A new COVID-19 subvariant has arrived in New Zealand without a clear link to the border.
Omicron subvariant BA.2.12.1 was found in a case from Hawke's Bay from a test result returned on May 10.
This subvariant has been detected at the border for many weeks, the Ministry of Health said, and there have been 29 imported cases since April.
"Emerging data suggests BA.2.12.1 is marginally more transmissible than the subvariants currently circulating in Aotearoa New Zealand," the Ministry of Health said.
"Our genomic surveillance (genomes and wastewater) remains in place to study any new variants and track their spread."
The ministry added that the public health settings already in place to manage other Omicron variants are appropriate for managing subvariants in the community and no changes are needed.
The BA.2.12.1 is now the dominant form among new COVID-19 cases in the United States, the New York Times reported on Tuesday, making up about 58 percent of all new cases in the country for the week ending May 21.
Emerging data from the World Health Organization also suggests that the new Omicron relatives spread faster than BA.2, one of the first Omicron sublineages.
Despite it spreading faster, US Centers for Disease Control director Dr Rochelle Walensky said that while more research was needed, people who are vaccinated and have had their booster dose have a strong protection against the new variant.
Scientists have found more than 70 Omicron subvariants, according to a database, and two of those - BA.4 and BA.5 - are circulating at low levels in parts of southern Africa and Europe.
These two subvariants have been found in New Zealand in recent wastewater samples taken at Rosedale on Auckland's North Shore and in Gisborne, the Ministry of Health said.
"The presence of these subvariants in the community is also not unexpected," the Ministry of Health said.
"The BA.4 and BA.5 subvariants are being monitored by the World Health Organization; to date, compared to BA.2, there is clinical data to suggest an increased transmissibility but no data suggesting it causes more severe illness."
The vast majority of recently sequenced cases in New Zealand continue to be the Omicron BA.2 subvariant, with a small number of cases the BA.1 subvariant, the ministry added.
"We are continuing to monitor transmission of all variants across the country and internationally. These latest detections emphasise the importance of continued wastewater testing, as increasingly ESR sequencing is able to refine what its testing detects," they said.
"The sequencing can determine that either BA.4 or BA.5 subvariant or both may be present but is not able to be more specific at this stage."
