A decision on who can get a second Covid-19 booster and when will be announced in the “coming weeks”, officials say, as booster uptake appears to have stagnated.

A spokesperson for the Ministry of Health said the ministry was “actively considering” eligibility criteria for the second booster, including how long after the first booster those who were eligible should receive it.

Once this work was complete, the ministry expected to make an announcement on eligibility and timeline in the following weeks, the spokesperson said.

Meanwhile, New Zealand’s booster roll-out appears to have plateaued overall. To date, 2.62 million people have received their booster (70.9% of those eligible), but the dial is barely moving of late.

The recommended course for adult Covid-19 vaccination in New Zealand is three doses for most people (a two-dose primary course, plus a booster) and four doses for those with severe immune suppression (three doses as the primary course, plus a booster).

In March, when Bloomfield first signalled the potential move to introduce a second booster, he said he didn’t anticipate a fourth dose would be required for the wider general population.

Instead, he’d sought advice on a second booster for those at highest risk of severe illness from Covid-19: older people, and those with pre-existing conditions.

He’d also asked whether the offer should be extended to other groups, such as health workers, who received their boosters first, and would therefore have waning (or decreased) immunity.

At the time, Bloomfield said the aim would be to vaccinate eligible groups alongside the flu vaccine roll-out through April and May.

A number of other countries are administering a second booster, mainly to their most vulnerable populations, including Israel, the United States, Cambodia, Chile, Denmark, and Sweden.

In April, research published in the New England Journal of Medicine found a fourth Pfizer Covid-19 vaccine gave triple protection from severe disease among a group of older people in Israel.

The study of more than 1.2 million older Israelis (those 60+) found those given a fourth dose had a 3.5 times lower rate of severe Covid-19 illness than people who’d had three doses.

In the same timeframe, confirmed infection was twice as low compared to three doses.

Pfizer booster doses are available to all those over the age of 16. Those 18+ are eligible to be boosted three months after their second dose, while 16-17-year-olds have to wait six months.

Data back to January 1 shows demand for booster doses peaked in early February, in line with when the majority of Kiwis became eligible and when the Omicron outbreak was starting to gather steam.

This has tapered off over time, and now there are often little more than 1000 booster doses given across the country each day.

Almost a million Kiwis eligible to be boosted have not done so – 988,293 people.

The proportion of eligible Māori (18+ only, not including those 16-17) who have had their booster is 56.4%, and the proportion of Pacific people over 18 is 59.1%.