COVID-19 vaccine weekly safety report - 10-06-2021

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 31 May-6 June 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 31 May-6 June 2021 were headache, muscle pain, fatigue, nausea and dizziness.

This week we focus on reports of herpes zoster reactivation (also known as shingles) following COVID-19 vaccination.

Herpes zoster (shingles)

Herpes zoster, or shingles, is caused by reactivation of the varicella zoster virus. The first infection with this virus causes chickenpox, usually in childhood. The virus may then remain inactive in the nerves. If it reactivates, it can cause a painful rash that often occurs as a stripe on one side of the torso.  Risk factors for shingles include older age, a suppressed immune system (caused by a medical condition or treatment), female gender, diabetes, and psychological stress.

Since the beginning of the vaccine rollout to 6 June 2021, the TGA had received 99 reports of herpes zoster following the AstraZeneca vaccine (approximately 3.3 million doses) and 43 reports following Comirnaty (approximately 1.6 million doses). For both vaccines, the majority of these reports were in the 45–64 year age group and 70% were reported in women.

A preliminary review by the TGA indicates that the number of reports of shingles in vaccinated individuals is actually lower than the expected background rate of herpes zoster in Australia overall. Therefore, there does not seem to be a safety signal suggesting that shingles is a result of vaccination. The TGA continues to monitor these cases and investigate whether they are coincidental events or if herpes zoster reactivation could possibly be related to COVID-19 vaccination. Similar reactions have been reported overseas and are being monitored by international regulators. In keeping with the TGA’s conclusion, no international regulators have concluded that vaccination with either the Pfizer or Astra Zeneca vaccine causes shingles.

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 and most are reports of expected side effects that we know occur after vaccination and resolve within a few days.

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. These criteria include:

• evidence of a thrombosis (blood clot)
• thrombocytopenia (blood platelet count below a certain threshold)
• results of blood tests for a specific protein produced by the body to break down clots (D-dimer) and antibodies that activate platelets (anti-PF4 antibodies).

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. One of these cases was in a 52-year-old woman from NSW who sadly died. This case presented as a severe form of this syndrome, with a blood clot in the brain, known as a cerebral venous sinus thrombosis. We extend our sincere condolences to her family. There were also new cases confirmed in a 77-year-old man from NSW and a 70-year-old man from South Australia. The fourth case was in an 87-year-old South Australian woman, which was previously reported as probable but not confirmed at that stage.

In addition, there were four new cases classified as probable in the past week. Three cases were reported in NSW – a 50-year-old woman and two men aged 83 and 91 years. The other case was in a 74-yea-rold female from Victoria.

This takes the total Australian reports of cases assessed as TTS following the AstraZeneca vaccine to 48, with 35 confirmed cases and 13 probable cases. Based on the most recent information available to us:

• 31 have been discharged from hospital and are recovering, with some receiving ongoing outpatient medical care
• 15 patients remain in hospital, including one who remains critically ill in intensive care
• two people have died in hospital.

Updated reporting rates of TTS in Australia were published in last weeks’ statement from ATAGI dated 4 June 2021. 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.

Outcomes of 7 June 2021 Vaccine Safety Investigation Group meeting

The TGA convened an expert external Vaccine Safety Investigation Group of clinical experts and consumer representatives to review two fatalities that occurred shortly after immunisation with the AstraZeneca vaccine. We recognise the devastating impact of these deaths for the families and loved ones involved and extend our sincere condolences.

The expert group reviewed the available medical details of the deaths to determine if they were possibly caused by vaccination or were coincidental.

Death following possible TTS

The first death involved a 55-year-old-man from NSW who sadly died eight days after being vaccinated. The patient had blood clots in his lungs (pulmonary embolism) and evidence from a platelet functional assay suggesting antibodies that activate platelets in the blood (anti-PF4 antibodies). However, the patient did not have thrombocytopenia so did not meet the diagnostic criteria for TTS currently being used by the TGA and globally (outlined above).

The expert group could not conclusively determine if the patient’s death was related to the vaccine, in particular because of the absence of thrombocytopenia. However, it advised that the current criteria for the diagnosis of TTS are likely to evolve as we find out more about this rare condition. If the case definition for TTS changes, this case will be re-evaluated at a later date.

Death following multi-organ failure

The other death considered by the Vaccine Safety Investigation Group was of a 78-year-old man from Western Australia who sadly died from multi-organ failure six days after receiving the AstraZeneca vaccine. The patient had signs of capillary leak, a condition which is often seen in critically ill patients. It is characterised by leakage of fluid from blood vessels into the surrounding tissues and results in swelling and a drop in blood pressure. This has a number of potential causes and can be the endpoint of serious illnesses like sepsis.

We referred this case for expert review because capillary leak syndrome following vaccination has been observed overseas by other regulators. While it has remained under active investigation by the Pharmacovigilance Risk Assessment Committee in Europe, for two months, to date no causal link has been established with the AstraZeneca vaccine.

From the information available, the expert group was unable to establish a link between the vaccine and this patient’s condition as they could not rule out other causes.

We continue to work with international regulators to learn more about the possible relationship between the AstraZeneca vaccine and this syndrome. The TGA will report on this investigation once more information is available.

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.

Myocarditis and pericarditis

Following reports from international regulators in Israel and the US, the TGA continues to investigate suspected myocarditis (inflammation of the heart muscle) and pericarditis (inflammation of the membrane around the heart) reported after vaccination with Comirnaty. To 6 June 2021, nine cases of pericarditis and one case of myocarditis following vaccination have been reported to the TGA. There is no indication at present that these cases are due to the vaccine but the TGA is collaborating with international medicine regulators on this issue.

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

Useful links

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)

The latest from ATAGI – published 4 June 2021

Top 3 questions about COVID-19 vaccines this week – Lockdown and transmission after COVID-19 vaccines, and new COVID-19 strains

The Australian Academy of Science – The AstraZeneca vaccine and TTS