Third primary dose and booster vaccines:
- The COVID-19 Vaccine Technical Advisory Group has recommended that individuals aged 12 and older with severe immunocompromise receive a third primary dose of the Pfizer COVID-19 vaccine.
- The third primary dose is optional but recommended.
- There are specific criteria for who can qualify for a third primary dose, this includes individuals who were undergoing immunosuppressive therapies prior to or at the time of their first or second dose.
- Under the current immunisation programme, you cannot receive a booster dose of the Pfizer vaccine in New Zealand unless you qualify under the criteria for a third primary dose.
- The Ministry of Health is reviewing the research as it becomes available and expects to make a decision about booster doses for the general public in the coming months.
Third doses and booster vaccines are different:
An additional, third primary dose is for people who may not have generated an effective protective response to the standard two doses of COVID-19 vaccine due to being severely immunocompromised. These people can now get a third dose as part of their routine vaccination series.
Booster doses are aimed at addressing waning immunity over time. Antibody levels wane for most adults over time, although the level of antibody needed to protect against infection is a lot higher than needed to protect against severe disease if infected. This means that protection against any infection, especially infection with minimal or no symptoms, wanes relatively quickly (within a few months), but protection against severe disease lasts longer, even against the delta variant.
Based on the overseas experience of waning in protection against severe disease, we expect booster shots will be most urgently needed for highly vulnerable people such as the frail elderly or those with significant comorbidities, many of whom will, by November 2021, have had their second dose more than 6 months ago.
The other group for whom boosters need to be considered soon is people with continued occupational exposure to SARS-CoV-2 and/or caring for people with COVID-19 disease, such as health care workers. The rationale for this group is because they are more likely to be exposed to SARS-CoV-2 infection and have a higher potential to transmit infection to people at risk of severe disease.
Boosters are likely to ultimately be needed more widely (eg in the UK being given for all over 50 years), but timing is less urgent, still under discussion in NZ, and will vary depending on risk profile.