Prime Minister Jacinda Ardern receiving her booster dose of the Covid-19 vaccine. Photo: RNZ / Marika Khabazi
For weeks, if not months, New Zealanders have been told the arrival of Omicron in the community was a matter of when, not if.
And as it turned out, Sunday, 23 January was the when.
Aotearoa is now in the red traffic light setting. And the message – from government, opposition, and health officials alike – is clear: one of the key things people can do to help mitigate the worst effects of the Omicron variant is getting a booster shot.
On today’s episode of The Detail, Emile Donovan speaks to immunologist Professor Graham Le Gros and vaccinologist Dr Helen Petousis-Harris about booster shots: what are they? What effect do they have? Is it really that important to get boosted? What does this tell us about the efficacy of the vaccine itself? And is this the new future – a new booster every few months, ad infinitum?
The vaccine “is just prepping your immune system, getting all your immune cells involved”, says Le Gros, director of the Malaghan Institute of Medical Research.
“You put the antigens in, they stimulate the immune system, they trickle along, everything gets activated – and then you starve the immune system.
“Six months, even longer – it’s even better. Only the most potent immune cells for eliminating the virus you’re vaccinating against survive.
“When you give the booster, the only immune cells left are your most elite immune forces – the ones with high-affinity neutralising antibody, the right T cells that see the right determinants. So when you boost, you only activate those.
“They are killers. They will kill the virus very well. And that’s the immunological trick.”
Le Gros says this explains the months-long period in between getting the second dose of the vaccine and the booster: it’s like basic training for the immune cells, and the longer they remain in the body, the better they’ll be.
The ideal period is around six months – or even longer. But Omicron is here now, and because the original vaccine was designed for the original Wuhan variant of Covid-19, it isn’t that effective against Omicron – though undoubtedly it’s much better than nothing at all.
Le Gros says this introduces a tension between having the most efficacious booster possible, and getting as much booster into people’s bodies as possible.
“It’s better to get people boosted because at least you’ll get them immune, and they won’t have as many problems. Because it’s quite clear that it does protect you against Omicron – there’s enough of an effect that you get broad, cross-reactive immunity against Delta, Omicron, etc.”
“Ideally we’d be boosted at six months … but unfortunately, it hasn’t waited … so we’ve got to get on with it and just compromise.”
PIJF Photo: .
