At this point in the National COVID-19 vaccine rollout, Australian Technical Advisory Group on Immunisation (ATAGI) strongly recommends maximising first and second dose vaccine uptake across the community without delay in line with current prioritisation and outbreak response strategies.
Two doses of any of the vaccines available in Australia have been shown to protect an individual from COVID-19 and its complications, as well as protecting the community.
At this time, the Therapeutic Goods Administration (TGA) has not yet received a registration application for the administration of additional doses of any COVID-19 vaccines.
ATAGI is closely monitoring local and international data about the frequency and severity of COVID-19 in fully vaccinated individuals. ATAGI is also reviewing the international data on the efficacy, effectiveness and safety of additional doses for specific high-risk patient populations, including immunocompromised individuals, and the population more generally. These data will inform future strategies regarding additional vaccine doses.
Additional doses can be defined as:
- Third doses: Additional COVID-19 doses required as part of the primary course to reach a comparable (optimal) level of protection
- Booster dose: Additional COVID-19 doses required at a broader population level, to optimise protection due to waning of immunity (loss of protection) over time, with booster doses also leading to improved immune memory.
ATAGI anticipates that a relatively small cohort of individuals, such as those with severely immunocompromising conditions, are likely to require a third dose as part of their primary course of vaccination to ensure optimal vaccine effectiveness. Advice on the need for third doses in this group is anticipated in the next few weeks.
ATAGI anticipates that additional booster doses for other populations may be required in the future. Additional doses are currently being considered but no recommendation has yet been made for the general population at this stage. In addition to the severely immunocompromised, evidence for use in selective cohorts is being actively considered. Detailed advice will be provided as the review progresses. The following points are worth noting in this regard:
- First and second dose coverage in yet to be vaccinated adults and adolescents remains a priority, as high primary COVID-19 vaccine coverage is expected to have the largest impact on protection against severe disease both directly (by direct protection) and indirectly (by prevention of transmission).
- Currently available international data suggests that protection from two doses is maintained against severe COVID-19 disease, including both hospitalisation and intensive care unit (ICU) admissions. This is further supported by the Australian data suggesting that severe COVID-19 following full vaccination is uncommon in the current Delta outbreak.
- The duration of protection provided by additional 'booster' doses is not yet clear. Timing of booster doses to cover anticipated future peaks will be an important consideration.
- Data on the balance of efficacy and safety of third doses of mRNA vaccines is still emerging, so ongoing monitoring of the international experience will be important.
- Consideration is required as to the timing and the type of vaccine to be used as boosters and the potential for newer vaccine types (e.g. protein subunit vaccines [e.g. Novavax], variant vaccines) to become available.
ATAGI is expecting to provide preliminary advice on the need and timing of additional doses in the broader population by the end of October.
ATAGI notes that current procurement arrangements between the Australian Government and vaccine providers are sufficient to provide for first, second and additional doses as required over the next 2 to 3 years.
