Tonga reported its first confirmed case last month and is experiencing localised community transmission of the Omicron variant.
The bank says its support, which will come from its Asia Pacific Disaster Response Fund, will assist Tonga in meeting immediate response needs and deliver medical services where required.
Meanwhile, New Zealand will contribute US$4 million to support the improvement of water supply and sanitation for Tonga's most vulnerable households.
New Zealand High Commissioner Tiffany Babington said the project would deliver 1500 watertanks and 400 latrines.
The Tonga Government's initial damage assessment of the volcanic eruption and tsunami impacts estimated 468 houses in low lying coastal areas had been destroyed or damaged, with over 300 household water and sanitation facilities damaged.
Therefore, the installation of new water tanks and latrines will enable vulnerable groups to be more adaptive and resilient to climate change, through a community-driven approach where communities participate in needs assessment and design, and shares some cost, to promote local ownership.
"As Polynesian whanau, Aotearoa New Zealand is committed to a deepening partnership with Tonga which supports its resilience, prosperity, stability and security," said Babington.
New Zealand's funding will be earmarked under the Fund for the National Water Tank project and a new sanitation initiative for household latrines.
At the same time, Deputy Prime Minister and Minister of MEIDECC, Poasi Tei said Tonga is grateful to New Zealand for this assistance and acknowledged its timely start.
He said this project will contribute to increasing Tonga's resilience, particularly assisting our vulnerable communities from the adverse impacts of climate change and natural disasters.
"We look forward to our continued partnership and future opportunities to support Tonga through its Climate Change Trust Fund."
The Building Resilient Water Management System project funded under New Zealand's International Development Cooperation Programme will be delivered through the Tonga Climate Change Trust Fund, administered by MEIDECC
A National Water Tank project also managed by MEIDECC in partnership with local communities, aims to install water tanks in over 6,000 households throughout Tonga, targeting the most vulnerable in the community including the elderly, those with disabilities, women and children.