Why get a second booster? This is a question many are discussing as the face of the Covid pandemic changes due to new variants of the virus.

The Pfizer vaccine does not work "that well" against the new Omicron BA.5 variant but still offers the best protection, immunologist professor Graham Le Gros says.

A second Covid vaccine booster is recommended by the Ministry of Health for those at increased risk of severe illness from Covid-19 – a minimum of six months after a first booster.

In addition, a second Covid vaccine booster is available for all people aged 50 years and over and health, aged care and disability workers aged 30 years and over. View the full eligibility criteria for second boosters.

Director of the Malaghan Institute and Vaccine Alliance Aotearoa NZ Graham Le Gros says the BA.5 variant has found a "weak link" in people's immune systems, and will probably rise to soon be the dominant virus.

The variant has managed to "shapeshift its spike protein" to be different to spike proteins in previous variants, Le Gros says.

"It's just sneaky... It doesn't seem to be any more deaths but it does seem to be the same level of hospitalisations as the original Omicron, so it's still a very serious virus, it's a variant of concern, it should be taken very seriously - you don't want it, you don't want to be infected by it if you can avoid it."

While the vaccine is not as effective against this strain, it was still the best defence, Le Gros says.

He urges eligible people to get their second booster.

"The virus is still working away from the immunity that's generated by the current Pfizer vaccine, but it's better than nothing and it keeps those levels up - the best protection you have."

Vaccinologists around the world are still working to find a better vaccine, but it was important moves to find a better one are accelerated, Le Gros says.

"There's actually a recent vaccine which came out which works really well against different variants, but you need to be trying to push that forward because we're all sitting back at the moment saying 'we've solved it'. We haven't. This is going to go on and on unless we get a better vaccine."

Le Gros and his team are also working on a pan-Covid-19 variant, which he hopes will be in clinical trials early next year.

Le Gros is hopeful a vaccine will be made which only needs to be given to people once every five years.

"We hope that we can find the sweet spot that really nails this virus. There are a lot of scientists who, the more we learn about it, how it varies, what's important to the virus - it should be possible."

'For those who are not considered at risk of severe illness from Covid-19, a two-dose primary course and a first booster dose provides very good protection against severe illness from Covid-19 at this time,” says a Ministry of Health spokesperson.

People recommended to receive a second booster as a priority are people aged 65 years and over, Māori and Pacific peoples aged 50 years and over, residents of aged care and disability care facilities, and severely immuno-compromised people who received a three-dose primary course and a fourth dose as a first booster - noting this would be a fifth dose for these people.

Other people recommended to receive a second booster as a priority are people aged 16 years and over who have a medical condition that increases the risk of severe breakthrough Covid-19 illness and people aged 16 years and over who live with disability with significant or complex health needs or multiple comorbidities.

See Clinical criteria in support of second booster eligibility

In addition, a second booster is available for all people aged 50 years and over, and health, aged care and disability workers aged 30 years and over.

People can book their Covid-19 vaccine through BookMyVaccine.nz or by calling the COVID-19 Vaccination Healthline on 0800 28 29 26 between 8am and 8pm, seven days a week.

Only Pfizer is approved for use as a second booster.

'After a few months, your protection against the Covid-19 virus starts to drop away, and it's particularly important that you have the booster dose to protect you against this new Omicron variant,” says a Ministry of Health spokesperson.

'Boosters lower your chances of getting very sick from Covid-19 and ending up in hospital.”

People age 16 and over are eligible for Covid-19 vaccine boosters.

'If you've had Covid-19 it's recommended you wait three months after testing positive before getting any Covid-19 vaccination.”

Vaccination rates

Of the eligible population of people aged 12 and over, 95.2 per cent are fully vaccinated, and 73 per cent have had their booster dose of the Covid-19 vaccine, according to Government data.

Vaccines administered to date: 4,028,603 first doses; 3,981,016 second doses; 33,153 third primary doses; 2,714,181 booster doses: 264,399 paediatric first doses and 134,972 paediatric second doses.

According to data from Johns Hopkins University , 549,702,478 cases of Covid-19 were reported worldwide. The total global death toll is over 6,3 million, and more than 11.7m vaccine doses have been administered.

Covid-19 vaccines available in New Zealand

In NZ the Covid-19 vaccines currently available are Pfizer vaccine, Pfizer paediatric, AstraZeneca and Novavax.

These four vaccines have been provisionally approved after a thorough assessment, and must give Medsafe ongoing data and reporting to show that they meet international standards.

Pfizer vaccine is for people aged 12 years or older as a primary vaccination course, and for people aged 18 years or older as a primary course and as a booster.

Pfizer paediatric (child) vaccine is for children aged 5 years to 11-years-old as a primary vaccination course.

AstraZeneca vaccine is for use in people aged 18 years or older as a primary vaccination course or as a booster dose, with a prescription.

Novavax has been approved for primary courses for ages 18 and over. It's a two-dose protein subunit vaccine.

Medsafe has granted provisional approval of Jcovden for primary courses and boosters for ages 18 and over. Provisional approval does not mean Jcovden has been committed for use in New Zealand. Medsafe's provisional approval is the first step, with further consideration required by Cabinet on options for its use. Jcovden is a single-dose viral vector vaccine.

For more information on vaccines available in New Zealand click here

How to get a Covid-19 vaccine booster

You can get a booster dose the same way you got your previous Covid-19 vaccinations – including walk-in sites and drive-throughs.

You can book an appointment for a booster dose through Book My Vaccine or by calling the COVID Vaccination Healthline on 0800 28 29 26 (8am to 8pm, 7 days a week).

Flu vaccine

Free flu shots are now available to all children aged between 3 and 12, as well as anyone with serious mental health and addiction needs. This is in addition to Māori and Pacific people aged 55 and over, anyone else aged 65 and over, pregnant people and those with certain underlying conditions. View full list of conditions.

People can book their flu vaccine at a pharmacy.

Additional reporting by RNZ