ATAGI recommends shortened interval between AstraZeneca doses during ‘significant’ outbreaks

The Australian Technical Advisory Group on Immunisation (ATAGI) has recommended that the standard 12-week interval between the first and second doses of AstraZeneca be reduced to 4–8 weeks for people located in the worst affected areas.
 
‘People in an outbreak situation who received their first dose of COVID-19 Vaccine AstraZeneca more than four weeks ago should contact their vaccine provider to arrange their second dose as soon as possible,’ the statement reads. 
 
‘In non-outbreak settings, the preferred interval between doses of COVID-19 Vaccine AstraZeneca remains at 12 weeks.’
 
The recommendation follows similar recent calls made by Prime Minister Scott Morrison and NSW Chief Health Officer Dr Kerry Chant, despite evidence of reduced overall efficacy using this regimen.
 
‘A single dose of COVID-19 vaccine AstraZeneca reduces the risk of symptomatic infection by around 30% [95% CI: 24%, 35%] and hospitalisation by 71% [95% CI: 51, 83%],’ the release states.
 
‘However, two doses of COVID-19 vaccine AstraZeneca reduces the risk of symptomatic infection even further, by 67% [95% CI: 61%, 72%], and the risk of hospitalisation by 92% [95% CI: 75, 97%].
 
‘Thus, shortening the gap between first and second doses will bring forward short-term protection, which is expected to be beneficial in outbreak situations.’
 
ATAGI has also updated its stance for people aged under 60 in outbreak zones, and recommended that they re-assess whether or not they should now receive the AstraZeneca vaccine due to ‘changes in the risk–benefit equation’.
 
‘Adults younger than 60 years old [in outbreak areas] who do not have immediate access to COMIRNATY [Pfizer] should re-assess the benefits to them and their contacts from being vaccinated with COVID-19 vaccine AstraZeneca, versus the rare risk of a serious side effect,’ the advisory group’s statement read.
 
‘In outbreak settings, the benefits of COVID-19 vaccine AstraZeneca are increased compared with non-outbreak settings. When the virus is spreading in the community it is critical that as many people as possible are vaccinated as quickly as possible.’
 
Aside from the benefits, the ‘small but significant risk’ following AstraZeneca immunisation is also outlined, in particular the possibility of thrombosis with thrombocytopenia syndrome (TTS).
 
While GPs have been provided with ‘uncertain’ TTS data to help conduct these assessments, ATAGI did provide more detail on the changing risk–benefit equation in areas with a high incidence of COVID-19 cases.
 
‘For context, the current cumulative risk of COVID-19 for residents of Sydney to 11 July 2021 is approximately 10 per 100,000 and is increasing by two additional cases per 100,000 per day,’ the statement reads.
 
‘Although overall this is comparable to the Australian first wave [cumulative incidence 29 per 100,000], the ongoing risk would be considerably greater in some parts of Sydney and for specific populations. For example, in Fairfield Local Government Area, the cumulative risk to date is >100 per 100,000 and has increased by >10 cases per 100,000 per day in the past week.’
 
ATAGI said its original recommendations for non-outbreak circumstances remained the same.
 
Read the full statement.
 
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