Calling the shots

The evidence is becoming clearer on the efficacy of a second Covid-19 booster.

- Nicky Pellegrino

For many New Zealanders, it is now around six months since they received their last vaccine to protect against Covid-19. Some may be wondering if it is time for a fourth dose. Conversely, given that numerous people have been infected with Sars-CoV-2 despite being triple-vaccinated, others might be asking if there is any point in being jabbed again.

Much of the research looking at the usefulness of a second booster of the Pfizer Covid-19 vaccine comes from Israel, and the conclusion so far seems to be that it has only marginal benefits if you are young and healthy. There are clearer gains for high-risk people, such as the elderly and severely immunocompromised, and some countries are already offering the vaccine to those groups. In the US, for example, the Food and Drug Administration has authorised a fourth shot for those aged 50 and over as well as the immunocompromised. And in Israel, the groups it has been offered to include healthcare and rest-home workers, adults over 60 and anyone at high risk because of their job.

Most of the world has now recognised that we are living with Covid-19 rather than trying to eliminate it and, as new variants emerge, the focus is on preventing severe disease and hospitalisation. There seems no doubt that the vaccine is playing a key role in this.

“With the Delta variant, receiving two doses was very effective,” explains Dr Nikki Turner of the Immunisation Advisory Centre. “Now, with Omicron, the vaccinations we’ve been using, which match to Delta, are still effective, but the third dose has become a lot more important.”