Severe adverse events
The US Centers for Disease Control and Prevention reported that the Pfizer vaccine has an anaphylaxis rate of 11.1 per 1,000,000 vaccinations.17 Patients who have an anaphylactic reaction to the first Pfizer vaccine dose should not be given a second dose. Patients with a history of anaphylaxis to polyethylene glycol (PEG) preservatives, which are found in medications such as doxorubicin and monoclonal therapies, should not receive the Pfizer vaccine.17,18
Recent independent review of data on the Oxford-AstraZeneca vaccine concluded there was no increased risk of anaphylaxis beyond what is expected with other vaccines.19 There has been one case of transverse myelitis developing within two weeks of vaccine administration.8
A recent question about an increased risk of thrombosis after use of the Oxford-AstraZeneca vaccine has not been supported by vaccine data, and an independent commission to the TGA recommended that the Oxford-AstraZeneca vaccine remains safe for use.20 However, until results of ongoing investigations are available, ATAGI recommends that vaccination with any COVID-19 vaccine should be deferred for people with a history of the rare conditions cerebral venous sinus thrombosis (CVST) or heparin-induced thrombocytopenia.21
Further, several countries have suspended use of the Oxford-AstraZeneca vaccine in people younger than 55 or 60 years because of concerns about a possible link with unusual cases of thrombosis (predominantly CVST) occurring with thrombocytopenia. At the time of writing, Australia has recorded one unusual thrombosis event in 400,000 Oxford-AstraZeneca doses administered.22
ATAGI is meeting regularly and aims to provide clinician and patient advice on the vaccine and thrombosis in early April. As this is a rapidly evolving space, we recommend clinicians regularly check ATAGI statements to healthcare providers regarding thrombosis risk (www.health.gov.au/news/atagi-statement-healthcare-providers-specific-clotting-condition-reported-after-covid-19-vaccination).23
Reporting adverse events
The TGA will continue to monitor vaccine adverse events and encourages reporting from both consumers and health professionals (www.tga.gov.au/reporting-suspected-side-effects-associated-covid-19-vaccine).
Vaccine recommendations for specific populations
All three vaccines were tested on relatively young and healthy populations. Following is a summary of our understanding to date of vaccine efficacy and safety in patients with comorbid medical conditions.
People with medical comorbidities
The COVID-19 vaccines are expected to be safe for patients with stable medical comorbidities. About 10 to 20% of trial patients who received the Pfizer and Oxford-AstraZeneca vaccines had stable comorbidities such as diabetes and pulmonary hypertension. There was no decrease in efficacy or increase in adverse events for patients with these comorbidities.7,8 Data on medical comorbidities and vaccination from the Novavax vaccine trials are yet to be published.