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The vaccine hesitant includes a range of people ranging from people fearful of getting a jab, those fearful of the consequences of getting a jab, to anti-vaxxers.
‘Herd immunity’, also known as ‘population immunity’, is the indirect protection from an infectious disease that happens when a population is immune either through vaccination or immunity developed through previous infection. WHO supports achieving ‘herd immunity’ through vaccination, not by allowing a disease to spread through any segment of the population, as this would result in unnecessary cases and deaths.
See:
https://www.who.int/news-room/q-a-detail/herd-immunity-lockdowns-and-covid-19
For more definitions see:
A large theoretical literature shows how to derive R0 for
different infections, often implying that the 1 – 1/R0
threshold be used as a target for immunization coverage
and that its achievement can lead to eradication of target
infections.
See:
https://www.who.int/news-room/q-a-detail/herd-immunity-lockdowns-and-covid-19
Recent research into New Zealanders’ attitudes to vaccination suggest positions have become more polarised over the last decade, with 60% identifying as “vaccine believers” and 30% as “vaccine sceptics”.
In New Zealand
The overall potential uptake, including those already vaccinated and those who are likely to get a vaccine is estimated to be 79%, from 77% in June, 80% in May and 77% in April. The difference from June is not statistically significant and the result should be regarded as “no change”.
Similarly in the USA A study of more than 1,000 demographically representative participants found that about 22% of Americans self-identify as anti-vaxxers, and tend to embrace the label as a form of social identity.
According to the study by researchers including Texas A&M University School of Public Health assistant professor Timothy Callaghan, 8% of this group “always” self-identify this way, with 14% “sometimes” identifying as part of the anti-vaccine movement.
. . .
“The fact that 22% of Americans at least sometimes identify as anti-vaxxers was much higher than expected and demonstrates the scope of the challenge in vaccinating the population against COVID-19 and other vaccine-preventable diseases,” he says.
See:
Below is a graph showing the percentage of the population that needs to get vaccinated to achieve herd immunity:
This version may be easier to read:
Ro (R0) is the number of people that one person may infect on average in a population where no one is immune.
For the Delta variant of COVID-19 Ro has been estimated between 5 and 8 people.
We have used the same range to estimate Ro for the initial outbreak of COVID-19 in early 2020.
For the Delta variant we have estimated Ro to be between 9 and 12.75.
Regardless, when Ro = 5, from the graph, 80% of a population would need to be vaccinated to achieve herd immunity.
When Ro = 8, the percentage rises to 87.5%.
When Ro =9, we need almost 89% to be immunised.
When Ro =10, we have about 90% and when Ro = 12.75, over 92%.
The graph is created from this table:
Clearly herd immunity is unlikely even when Ro = 8 unless many of the vaccine hesitant get immunised or get a level of immunity when they get infected with COVID-19.
We do not wish anyone to get COVID-19.
At least half of the vaccine hesitant may need to get vaccinated before we get anywhere near a 90% vaccination level in New Zealand.
Do you think a 90% vaccination rate is achievable in NZ?
If you do think 90% is achievable, how soon do you think this may be achieved?
Also see the NZ Herald on Sunday 19 September p6:
Green Bottles, Alan's Ark & COVID Odyssey: Alan Grace's vir[tu]al journey 
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