The inevitable new NZ cases
A top public health doctor says airlines are playing down the risk of in-flight transmission.
A leaked email, from a New Zealand medical officer of health, said it was hard to pin down Covid-19 transmission to what happened in-flight.
‘‘I think that this is part of the reason why there is not a lot of publication.
‘‘Plus the airlines appear to be keen to play down the risk. I understand that a number of Air New Zealand staff have had Covid-19 which, in my mind, suggests likely in-flight transmission,’’ the email, obtained by Stuff, says.
As many as 30 Air New Zealand employees have tested positive for Covid-19.
When contacted by Stuff, the doctor said he didn’t have any special expertise in assessing the risk of transmission on flights, however it depended on how close you were to someone who had the virus, how infectious they were, and the length of the flight.
He said airlines tended to talk about their air filter systems, ignoring the main mode of transmission through respiratory droplets.
Epidemiologist professor Michael Baker said the virus could be spread on a plane, similar to the flu.
Air New Zealand has not made face masks mandatory on flights, although people can bring their own.
Baker said all passengers on public transport should wear masks, with Air New Zealand out of step with best practice for not doing this.
People were at a moderately high risk while boarding and exiting the plane, when air conditioning was off. And it was important people were aware of those conditions, with travel the only way the virus would get in to the country, he added.
An Air New Zealand source has told Stuff passengers boarding international flights were made to stand two metres apart as they queued to board on the air bridge.
But once aboard they could be shoulder-to-shoulder for a long-haul flight.
A spokesperson for Air New Zealand pointed to its website, where it said there is no official requirement for face masks. It was following Government guidance, allowing empty seating between travellers, though this did not rule out families sitting together. For international travel it was providing additional space for travellers ‘‘where possible’’.
‘‘Information provided to us from the International Air Transport Association (IATA) states that based on information they have analysed, the risk of transmission of Covid-19 from one customer to another on board is very low.’’
An E tu¯ union spokesman was not aware of any issues with seating capacity or social distancing rules onboard Air New Zealand.
Crew were directed not to leave the hotels when on layover, he said.
Qantas Group medical director Dr Ian Hosegood said there weren’t any confirmed cases on in-flight transmission.
‘‘Even globally, where thousands of people have flown with Covid, there were only a handful of suspected cases and none confirmed,’’ he said.
Singapore Airlines, which will resume flights to New Zealand on Tuesday, has introduced a number of safety measures, including mandatory face masks on flights.
A Qatar Airways spokeswoman said all passengers must wear face coverings, while cabin crew would wear protective gear.
There is now a 95 per cent chance
Covid-19 has been eliminated in New Zealand, according to our modelling, based on Ministry of Health data.
New Zealand is now preparing to relax its Covid-19 restrictions to alert level 1 from as early as next Wednesday, which would end physical distancing and size restrictions on gatherings. But our modelling suggests removing limits on large gatherings will increase the risk of a very large new outbreak from 3 per cent to 8 per cent.
From the perspective of the virus, the most significant change will be the end of restrictions on the size of gatherings. Airlines can fill up economy class again, nightclubs can pack their dancefloors and universities can open their lecture theatres. Someone who caught the virus three or four weeks ago may not have developed severe symptoms (which happens in around
30 per cent of people) and not got a test. They could have passed the virus on to someone else, who also missed out on a test.
A chain of infections like this could continue for a while before it is detected. Some segments of the population, such as younger people, are less likely to develop symptoms and are therefore more likely to sustain hidden infection chains.
There is also a chance Covid-19 could enter New Zealand with an international traveller. Last week, around 200 people, almost all returning Kiwis, touched down in New Zealand every day.
Between February and April, we know that between 0.1 per cent and 0.2 per cent of all arrivals tested positive. With these numbers, we should expect one or two new cases to arrive each week.
New arrivals must remain in quarantine for at least 14 days. The incubation period for Covid-19 is usually five to six days and it is rare for symptoms to begin more than 14 days after being exposed.
The bigger risk is a symptom-free person arriving and passing the virus onto someone at the same quarantine hotel, who then leaves before their symptoms appear.
Ministry of Health data show eight of New Zealand’s 500 imported cases developed their first symptoms more than two weeks after arriving. Maybe they caught it before they arrived or maybe they caught it during quarantine. Either way, they would have been infectious after they left quarantine.
People who work at the border – airline cabin crew, biosecurity or immigration personnel and staff at quarantine hotels – are at similar risk.
The most important question is how we will cope when the inevitable new case arrives. Each active case is like a small spark waiting to start a fire. To move to level 1, we first need to ensure our contact tracing systems are up to scratch. We need to be confident we can manage the risks when hundreds of people gather or attend protest marches. We have to be able to do these things safely while Covid-19 is still out there.
This article by university researchers was originally published on The Conversation.