A health expert believes a suspected Omicron case in Palmerston North could have laid dormant for the duration of the person's MIQ stay and five negative tests.

Following the negative tests the person was released from the MIQ facility in Christchurch on Sunday 16 January. They got another Covid-19 test after becoming symptomatic and on Wednesday 19 January received a positive result.

The Health Ministry yesterday said the case who has had two doses of the Pfizer Covid-19 vaccine was considered to be infectious from 17 January and there were multiple exposure events.

The person is now isolating at home and urgent genome sequencing is underway to determine whether they have the Omicron variant as suspected.

University of Canterbury Associate Professor of epidemiology Dr Arindam Basu said Omicron was a peculiar variant so there were a few ways the person could have caught it.

They could have become "reinfected" after an earlier infection, caught it from someone else in MIQ, or their body could have incubated the virus at low enough levels to evade detection, he said.

Health officials said no further positive Covid-19 cases were detected in Palmerston North today.

The MidCentral District Health Board, which covers the greater Manawatū area, said as of 9am today yesterday's case remained the region's sole one.

There were 297 tests processed in the region yesterday, and 216 on Wednesday.

Ninety-three percent of people in the MidCentral region are fully vaccinated.

There are 14 locations of interest in Palmerston North.

People at Cafe 116 in Terrace End from 10.10am to 11.30am on 19 January are considered close contacts of the case and should isolate, test immediately and on day five after exposure. Those at other listed

locations are asked to self-monitor for 10 days and get a test if symptoms develop.

Full list of locations:

• Cafe 116 Terrace End (116 Napier Road, Terrace End) Wednesday 19 January 10.10 am - 11.30am (close contact)
• eSANZ Milson (73 Milson Line) Tuesday 18 January 2.15pm - 2.30pm
• Postie Palmerston North (Shop 1A 210-246 Rangitikei Street) Wednesday 19 January 11.15am - 11.45am
• Bunnings Warehouse Palmerston North (Corner Tremaine Avenue & Railway Road) Monday 17 January 4.54pm - 5.05pm; Tuesday 18 January 10.30am - 10.48am
• Amare Safety Palmerston North (661 Tremaine Avenue) Monday 17 January 3.00 pm - 3.10 pm; Wednesday 19 January 11.45 am - 11.50 am
• Repco Tremaine Ave Palmerston North (915 Tremaine Avenue, Roslyn) Monday 17 January 3.55pm-4.35pm; Tuesday 18 January 10.20am-10.30am; Wednesday 19 January 1.55pm-2.05 pm
• Steelmasters Palmerston North (676 Tremaine Avenue, Papaioea) Monday 17 January 3.10pm - 3.28pm; Wednesday 19 January 11.59am-12.04pm
• Manawatu Locksmith Palmerston North (50A Princess Street) Wednesday 19 January 11.07am-11.12am