On January 21, the Strategic Advisory Group of Experts of the World Health Organisation updated its roadmap. The roadmap makes it clear that the highest priority for Covid vaccines is to directly protect people at most risk of severe disease and death from Covid-19.
In New Zealand this is older adults, immunocompromised people of any age, and people with significant health issues, such as heart or lung problems which mean they have lower reserves making them more severely ill from an Omicron infection. Another priority group is people at highest risk of exposure because of working on the front line, such as health workers and border and MIQ staff.
These priorities also apply to booster doses. Immunity after two vaccine doses wanes over time but it is important to understand that this is not the same for everyone.
Older adults and people with compromised immune systems of all ages have lower immune responses which wane faster. At the other end of the spectrum, young people with robust immune systems have higher responses and most had their second dose more recently, so waning immunity is much less of a concern, especially for more severe disease.
New Zealand is in the fortunate situation of having sufficient booster doses available to offer them to everyone 18 years and older from four months after their second dose.
Booster doses are most urgent for people at highest risk, who need to receive them as soon as they are eligible. Providing them with direct protection should be the first priority.
Boosters for lower risk adults and the public health measures in the red traffic light setting also contribute by putting downward pressure on infection and transmission of Omicron.
Before February 2021, New Zealand had no vaccines, only a toolbox of measures to drive down transmission. That toolbox was used well, with New Zealand's Covid death rate of around 10 per million population one of the lowest in the world. A happy consequence of the efforts of the "team of 5 million" with lockdowns was the bonus of reducing other respiratory viruses, particularly flu, contributing to our lower total deaths from overall any cause – the reduction of about 2500 deaths in NZ was more than any other comparable country.
With so few deaths and case numbers compared to other countries, it is understandable we have come to measure success only by counting infection numbers. That will need to change with Omicron as even a continued strong focus on public health measures, mask-wearing, and physical distancing alongside high vaccination will likely still mean much higher numbers of infections than we are used to.
Our new measure of success needs to be keeping the burden on the hospital system and deaths low despite more infections – prioritising boosters for those at highest risk will help achieve that goal.
On January 24, there were still around 21,000 people over 65 and 47,000 between
50 and 64 who had not had their first dose (3 per cent of all over 65s; 1 per cent of Māori but 6 per cent of Pasifika). It is these 68,000 people who are likely to make up most of those filling intensive care units or worse dying, together with a lower but tragic percentage of the 120,000 still unvaccinated 12- to 49-year-olds.
The next most at-risk group are people over 50 years who have had two doses (about 1.6 million) and younger people with significant medical conditions.
For Māori and Pacific people, a younger age for prioritisation should be considered because of their higher risk of respiratory disease.
So, if our primary aim is to prevent severe illness and ensure that the health system can cope with the cases that do occur, what should the priorities be right now?
First, people who are not yet fully vaccinated of any age. We must continue to support our front-line health workers and community groups and reach every individual we can. We now have other vaccine options such as the vector vaccine, Astra Zeneca, for those concerned about mRNA vaccines, and hopefully the protein subunit vaccine from Novavax, approved last week in Australia, will soon be approved here.
Second, go hard on boosters for all, but prioritise older people (over 65 years, followed by 50 to 64 years; over 40 years for Māori and Pacific and adults of any age with significant health problems. Potentially some in these higher risk groups may be under the four months to a booster now and a shortened interval for quicker immediate protection should be considered.
While recognising already heroic efforts at the community and front-line health services level, intensive efforts to actively reach out to older people who are living alone, rural and isolated communities, people with disability, and Māori and Pacific communities will be much less costly and heart-breaking than hospital care if they develop infection.
The "kind community" our Prime Minister refers to, is a community that focuses on our most vulnerable, breaks down access barriers, and walks alongside those with fears, hesitancy, mistrust and feeling marginalised.
High vaccination rates and boosters for those at higher risk, alongside the additional bonus of at least a single vaccine dose for our 5 to 11-year-olds, with the additional layer of protection from the our red-light setting means we can be as world-leading in the post-vaccine world as we have been in the pre-vaccine world.
Let's use our full "Vaccines-Plus" 2022 toolbox in the best possible way.
• Professors Peter McIntyre and Nikki Turner are current and recent members of the Strategic Advisory Group of Experts of the World Health Organisation.