On Wednesday 22 December 2021 ATAGI reviewed the latest developments relating to COVID-19 and COVID-19 vaccine safety. In addition, ATAGI continues to monitor COVID-19 epidemiology in Australia including the Omicron variant of concern and the timing of COVID-19 booster vaccination.
ATAGI stresses that vaccination is a key public health intervention to prevent infection, transmission and severe disease due to SARS-CoV-2. ATAGI recommends COVID-19 vaccination for all Australians from 5 years of age.
ATAGI notes the lower but increasing vaccine coverage in Aboriginal and Torres Strait Islander populations and notes strategies to address barriers to vaccination in this important population.
As at 20 December 2021, over 41 million doses of COVID-19 vaccines have been administered in Australia. ATAGI has noted emerging national data demonstrating that only a small proportion of patients with severe COVID-19 were reported to be vaccinated, consistent with a high vaccine effectiveness against severe disease.
ATAGI notes that the Therapeutic Goods Administration (TGA) has provided provisional registration of the Pfizer COVID-19 vaccine for use in individuals aged 5 to 11 years and recommends is use in this age group.
ATAGI also notes the TGA has provided provisional registration of the Moderna COVID-19 vaccine as a booster dose in adults and as a third primary dose in immunocompromised people.
ATAGI reinforces the benefits of COVID-19 boosters and is currently reviewing the optimal interval between primary COVID-19 vaccination and boosters.
ATAGI recommends either Pfizer or Moderna COVID-19 vaccine as a booster.
Comirnaty (Pfizer) and Spikevax (Moderna)
Myocarditis and/or Pericarditis
ATAGI continues to review and closely monitor reports of rare but potentially serious adverse events following immunisation with Pfizer, including myocarditis and/or pericarditis. These conditions can occur in the absence of vaccination and are also a recognised complication of COVID-19.
ATAGI notes that the TGA is investigating 2745 reports of suspected myocarditis and/or pericarditis following Pfizer and in particular 885 suspected myocarditis reports. Of these suspected cases, 415 cases of myocarditis or myopericarditis have been assessed as meeting the CDC case definition (level 1, 2, or 3), of which 283 cases occurred following the second dose. ATAGI notes the TGA have reported 1 case following a third dose.
ATAGI also notes that the TGA is investigating 75 reported cases of myocarditis following Moderna vaccine, of which 37 have been assessed as meeting the CDC case definition (level 1, 2, or 3). ATAGI are monitoring international data on the rates of myocarditis and pericarditis.
The TGA Weekly Report noted that review by an independent Vaccine Safety Investigation Group on 7 December 2021 found that two fatal cases of myocarditis were not consistent with being caused by based on the available information.
The TGA report detailing the estimated rate of myocarditis following first and second doses by age and sex is published weekly. The observed rates in Australia are consistent with international data. These data show a higher rate in younger individuals (particularly younger males) and following second doses. Most reported cases have been mild, self-limiting and have recovered quickly, although further follow-up of these cases is ongoing. ATAGI noted that a small number of cases were more severe, requiring hospitalisation.
ATAGI has this week again reviewed international data comparing the rates of myocarditis and pericarditis reported after Pfizer and Moderna vaccines. ATAGI notes evidence from several international safety surveillance systems demonstrating that the observed rate of myocarditis is higher, albeit still rare following Moderna compared with Pfizer. The highest observed differences are seen in young males after second doses. There is some evidence to suggest that the risk of myocarditis after second doses of mRNA COVID-19 vaccines may be reduced with a longer interval between primary doses (see below).
There is no evidence to suggest more severe disease with either vaccine.
While data from the US paediatric program (5-11 year old cohort) has not yet been formally reported, early data on the incidence of myocarditis provided by international surveillance networks have not identified concerning safety signals.
