The latest probable case of Covid-19 within the region has tested negative for Covid-19 from the most recent swab.
The Whanganui District Health Board (DHB) said the earlier swab of the case had produced inconclusive results.
A DHB spokesman said the case will still be classed as probable and remain part of the Covid-19 statistics, leaving Whanganui's tally of cases so far at nine probable and confirmed.
The case is being monitored by public health staff and the person is following self-isolation restrictions and does not require hospitalisation.
The case is linked and is in the same household bubble as the eighth confirmed case that was announced on April 19.
Medical officer of health Dr Patrick O'Connor said a lot of work had gone into investigating how the eighth confirmed case, a man in his 20s, had contracted the virus as he was not linked to any overseas travel or to any of the other seven cases.
"There have been no close contacts recently outside the household, and there is no reason to think anyone else has been infected."
He said they have still been unable to establish how Covid-19 came into the household and they may never know.
All of the other seven cases within the region have recovered.
Meanwhile, a pop-up community-based assessment centre (CBAC) will be operating on Friday, April 24, from 10am to 4pm at Te Poho O Tuariki in Marton.
Anyone is welcome and staff will carry out wellbeing checks, screening and swabs and flu vaccinations.
The CBAC is at the site of the former Turakina Māori Girls College at 85 Hendersons Line.
Whanganui's Emergency Operations Centre says there are several ways for people to get welfare support if they need it.
Those with existing support networks should continue to use them but there is additional support available from welfare teams if needed.