infection, the benefits for the AstraZeneca vaccine continue to outweigh the risks.

Up-to-date information about the expected side effects of the AstraZeneca COVID-19 vaccine can be found in the Consumer Medicine Information (for consumers) and Product Information (for health professionals).

Comirnaty (Pfizer) vaccine

Side effects to the Comirnaty vaccine continue to be reported to the TGA and are consistent with what has been observed internationally.

Reports of suspected anaphylaxis following vaccination with the Comirnaty vaccine continue to be rare. People giving vaccines must have medical treatment for anaphylaxis on hand, and must keep people under observation for 15 minutes so that anaphylaxis can be managed, if it happens.

Up-to-date information about Pfizer Comirnaty can be found in the Consumer Medicine Information (for consumers) and Product Information (for health professionals).