The 56-year-old woman became a confirmed case on Monday, with genome sequencing showing an exact match to an existing case. The sequencing identified her infection as the highly transmissible South African variant.
The NZ Ministry of Health drew a link between the case and another returnee who stayed at the Pullman Hotel isolation facility in Auckland.
The woman visited a number of places after leaving managed isolation. No other community cases have yet been detected, the country’s Director-General of Health, Ashley Bloomfield, said.
Investigations are ongoing.
Where did she come from and where did she go?
The woman departed New Zealand late last year and travelled through Spain and the Netherlands. While she was in the Netherlands she was in contact with family members who later tested positive for the virus.
She departed London, travelling via Singapore, and arrived in Auckland on December 30.
The woman completed her two-week stint in managed isolation in Auckland and was tested twice – on January 2 and January 10. Both tests returned negative results. She was given the all clear and left the facility on January 13.
There were around 600 guests at the hotel at the same time. Around 13 people tested positive during that time, some with the more virulent strain.
Once she was released into the community, the woman went on a trip around the southern parts of the Northland region on New Zealand’s North Island with her husband.
A total of 30 locations, among them cafes, shops and tourist spots, between Auckland and Whangarei have been identified as linked to her movements – due to her diligent use of the NZ COVID Tracer app – between January 14 and January 22.
She began developing mild symptoms – muscle aches – on January 15. Her symptoms worsened over time. Within days of returning home, her muscles started to ache, but she did not experience respiratory symptoms such as coughing or sneezing.
She was tested on January 22 – around a week after her release from managed isolation – and began self-isolating at home. Her positive test result was returned on Saturday night.
The government is issuing COVID Tracer app notifications to others who may have been in those locations.
Anyone who was at a shared location is considered to have a low risk of exposure, however, the ministry asked these people to self-isolate, contact Healthline, and seek a test.
“If you have any symptoms, get a test promptly,” a message from the ministry read.
Fifteen close contacts have been identified. Two of them, the woman’s husband and her hairdresser, have since returned negative tests.
The woman did not attend mass gatherings and was taking all precautions.
Serology blood testing is taking place to confirm whether the case is new or historical, however, the CT value from the initial test suggests that it is a new infection.
Where did she contract the virus?
Genome sequencing performed on this case was an exact match with another case detected in the Pullman Hotel isolation facility.
The ministry has been able to confidently say the woman contracted the virus within the facility – after her day-12 test, which was negative, and before she was released. This rules out a possible extended incubation period.
The transmission is believed to have occurred between January 9 and January 13, before another guest tested positive on day 3 of their stay. This person has since been classified as recovered and was due for release from quarantine but will stay for a little longer. The extended timeframe for their stay in quarantine hasn’t been released.
How she contracted the virus
This is one of the biggest questions yet to be answered.
The genome sequencing match suggests there was direct contact between the two, with no middle person carrying the infection. But exactly where and when that contact occurred is still being investigated.
There are three possibilities:
She was in proximity to the case and inhaled infected droplets; she touched a shared, contaminated surface where infected droplets had landed; or infected microdroplets – particles too small to be affected by gravity – travelled through the building’s ventilation system.
The ministry was working with the hotel to understand if ventilation transmission was a possibility, and CCTV footage is being reviewed.
The South African strain
The woman has been infected with the South African variant of the virus.
This variant, like the UK variant, is believed to be more transmissible than earlier variants – up to 70 per cent more transmissible – but there’s no evidence to suggest an increase in disease severity or fatality rates.
The variant has the N501Y mutation in the spike protein – the part of the virus that protrudes from the outside, helping to infect cells. This mutation makes the virus latch onto receptors on cells better than earlier variants.