You had questions about the booster, so we got answers. 

Graham Le Gros, Head of the Malaghan Institute of Medical Research in Wellington, helps us understand what the booster is, why we need it and if we’ll need more in the future.

Why do we need a booster vaccine?

We need a booster because it's the only way to beat Omicron, Graham says.

“Remember, Pfizer was made against the Beta virus. So it's actually designed  for an earlier form of Covid-19. The first two shots got the Alpha, the Beta, and the Delta strains.

“But, Omicron just found a way through with a lot of mutations that change the way it infects.”

Those mutations make the vaccine ineffective against Omicron when you've only had two doses, Graham says. 

“That's the horrible thing. It's about five to ten percent protective. So it does diddly squat to Omicron.However, if you get a booster, we're up at the same 80 to 90 percent level of protection.”

How is the booster different from our first two shots?

The booster is the exact same shot as your first two Covid-19 vaccinations. 

The difference, Graham says, is how your immune system reacts to it.

With the first two shots, your body uses them to figure out the best way to attack the virus. 

That takes a lot of trial and error, with your immune system spending a lot of energy on tactics that have little effect on the virus, Graham says.

After about six months, he says, your body has trained the most elite troops for combatting the virus. 

“When you boost, you only focus on that and you make it very powerful. All the energy of the immune system is put into that very focused part of the immune system.”

How long until it starts giving added protection?

It takes around two weeks.

“So all those people who are taking too long to get their booster shot, get in now because it takes two weeks for the immune system to start winding up and getting those protective antibodies into your bloodstream and into your saliva.”

How does the safety of the booster compare to the double dose?

Because it is the same vaccine, the risks when it comes to getting the booster remain the same as your first two doses, Graham says.

With more than 10 million doses administered, Aotearoa has an adverse reaction rate of 0.5 percent - with headaches, dizziness and lethargy the most common symptoms reported.

Your reaction to the booster is likely to be similar, if not better than your previous vaccinations, Graham says.

“The immune response, that pain and suffering that you go through, is called the innate.”

“It's set at a certain level. That's about as bad as it'll ever get. It never gets worse.”

A serious adverse effect associated with the Pfizer vaccine has been myocarditis, which is an inflammation of the heart. 

There have been 561 reports of myocarditis following Covid-19 vaccinations in Aotearoa.

“Now you've got to remember there's about 250 cases of myocarditis every year without the vaccine. And so you've got this overlay of vaccination on that population,” Graham says.

“If people start to feel palpitations or feel funny, they've got to go and see their doctor. It can be easily treated with simple anti-inflammatory treatments that will make this heart safe.” 

“Don't tough it out or be tough. Go to your doctor if you don't feel well.” 

Why get the booster when Omicron is so mild?

“Omicron is not a mild virus. This virus is very dangerous. It's killed a lot of people already in America and we don't want it to kill New Zealanders,” Graham says.

While Omicron may be less harmful than previous variants of Covid-19, it is far more transmittable.

Which means while an individual has a lesser chance of being hospitalised or dying from Omicron, it still results in many deaths because so many more people are getting infected.

World Health Organisation data showing global Covid-19 cases and deaths up to February 26, 2022. In the first graph, you can see the massive Omicron spike at the end of 2021 caused by Omicron, and the resulting spike in deaths in the same period on the graph below.

Should I get a different type of vaccine for my booster? Like AstraZeneca, if I got a Pfizer?

Early in the booster rollout, there was discussion out of the United States of a mix and match approach to boosters being effective - particularly if you got the Johnson & Johnson vaccine, to have a booster of a different brand.

There are two vaccines available in New Zealand, Pfizer and AstraZeneca.

As more data has come in from the booster rollout, Graham says it’s been found mixing these vaccines and boosters seems to make little difference in the effectiveness of the booster.

A more important deciding factor might be if you had a strong reaction to Pfizer and wanted to try AstraZeneca instead, Graham says.

“There's no problem immunologically [with mixing vaccine types], and you'll get pretty good boosting either way. So there's no worries there.”

I heard the booster doesn’t last long, is it better to wait until Covid is prevalent in my region?

We don’t know exactly how long the booster will be effective, Graham says, because it hasn’t been around long enough to know.

“But it's looking very good so far. And by understanding how the immune system works, I can predict that actually we've got a good year out of this booster shot.”

An ongoing measurement of the effectiveness of a vaccine is to track the levels of antibodies in the blood of those vaccinated. 

From these measurements, Graham is confident that the booster will reduce the rate at which people get really sick or need to be hospitalised for at least a year.

Are we going to have to get lots more boosters?

It is unlikely we will need another booster for the next six months, and likely a year, Graham says.

“There are a number of really good vaccines, being developed both here in New Zealand and around the world, to actually improve the immune response so it actually lasts five to ten years,” Graham says.

“So we won't have to have a booster every year, like some people are worrying about.”

Will this booster help if the virus evolves again?

The booster elevates your immune system to fight at its best against the Covid-19 virus, Graham says, but there is still potential for it to evolve to evade those defences.

However, in the two years of this pandemic, scientists have learnt a lot about the limits of how this virus could evolve and still be harmful, and there is potential for future vaccines to cover all these variants.

“If the virus mutates too much, it can't infect humans anymore,” Graham says. “Like we know the virus can jump into cats and into mice, but then when it tries to reinfect humans it's not as good anymore. So it can't mutate too far away from what it is now.”

“And so we can build a vaccine that covers all the dangerous versions of Covid-19. I'm very confident of that.”

Why is it not available for people under 18? And when will it be?

“Bizarrely, the only reason why is not available for New Zealanders under 18-years-old is because Pfizer have not applied for permission to the New Zealand Medsafe system,” Graham says. “But I'm sure that will come.”

“There's no physiological or biological reason why children cannot get the booster. It's very safe, and a good way of giving long lasting protective immunity against all the different Covid-19 variants.”

The delayed booster rollout for children in Aotearoa has been partly because age groups more vulnerable to the virus have been prioritised, Graham says.

Will the boosters be mandatory?

No vaccine is mandatory in Aotearoa, Graham says.

“Will it become mandatory? Unlikely as it's too severe a kind of personal restriction. However, will it be advised? Yes.”

Will we need a booster to update our vaccine pass?

Currently, the Government Covid website says you do not need to get a booster to be eligible for a My Vaccine Pass or International Travel Vaccination Certificate. 

Your My Vaccine Pass will remain valid even if you do not get a booster dose. 

However, Graham believes boosters should be included in the vaccine pass.

“Only by getting the booster are you safe from Omicron. So, I'm of the opinion that we need to include the booster in our vaccine pass.

“It's Omicron which is the problem. And unless you get the booster, you're not safe from Omicron and you'll spread Omicron throughout the community.”

More stories: 

Covid update March 1: 19,566 community cases, delay in processing 32,000 tests

Eating fish heads for the first time: rangatahi react

The anti-mandate protesters stuck in the South Island