Victoria reduces interval for vaccine doses

Paul Hayes

2/09/2021 4:15:15 PM

Authorities have recommended the time between AstraZeneca doses be reduced to six weeks as the state races to contain a worsening COVID outbreak.

Boxes pf AstraZeneca's COVID vaccine.
The recommended dose interval for AstraZeneca is now six weeks, in line with the recommendation for Pfizer. (Image: AAP)

With the state having conceded it will not be able to drive COVID cases back to zero in the face of the more infectious Delta variant, Victorian authorities have halved the time between doses of AstraZeneca from 12 to six weeks.

This will be implemented at state-run vaccine centres, and the RACGP has been advised that GPs ‘may also choose to use this Astra Zeneca dose interval’.
The change is designed to help Victoria reach higher vaccination targets, which are now the measure for the state to come out of its current lockdown.
‘We are recommending six weeks to get that balance between optimal efficacy and getting as many second doses into people as we possibly can,’ Acting Chief Health Officer Professor Ben Cowie said.
‘That matches the dosage interval for the Pfizer vaccine, so it’ll be six weeks for AstraZeneca and for Pfizer bookings going forward.
‘These changes will be active in the booking system from [Thursday].’
The new advice is in line with Australian Technical Advisory Group on Immunisation (ATAGI) recommendations that the standard 12-week interval between the first and second doses of AstraZeneca be reduced to 4–8 weeks for people in COVID hotspots.
‘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%],’ ATAGI said in its advice.
‘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.’
Professor Cowie said when considering the move to shorten the time between doses ‘the risk–benefit … is clearly in favour of dropping this interval’.
‘It’s why New South Wales have done it, it’s why ATAGI has recommended this, and it’s why our own external advisory group to the vaccination program has recommended this change,’ he said.
NSW residents are able to receive their second AstraZeneca dose four weeks after their first.
Professor Cowie said the new advice applies to people who already have their second dose booked at the 12-week interval.
‘So for people … who need to book in earlier than their allotted 12 weeks, we do have capacity to do that,’ he said. ‘I’d encourage everybody to do that because the sooner we have those people fully vaccinated, the better protected against the Delta variant they are.’
The updated advice came on the same day Victoria recorded 176 COVID cases, the most in its current outbreak and a record for 2021.
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