Omicron concerns see COVID booster interval reduced

Anastasia Tsirtsakis

13/12/2021 3:41:59 PM

The decision to reduce the interval to five months will mean improved protection against the latest variant of concern, ATAGI says.

A calendar with the words ‘booster shot’ marked.
Millions of Australians will become eligible for a COVID-19 booster by the end of the year, after the advisory group fast-tracked the interval from six to five months.

GPs have been given the green light to administer COVID-19 booster shots to all patients over the age 18 at least five months after completion of their primary vaccination course.
The updated guidance means more than 4.1 million Australians will now become eligible for a booster by the end of the year – more than double the expected 1.75 million people had the six-month interval been retained.
The change, flagged on Saturday 11 December, comes amid uncertainty over the Omicron variant and concerns about waning immunity, as Australia prepares to open its borders this week.
The Australian Technical Advisory Group on Immunisation (ATAGI) released its updated guidance on Sunday, recommending people receive either Pfizer or Moderna for their booster, with timely receipt of the third dose particularly important for people who have:

  • increased exposure risk (eg occupational risk or outbreak areas)
  • risk factors for severe disease.
‘As of the 11 December 2021, the weight of evidence suggests that a booster vaccine increases antibody levels substantially and this will likely offer protection against both Delta and the new Omicron variant,’ ATAGI said.
‘The anticipated benefits of bringing forward the booster dose include earlier protection, particularly against severe disease in those at risk, and improved protection against COVID-19 due to the Omicron variant.’
It was just last month that GPs were calling for the advisory group to consider lowering the booster interval, amid concerns that vaccine doses were going to waste as immunisation rates plateaued.
Among them Melbourne GP Dr Joe Garra, who suggested that reducing the interval could be particularly beneficial for healthcare staff who face a higher exposure risk.
But Geelong GP Dr Bernard Shiu is apprehensive about the change.
Despite having previously raised concerns about doses going unused, he says bringing the booster program forward could result in even more wastage.
‘We already have patients educated properly about when to get their booster [and] we changed our computer program to make sure that every patient that has had their second dose from us will get a six-month reminder,’ Dr Shiu told newsGP.
‘So we told them to not come in, do not call us, we will call you when the time comes. What that means is we know exactly how many we need to order because there’s a set date. Now, rolling that a month earlier will mess up the whole program again.’
Meanwhile Dr Shiu said the timing will likely put added pressure on general practice, with many staff already scheduled to take time off over the holiday season, and children aged 5–11 set to become eligible on 10 January.  
‘So who’s going to be able to roll it out only two weeks away from Christmas? It’s going to be chaotic,’ he said.
The change comes just nine days after ATAGI recommended that the interval remain six months for the majority of people, citing that there was ‘no evidence’ to suggest that earlier booster doses would augment protection against the Omicron variant.
However, on Friday, National Cabinet was advised that preliminary reports suggest that the Omicron variant is much more transmissible and has been evading vaccines.
In its latest guidance, the advisory group noted that while there is ‘limited evidence to inform the optimal interval between primary and booster doses’, there are considerable data on the effectiveness and safety of boosters from five months based on Israel’s rollout.
Regardless, Dr Shiu says GPs may struggle to convince patients, and is concerned that yet another change to the rollout may impact patient confidence.
‘We’ve got one report from Israel to say that it’s better [at five months instead of six],’ he said.
‘But we need proper scientific and persistent data to say that, yes, there is a strong reason why we need to roll it out earlier and we need to do it now, instead of waiting.
‘What is clear is [those] who ended up in hospital and ICU are [mostly] the ones that have not been vaccinated at all.’
While much remains unknown about the Omicron variant and its ability to evade vaccine-induced immunity, emerging data suggest immunity after two doses alone may not be adequate.
Federal Health Minister Greg Hunt has said that while two doses will provide ‘very good protection, especially against severe disease’ that the change to the booster program will ensure vaccine protection against COVID-19 is ‘even stronger and longer lasting, and should help prevent spread of the virus’.
‘With over 151 million Pfizer, Novavax and Moderna vaccines already secured for supply into the future, Australia is well prepared to provide booster doses as approvals are provided by the medical experts,’ he said.
Omicron has been detected in more than 50 countries, including Australia since being declared a variant of concern by the World Health Organization (WHO).
For immunocompromised people, ATAGI has reiterated that a third primary dose is recommended a minimum of two months after their second dose, with either Pfizer or Moderna suitable for use.
‘ATAGI is reviewing the timing of a later dose [ie, a post dose three booster dose] in this specific population and will issue advice on this in the near future,’ the advisory group said.
It was in October that ATAGI first recommended boosters for all Australians aged 18 and over from six months after their primary course, or from five months in specific circumstances.
As of 12 December, 89.2% of people over the age of 16 are fully vaccinated and 93.3% have received at least one dose, with more than 40.1 million doses administered. So far, of that cohort, 697,357 have received a third dose, with the figure accounting for both third primary shots and boosters.
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