Nervous about the risk of Covid-19 transmission while on a plane? The flight is all you're likely to catch according to a new transatlantic study by Delta Air Lines.
Using real-world passenger data from almost 10,000 flights between New York-JFK and Atlanta to Rome, the study found the risk of exposure to Covid-19 was less than 0.1% if all passengers tested negative 72 hours before flying.
While the average community infection rate was 1.1% at the time of the study (around one in 100 people), the rate on some Covid tested flights came to 0.05% or one in 2000 passengers.
So, with reports of such low transmission rates on flights, why do many countries, like New Zealand, continue precautionary border approaches and extensive passenger protocols in addition to pre-departure testing?
Why a negative test isn't enough
Similar to the transmission study, almost all passengers travelling to New Zealand must produce a negative Covid-19 test 72 hours before departing.
However, pre-departure tests do not guarantee people will arrive in New Zealand without COVID-19, said an MoH spokesperson.
"Pre-departure testing would not identify anybody who is incubating the disease or who is exposed after they have been tested – either the country they are departing from, transiting through airports and in-flight."
Similarly, Delta Air Line's chief health officer Dr Henry Ting said, while negative pre-departure testing 'significantly mitigates' the risk of Covid-19 exposure and transmission, the use of additional measures in airports and on flights could improve the risk even further.
Dr Ting saying the risk of transmission could be 'less than one in one million' between destinations like the United States and the United Kingdom when procedures such as mandatory masking and hospital-grade air filters were used alongside pre-departure testing.
This is especially important to consider when it comes to New Zealand, where, unlike a non-stop flight from Atlanta to Rome, international flights often require multiple layovers.
So the risk of catching covid from a fellow passenger may be relatively low mid-flight but could be significantly higher, during airport transfers and layovers in the 72-hour test and travel window.
For this reason, the Ministry of Health developed a wide range of requirements to reduce the likelihood of passengers bringing Covid-19 into New Zealand from another country or during a flight.
Informed by advice from Infection Prevention and control experts, WHO and International Air Transport Association, requirements include the use of PPE and face masks for crew and passengers, aircraft air filters, physical distancing, and specific cleaning processes.
These requirements were developed based on advice from Infection Prevention and control experts, and also considered guidance from the WHO and the International Air Transport Association.
Air New Zealand have several measures in place above and beyond these regulations such as the separation of domestic and international staff and replacing masks on long-haul flights every 3-4 hours.