My daughter is also moving abroad for 12 months. VHI switched her to its international policy, which provides cover abroad with repatriation to Ireland if she wanted to come home for treatment. The policy also includes travel insurance for trips to other countries while she is away. The policy is not community rated, so the premium depends on factors such as age and health status. In my daughter's case, the premium is less than she was paying for VHI cover in Ireland.
The international policy does not cover any pre-existing medical conditions. VHI also warned that returning to Ireland for treatment mightn't be approved because of the risks involved in travelling during the pandemic.
VHI assured me that she will be able to return to her previous policy when she comes home without having to serve the usual waiting periods.