COVID-19 vaccine weekly safety report - 29-07-2021

The most common adverse effects following immunisation reported to the TGA are predictable and have been observed with vaccines generally. They include headache, muscle pain, fever, chills and injection site reactions.

The most common reactions reported for the AstraZeneca COVID-19 vaccine in the week of 19-25 July 2021 were headache, fever, muscle pain, fatigue and nausea.

The most common reactions reported for the Comirnaty (Pfizer) COVID-19 vaccine in the week of 19-25 July 2021 were headache, muscle pain, fatigue, dizziness and nausea.

Interpreting information on vaccine adverse event reports

We are aware that false claims are circulating based on misinterpretation of adverse event information published by the TGA and medicine regulators overseas. To improve transparency, the TGA makes adverse event reports publicly available 90 days after they are received in the Database of Adverse Event Notifications (DAEN).

The TGA encourages reporting of adverse events even if people are uncertain or only suspicious that it is related to a vaccine or medicine or if the event is related temporally, that is following vaccination. This supports our scientists and health professionals to use the data to look for new safety signals. Reporting of adverse events, such as the death of anyone who has received a vaccine, is mandatory for health professionals in some states. It is therefore important to remember that the number of adverse events and deaths is not necessarily an indicator of the safety of the vaccines.

It is important when looking for information about COVID-19 vaccines to consider whether the source of the information is credible. Useful websites such as ‘COVID vaccines – is it true?’ can address false claims and misleading rumours. Other reliable resources are listed at the end of this report.

Latest immunisation recommendations

COVID-19 outbreak

As the COVID-19 outbreak involving the Delta variant continues to grow, the risk of contracting COVID-19 disease remains significant. Emerging data from the NSW outbreak indicates that vaccination protects people from infection and reduces the severity of disease. This is consistent with findings from the original clinical trials.

Although Comirnaty (Pfizer) is preferred over the AstraZeneca vaccine for those aged 16-60 years old, the Australian Technical Advisory Group on Immunisation (ATAGI) advises that in a large outbreak, the benefits of the AstraZeneca vaccine strongly outweigh the risk of rare side effects in all age groups.

It seems that the Delta variant of the virus may cause more severe disease than the original SAR-CoV-2 strain, particularly in younger people. With ongoing constraints of the Comirnaty (Pfizer) vaccine supply, ATAGI recommends that all adults in greater Sydney should consider the benefits of early vaccination with the AstraZeneca vaccine rather than waiting for other vaccines.

Although 2 vaccine doses are needed for maximum protection, a single dose of the AstraZeneca or Comirnaty (Pfizer) vaccine can reduce hospitalisation due to COVID-19 by more than 70%. It appears that a single dose of the AstraZeneca vaccine also reduces the chance of transmission to close contacts by about half. It is important to note however that there is a delay of approximately 2–3 weeks after having a first dose before individuals are protected. 

While there is a higher risk of contracting COVID-19, ATAGI also recommends getting the second AstraZeneca dose within 4–8 weeks after the first dose, rather than waiting 12 weeks, so full protection can be reached sooner. For the Comirnaty (Pfizer) vaccine, the recommended interval between doses is 3–6 weeks.

Vaccination during pregnancy

The Royal Australian and New Zealand College of Obstetricians and Gynaecologists (RANZCOG) and ATAGI recommend immunisation with the Comirnaty (Pfizer) vaccine at all stages of pregnancy. This is due to the risk of complications from COVID disease for pregnant women and their unborn baby. To date, no serious pregnancy-related safety concerns have been identified with the Comirnaty vaccine. Pregnant women are encouraged to discuss the timing of vaccination with their health professional. More details are given on the RANZCOG website.

AstraZeneca COVID-19 vaccine

To 25 July 2021, approximately 6.3 million doses of the AstraZeneca have been administered in Australia. We continue to receive reports of suspected side effects to the vaccine. These are generally consistent with what is being observed internationally and most are expected side effects that resolve within a few days.

Thrombosis with thrombocytopenia syndrome (TTS)

TTS is a rare event involving serious blood clots with a low blood platelet count. It is triggered by the immune system’s response to the AstraZeneca vaccine and is different from other clotting conditions.

The latest rates of TTS in Australia were published in a statement from ATAGI on 21 July 2021.

While TTS is very rare, some people may have concerns that they can discuss with their doctor. ‘Weighing up the potential benefits against risk of harm from COVID-19 Vaccine AstraZeneca’ includes information to help people make informed decisions about vaccination.

Outcomes of 28 July 2021 Vaccine Safety Investigation Group (VSIG) meeting

The TGA convened an expert external Vaccine Safety Investigation Group of clinical experts and consumer representatives to review possible cases of TTS in people who had received the AstraZeneca vaccine. Three were suspected TTS cases after second doses of the vaccine and one was a suspected TTS case after a first dose that was sadly fatal. We extend our sincere condolences to the family and loved ones of this person.

The expert group assessed the available clinical details, diagnostics and pathology results of these cases to determine if they were possibly caused by vaccination.

Death following possible case of TTS

The fatality involved a 54-year-old man from NSW who sadly died approximately 2 months after being vaccinated. The patient had a low platelet count, a clot in the mesenteric vein in his abdomen and evidence of antibodies that activate platelets in the blood (anti-PF4 antibodies). After reviewing the case details and the individual’s medical history, the panel concluded that this was unlikely to be related to vaccination. Coupled with the delay between vaccination and symptom onset, the panel concluded that there were likely to be other causes that sadly led to this man’s death.

Suspected TTS following second doses of AstraZeneca vaccine

Three suspected cases of TTS following a second dose of the AstraZeneca vaccine were evaluated in 2 men and a woman aged between 77 and 81 years old. All of the cases presented with relatively mild symptoms, including common clots in the lungs or leg and mild thrombocytopenia. Importantly, none of the cases had antibodies that activate platelets (PF4 antibodies). In addition, 2 of the individuals had previously had clots, and the other had an underlying condition commonly associated with clots.

Following review of the available information, the panel concluded that all of these cases were unlikely to be related to vaccination.

People who have already received their first AstraZeneca dose should complete the two-dose schedule no confirmed cases of TTS after a second dose have been identified in Australia. Even in the UK, where cases have been recorded, the risk of TTS is extremely low (1.9 cases per million second doses). The TGA is monitoring for Australian cases of suspected TTS after the second dose. We continue to work with our international counterparts to further characterise this syndrome.

TTS cases to date

Since last week’s report, a further 6 reports of blood clots and low blood platelets have been assessed as confirmed or probable TTS likely to be linked to the AstraZeneca vaccine (Table 1).  

‡As previously reported, the TGA determines whether a report is likely to represent TTS by assessing cases against accepted criteria established by the UK’s Medicines and Healthcare products Regulatory Agency.

Two of the probable cases listed above are older cases, but were only classified this week after the TGA received additional clinical information. However, three cases previously reported as ‘probable’ after the second dose have been reclassified as unlikely following advice from the VSIG. This takes the total Australian reports assessed as TTS following the AstraZeneca vaccine to 90 cases (54 confirmed, 36 probable) from approximately 6.3 million vaccine doses. 

When assessed against the criteria used by the US Centers for Disease Control and Prevention (CDC), fewer than half of the cases reported to TGA are classified as Tier 1 cases which tend to have more serious outcomes. Tier 1 cases involve clots in an unusual location, such as the brain or abdomen (Table 2). 

In Australia, severe cases of TTS appear to be more common in women in younger age groups. Nearly half of the TTS cases in women required treatment in intensive care. Cases meeting the criteria for Tier 1 were also twice as likely to occur in women compared to men. Four of the 5 deaths occurred in women aged 48 (2 cases), 52 and 72-years-old. The other death was in a 44-year-old man.  

† The US CDC classification is defined as:

• Tier 1 = clots in an unusual location (such as the brain or abdomen) and a low platelet count with or without antibodies that activate platelets (anti-PF4 antibodies)

• Tier 2 = clots found in common locations (such as the leg or lungs) and a low platelet count and anti-PF4 antibodies

• Not classified = case does not meet the criteria for Tier 1 or Tier 2 (for example clots in common locations with low platelet count but no evidence of anti-PF4 antibodies).

Cases have most often occurred about 2 weeks after vaccination, although the time to onset (or diagnosis) has ranged from one to 54 days (Table 3). 

*Data is based on the most recent medical information available to the TGA

Immune thrombocytopenia (ITP)

The TGA is continuing to monitor reports of suspected ITP, a type of thrombocytopenia or low platelet count. It can occur when the immune system is activated, for example by a viral infection or vaccination, and mistakenly destroys platelets, which help blood to clot. It has been reported with other vaccines and in many cases it is mild with up to a third of people having no symptoms at all, or only minor bruising. However, about 5% develop severe bleeding.

To 25 July 2021, the TGA has received 39 reports of suspected ITP following vaccination. These patients had an extremely low platelet count, and signs of thrombocytopenia including unusual bruising, a nosebleed and/or blood blisters in the mouth. These symptoms occurred in a timeframe that suggested they could be linked to vaccination and no other obvious cause was identified based on the information provided to TGA.

We encourage people to seek medical attention if they experience signs and symptoms that could suggest ITP, such as unusual skin bruising or clusters of small red or purple spots that do not lose their colour when pressed. Unusual bleeding is another sign, for example bleeding from the nose or mouth that is hard to stop, or blood in the urine or stools

Guillain-Barre Syndrome (GBS)

The TGA has been closely monitoring reports of GBS since the beginning of the COVID-19 vaccine rollout as it has been associated with other types of immunisations such as influenza vaccines. So far, international regulators have been unable to either confirm or rule out a possible association between GBS and the vaccine but this continues to be investigated. To 25 July 2021, the TGA has received 63 reports of suspected GBS in people who have received the AstraZeneca vaccine.

GBS is a rare immune disorder in which the body’s immune system attacks nerve cells. What causes it is not fully understood, but it often follows a viral infection (such as influenza, cytomegalovirus and glandular fever) or gastroenteritis caused by a bacteria called Campylobacter jejuni. GBS causes nerve inflammation and can result in pain, numbness, muscle weakness and difficulty walking. In many cases it resolves within months but can sometimes take up to 2 years.

We encourage people to seek medical attention if they experience symptoms that could suggest GBS. This includes weakness and paralysis in the hands or feet that can progress to the chest and face over a few days or weeks.

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

Provisional approval of the Comirnaty vaccine in Australia has recently been extended from individuals aged 16 years and over to include use in children aged 12–15 years old. This decision was made after careful evaluation of data from clinical trials supporting the safety and efficacy of the vaccine in this younger age group.

To 25 July 2021, approximately 4.9 million doses of the Comirnaty (Pfizer) have been administered in Australia. Suspected side effects of the Comirnaty (Pfizer) vaccine continue to be reported to the TGA and are consistent with what has been observed in the clinical trials and by other medicine regulators overseas.

Myocarditis and pericarditis

A causal relationship of myocarditis (inflammation of the heart) and pericarditis (inflammation of the membrane around the heart) to the vaccine is suspected and a warning statement has recently been added to the Consumer Medicine Information and Product Information for the Comirnaty vaccine.

The TGA continues to monitor reports of myocarditis and pericarditis. To 25 July 2021, we have received 84 cases of suspected myocarditis and/or pericarditis.

These rare effects on the heart typically occur within 14 days of vaccination, particularly after the second dose of Comirnaty (Pfizer) and more often in younger men. While cases are usually transient and resolve following rest, some patients require treatment in hospital. We encourage people to seek medical attention if they experience symptoms that could suggest myocarditis or pericarditis such as of chest pain, shortness of breath and palpitations.

We know that myocarditis and pericarditis are much more common with COVID-19 infection and damage to the heart is frequently severe after infection. The benefits of protection against COVID-19 far outweigh the risks from these rare and transient side effects.

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

Useful links

Top 3 COVID-19 vaccine questions – Vaccine wait times, mental health support and vaccine after having COVID-19 – 22 July 2021

Latest ATAGI Statement in response to the NSW COVID-19 outbreak – 24th July 2021

Coronavirus (COVID-19) case numbers and statistics

ATAGI update following weekly COVID-19 meeting – 21 July 2021

COVID-19 vaccines: Frequently asked questions – 15 July 2021

COVID vaccines – is it true? 14 July 2021

TGA COVID-19 vaccines hub

Australian Government Department of Health COVID-19 vaccines hub

AusVaxSafety (active surveillance activities and information) 

COVID-19 vaccine symptom checker

Database of Adverse Event Notifications (DAEN)

Advice on COVID-19 vaccination during pregnancy – 9 June 2021

Comirnaty vaccine – phase III clinical trial

AstraZeneca vaccine – phase III clinical trial