The Mental Health and Wellbeing Commission chairperson fears people with mental illness and addictions are being left behind in the Covid-19 vaccine rollout.
Ministry of Health figures from January shows people accessing mental health and addition services have full vaccination rates lower than people in the general population.
People that access addiction support services have Covid-19 vaccination rates 19 percent lower than the general population, and mental health service users have rates 9 percent lower than the general population.
For Māori, those figures are lower: addiction service users have Covid-19 vaccination rates 26 percent lower than the general population, and Māori mental health service users have Covid-19 vaccination rates 17 percent lower than the general population.
Commission chair Hayden Wano said that showed some people accessing those services were being left behind in the rollout.
"People who use mental health and addiction services are more likely to be exposed to the virus and, if exposed, are more likely to become seriously unwell," Wano said.
"We know that's partly due to the circumstances people find themselves in, such as poor access to housing suitable housing and a lack of available community support."
The Delta outbreak took hold in more marginalised communities, including people suffering with mental health issues, addictions, and those living in transitional housing.
In mid-December, when the first case of the Omicron variant was reported in managed isolation, figures from data platform Tūtohi showed only 72 percent of people who accessed mental health or addiction services were fully vaccinated against Covid-19.
Wano said the same mistakes could not be repeated and this time around, a community-centred approach was the way forward.
"We cannot speak highly enough about the targeted efforts of Māori and Pacific community providers as well as other service providers and churches, who have contributed to a huge turnaround in rates of vaccination for Māori and Pacific communities," he said.
"This is the kind of targeted approach that is needed to ensure that people who experience mental distress and those who experience addictions have equitable and timely access to the vaccination.
"These groups require active engagement and, in many cases, the best parties to do that are the community-led service providers."
Wano said there were several factors likely behind the lower vaccination rates among people accessing addiction and mental health support services, but he believed it was more likely that access, a level of hesitancy, and lack of trust were the main issues, instead of people being anti-vaccine.
"We know that populations such as Māori and Pacific peoples regularly experience exclusion and racism," Wano said.
"We know that these are factors in their mental health challenges."
Wano said vaccination was a wellbeing issue and if some people found themselves outside the mainstream on vaccination once again, it would further harm their sense of wellbeing.