Pre-departure Covid-19 tests won't stop new variants entering NZ - virologist

Natalia Sutherland
Source: 1News

Requiring returnees to test negative before boarding a plane to New Zealand won’t prevent people infected with Covid-19, including the new variants of the virus, from coming into the country, a Kiwi virologist says.

Passengers heading to the departure gates at London's Heathrow Airport.

Dr Jemma Geoghegan, a virologist from the University of Otago, says although she agrees with the Government’s new stance on testing prior to departure she doesn’t see it changing current managed isolation and quarantine practices.

“We still need to treat everyone as potentially being infectious or infected that comes into New Zealand,” Geoghegan told 1 NEWS.

“I think perhaps making this a requirement is perhaps quite challenging for a lot of people trying to get home and maybe it’s not really adding anything to our response.”

Yesterday, Minister for Covid-19 Response Chris Hipkins announced returnees from the UK and US would need to return a negative test 72 hours before departure.

Hipkins said the Government is also working to make that a requirement for all countries, except those coming from Australia and some Pacific nations.

Geoghegan says it’s too early to know if pre-departure testing required by the Government would change the number of returnees bringing the virus into New Zealand but says it could be another layer of protection against the virus.

“It’s a good step in limiting some exposure to passengers and cabin crew.”

However, Geoghegan says returning a negative test three days before departure does not mean a person isn’t infected and can become infectious.

“It just means there's not enough virus to be detected at that point in time.

“If you’ve tested negative, it doesn’t mean you’re negative.”

Evidence of transmission in-flight from a person who tested negative for the virus before departure was discovered last year on a flight from Dubai to Auckland.

Geoghegan was part of a research team which discovered “quite clear evidence” of in-flight transmission showing that it’s plausible for people to contract the virus while travelling on a plane.

“What we found was during managed isolation and quarantine that seven people tested positive for SARS-coronavirus had identical or nearly identical genomes so that sparked us to investigate that further.”

Most of the individuals, apart from people in two travel bubbles, didn’t know each other and had flown from different locations until they caught the same flight from Dubai to New Zealand.

“Using genomic sequences, we were able to link all of these cases together and understand their points of contact and it became quite clear there was evidence of in-flight transmission on the way from Dubai to Auckland.”

Geoghegan says long-haul flights such as this where people take off their masks for meals and use shared facilities “really increases the changes of transmission events occurring”.

Yesterday the Government also announcement that they will be extending day zero testing to every returnee.

Testing on the first day could be a useful way to limit transmission in MIQ facilities and catch cases that initially tested negative before flying to New Zealand, Geoghegan says.

Other variants could already be in NZ quarantine

The new UK variant of Covid-19 prompted the Government to change pre-departure rules late last year.

Geoghegan says new variants coming into New Zealand are concerning and they’re monitoring them in MIQ.

“There are new variants evolving all the time because the virus is evolving and we don’t necessarily know all the new variants that may increase the transmission rate that exists in the world because genomic sequencing hasn’t been done for every country for every case.

“It is possible that there are new variants arriving that increases the transmission of the virus from other locations that we don’t know about yet. So, we need to treat every case as highly contagious and do so appropriately.”

To deal with the invisible threat Geoghegan says it’s important to reassess the PPE that is being used in MIQs to make sure it’s up to standard and robust. She doesn’t think, however, New Zealand needs to be taking any extra precautions at its MIQ facilities.

The Ministry of Health says MIQ facilities use appropriate PPE and operate “to an extremely high standard” but will continue to review procedures as new evidence regarding the new strain comes out.