Australian Immunization Technical Advisory Group (ATAGI) COVID-19 weekly meeting on October 27, 2021

Date published:

October 29, 2021

Targeted audience:

General public

On Wednesday, October 27, 2021, ATAGI reviewed the latest developments relating to the safety of COVID-19 and COVID-19 vaccines. In addition, ATAGI continues to monitor the epidemiology of COVID-19 in Australia, including current outbreaks of COVID-19 involving the Delta variant, including in New South Wales, the Australian Capital Territory and Victoria.

ATAGI emphasizes that vaccination is a key public health intervention to prevent infection, transmission and serious illnesses due to SARS-CoV-2. ATAGI recommends the COVID-19 vaccination for all Australians from the age of 12.

ATAGI notes the lower but increasing vaccination coverage in Aboriginal and Torres Strait Islander populations and notes strategies to overcome barriers to vaccination in this large population.

As of October 27, 2021, more than 35 million doses of COVID-19 vaccines have been administered in Australia. ATAGI noted the emergence of national data demonstrating that only a small proportion of patients with severe COVID-19 were vaccinated, which corresponds to the high efficacy of the vaccine against the severe disease.

ATAGI has previously noted the registration by the TGA of Pfizer and Moderna for use in children from 12 years of age and supports COVID-19 vaccination in all adolescents from 12 years of age. These statements can be found in the Resources section below. ATAGI also notes the announcement of a booster program using the Pfizer vaccine for those who completed their primary cycle of COVID-19 vaccines 6 months or more ago.

Municipality (Pfizer) and Spikevax (Moderna)

Myocarditis and / or pericarditis

ATAGI continues to review and closely monitor reports of rare but potentially serious adverse events following immunization with Pfizer, including myocarditis and / or pericarditis. These conditions can occur in the absence of vaccination and are also a recognized complication of COVID-19.

ATAGI notes that the TGA is investigating 1375 reports of suspected myocarditis and / or pericarditis following Pfizer and in particular 404 reports of suspected myocarditis. Of these suspected cases, 235 cases of myocarditis or myopericarditis were assessed as meeting the Brighton Collaboration case definition (level 1, 2 or 3), of which 140 cases occurred after the second dose.

ATAGI notes that the TGA report details the estimated rate of myocarditis after the first and second dose by age and sex. The observed rates are consistent with international data showing a higher rate in younger individuals (especially young men) and after the second doses. Most of the reported cases have been mild, resolved spontaneously, and recovered quickly, although further follow-up of these cases is ongoing. ATAGI noted that a small number of cases were more serious, requiring hospitalization.

ATAGI notes that the TGA is investigating 9 reported cases of myocarditis following the Moderna vaccine, 4 of which were assessed as meeting the Brighton Collaboration case definition (level 1, 2 or 3). ATAGI monitors international data on myocarditis and pericarditis rates.

While data on myocarditis after booster doses of Pfizer vaccine are limited, preliminary data from Israel on the use of Comirnaty as a booster dose suggests that the risk of myocarditis with the booster dose is not increased. , compared to the risk after the second vaccine doses.

Risks and Benefits

ATAGI reaffirms that the profits of Comirnaty (Pfizer) and Spikevax (Moderna)

outweigh the risks of myocarditis and / or pericarditis for any age group and strongly recommend that eligible individuals without contraindications be vaccinated.

Vaxzevria (AstraZeneca)

Thrombosis and Thrombocytopenia Syndrome (TTS)

ATAGI reviewed an update from the Therapeutic Goods Administration (TGA) on current confirmed cases of TTS and those under investigation. TGA’s latest statement on TTS cases, including clinical findings, is available here.

ATAGI reviewed estimates of the risk of TTS by age group in Australia and noted that there were 157 confirmed or probable cases of TTS (86 confirmed cases; 71 probable cases). To date, approximately 12.9 million doses of AstraZeneca have been administered.

ATAGI notes that international data continue to show that the risk of TTS after a second dose of AstraZeneca is much lower than the risk after a first dose (internationally estimated at 1.9 per million second doses). ATAGI reinforces the importance of completing a two-dose schedule to ensure maximum protection, with the strongest evidence for two doses of the same brand.

TTS case rates are based on the first doses of AstraZeneca as of October 14, 2021 (to account for time to onset of TTS). To date, approximately 12.5 million doses of AstraZeneca have been administered, including approximately 6.8 million first doses and 5.7 million second doses.

Although risk estimates based on a small number of cases are imprecise, the risk of STT is estimated in Australia to be around:

  • 2.5 per 100,000 among those under 60; and
  • 1.8 per 100,000 in those ≥60 years.

ATAGI notes that the TGA Weekly Report includes a breakdown of current rates by decade of age and a detailed breakdown of confirmed and probable TTS cases in Australia by week using CDC criteria. ATAGI noted that these data suggest that the severity of TTS appears to be higher in younger women. These sex differences are not observed in the elderly.

Results were generally better with early presentation and recognition of symptoms and appropriate treatment, as outlined in the TTS primary care guide. This may contribute to the lower case fatality rate observed in Australia compared to those reported internationally. The overall case fatality rate in Australia (8/157; 5.1%) is lower than reported in other settings. ATAGI notes that TGA continues to investigate 19 probable cases of TTS following second doses and that to date, six of these cases have been definitively linked to vaccination.

Immune thrombocytopenia

ATAGI continues to review and closely monitor reports of rare but potentially serious adverse events following immunization with AstraZeneca, including immune thrombocytopenia (ITP). It is important for people who have been vaccinated to be aware of some of the symptoms that may be associated with ITP, such as bruising and easy bleeding from the nose or gums.

ATAGI notes that following a TGA investigation, the AstraZeneca product information has been updated to include a warning regarding ITP. ATAGI also notes a fatal case that was assessed by a vaccine safety expert group as likely vaccine-related.

Guillain Barre syndrome

ATAGI continues to review and closely monitor reports of rare but potentially serious adverse events following immunization with AstraZeneca, including Guillain-Barré syndrome (GBS). It is important for people who have been vaccinated to be aware of some of the symptoms that may be associated with GBS, such as muscle weakness, unusual sensation (numbness, tingling), and unsteadiness when walking. ATAGI notes that this condition can occur in the absence of vaccination and that investigations to determine whether the reported events are causally related to the vaccination are ongoing.

ATAGI also notes that following rigorous investigations by the TGA and other international drug regulatory bodies, a clear link between GBS and AstraZeneca has not been established. However, as a precautionary measure, warnings regarding GBS have been added to the AstraZeneca product information in response to rare cases following vaccination.

Risks and Benefits

ATAGI reinforces that the benefits of vaccination with AstraZeneca in preventing severe COVID-19 far outweigh the risks of side effects in all Australians ≥60 years of age.

As of October 1, 2021, all Australians aged 12 and over, including Australians aged 60 and over, are now eligible to receive a Pfizer or Moderna COVID-19 vaccine. This means that older Australians can now choose the Pfizer, Moderna or AstraZeneca vaccine.

Anyone can now reserve their Pfizer vaccine through general practitioners and state-run immunization centers, and the Moderna vaccine through pharmacies in individual states and territories.

At this time, there is no update to the ATAGI statement of June 17, 2021 regarding the use of AstraZeneca, except to note that further clarification has been provided regarding its use in epidemic settings.


ATAGI recommends reviewing the following key resources:

Use of AstraZeneca and / or TTS

  • the joint ATAGI / THANZ statement which provides information on TTS and reaffirms previous ATAGI advice regarding the safe use of AstraZeneca;
  • the TTS primary care guide, which provides advice to providers on the examination and management of suspected TTS cases, noting the importance of early presentation and recognition of TTS;
  • the risk-benefit document, which provides guidance to help consumers make informed decisions about the risks and benefits of AstraZeneca in different age cohorts and scenarios; and
  • additional guidance on the use of COVID-19 vaccines in outbreak settings;
  • response to the COVID-19 outbreak in New South Wales; and
  • additional strategies to address the risk posed by the Delta variant of concern.

Use of Pfizer and / or Myocarditis and / or Pericarditis

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