Future of endless Boosters unlikely in Covid battle
As Covid cases soar, Hannah Martin asks what comes next for the vaccine programme in the months and years ahead.
A little over a year ago, New Zealand and much of the world was waiting for a vaccine to spell the beginning of the end of the Covid19 pandemic.
But while the vast majority of Kiwis are now vaccinated, and many have also received their third booster shot as well, we are now facing more cases of Covid than ever before.
Yesterday there were 1901 new cases in the community, and 76 people in hospital with Covid-19.
On Friday there were 1929 cases – the highest number to date.
Yesterday’s cases come from 30,642 tests taken in the previous 24 hours, making the positivity rate 6.2 per cent, the highest it has been so far during the outbreak.
The new cases bring the total number of active community cases to 11,601 those reported in the past three weeks and not yet recovered.
February 20 marks one year since Aotearoa’s vaccination programme began in earnest, rolling out first to border and managed isolation and quarantine (MIQ) workers – though technically the first 25 doses, to vaccinators themselves, were given the day prior.
Authorities were initially hesitant to put a target on vaccination, but in January last year, Director-General of Health Dr Ashley Bloomfield said he hoped at least 70 per cent of Kiwis would be vaccinated.
In the year since, more than 10.1 million doses, including boosters, have been delivered, meaning 96 per cent of eligible people are partially immunised and 95 per cent fully vaccinated.
The roll-out for 5-11-year-olds has seen 47 per cent of eligible children vaccinated in little over a month, and 65 per cent of eligible Kiwis have now been boosted.
However, inequities in access and coverage for minority
groups, particularly Ma¯ ori, have been seen in the adult and paediatric roll-outs; so, too, has a disparity in uptake in urban and rural parts of the country.
A lot has happened in the space of a year. But what about going forward? Will we need boosters forever?
Immunisation Advisory Centre director Dr Nikki Turner thought the ‘‘most likely’’ situation was that many people, particularly young people with healthy immune systems, may need no further boosters.
Just a handful of countries, including Israel, Chile, Cambodia, Denmark and Sweden, are giving a fourth dose, to their most vulnerable populations.
Preliminary data from Israel on people aged over 60 suggested a fourth dose at least four months after a third shot revived antibody levels, doubled resistance against Omicron infection and tripled protection against hospitalisations, compared with only three shots, Nature journal reported.
But that article raised concerns that as protection from boosters might be short-lived, rolling out endless doses, ‘‘potentially at the expense of immunising unvaccinated people in lowincome nations’’, was not a ‘‘viable or long-term global strategy’’.
Vaccinologist Associate Professor Helen Petousis-Harris did not envisage a future of endless boosters.
As the world became increasingly resistant to the virus and its variants, it was more likely going to become a matter of keeping people who were most at risk – such as the elderly – boosted, or targeting the most common variants, she said.
Immunologist Professor Graham Le Gros agreed regular boosting with current vaccines was not the best long-term strategy, noting ‘‘major efforts’’ were under way to develop a vaccine to target all variants.
As the world developed more immunity to Covid-19 – either from disease or vaccination, or both – the need for ongoing boosters lessened, Turner said.
While there was evidence antibody immunity waned over time, people still had cellular memory and protection against severe disease if later exposed, she said.
However, if Sars-CoV-2 mutated in a way that evaded protection offered by current vaccines, a further booster, or multiple further boosters might be needed.
If immunity needed to be boosted more often, we could be looking at a situation like with influenza, where an annual vaccination is given for different circulating strains, she said.
Current vaccines still appeared effective against severe disease from variants coming through, Turner said: ‘‘You’d need a significant variant to see a lot of escape’’.
Hospitalisations, ICU admissions and death rates would be key measures of how well vaccines were working, she said.
If there was a rise in any of those in the coming months or even years, further boosters might be needed.
However, if the disease burden was looking mild, the argument for repeat boosters reduced.
Turner said it was important people understood that getting vaccinated was not now about eliminating Covid-19, it was about protection against severe disease and minimising its impact.
Rolling out endless doses, ‘‘potentially at the expense of . . . lowincome nations’’, is not a ‘‘viable or long-term global strategy’’.