ATAGI recommends Omicron booster

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Eligible people can now receive Moderna’s bivalent vaccine as a top-up.

The Australian Technical Advisory Group on Immunisation has included Moderna’s new Omicron-containing vaccine among the booster options for over-18s.

The bivalent vaccine is not recommended as part of the primary vaccination course (two shots or three for severely immunocompromised people). It contains 50mcg of mRNA, encoding the spike protein from the original SARS-CoV-2 and Omicron BA.1 in equal proportions, whereas primary vaccine doses require 100mcg of mRNA.

The Therapeutic Goods Administration approved the Spikevax Bivalent Original/Omicron BA.1 vaccine for adults on 29 August.

All ATAGI’s other recommendations remain the same:

  • Boosters should be given to people 16 and over at least three months after the primary course or last covid infection
  • Boosters are not recommended for 12-15-year-olds except in the case of complex health needs or immunocompromise
  • A second booster (fourth dose) is recommended only for people who are over 50, in aged or disability residential care, or at risk of severe covid due to chronic illness or multiple comorbidities
  • People 30-49 can receive a fourth dose, but the benefit is less certain.

ATAGI in its statement published yesterday notes that completing a course is more important for ensuring protection than which variant is within the dose.

Only 72% of the eligible population have received their third dose and only 54% of eligible people have received a second booster.

“The Moderna bivalent vaccine generates a modestly higher level of antibody response against multiple SARS-CoV-2 Omicron subvariants (approximately 1.6-1.9 times) including BA.1 and BA.4/BA.5, and a similar antibody response against the original virus, compared with the Moderna original booster vaccine,” ATAGI says.

“There remains uncertainty, however, regarding how this translates to clinical protection. Modelling data suggests that there may be a small increment in protection over an original booster, particularly in those with lower levels of pre-existing immunity.”

ATAGI statement 12 September

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