Epidemiologist Michael Baker is warning pre-departure testing is not enough to keep Covid-19 out of New Zealand communities.
A tougher requirement for pre-departure testing from nearly all countries comes into effect at 11.59pm on January 25. At present travellers from the UK and the US need certified proof of a negative Covid-19 test in the 72 hours before departure.
Baker, a member of the Covid-19 technical advisory group, told Morning Report the overall strategy was excellent but controls need to be increased because the risk had risen, with more of the virus being the very infectious variants.
"We need to do everything we can to turn that tap down over the next few months until we get widespread use of vaccination overseas and hopefully also in New Zealand."
A single pre-departure test a few days before travel is not entirely effective, and people can be incubating an infection while they get the test or become infected afterwards, Baker said.
"One of the options is making people stay or self-quarantine at a hotel at the airport and have an additional rapid test before they get on the flight."
As a last resort, New Zealand could look at suspending travel from hotspot countries which are not pursuing elimination of the virus until a vaccine is widely available, Baker said, but it was better to focus on extra measures for travellers.
Director general of health Ashley Bloomfield told the programme earlier that pre-departure tests were just one part of the prevention measures.
"The core part of our border measures remains that 14 days in managed isolation and the testing that happens there," Bloomfield said.
"What's changed is we've seen these ongoing very high rates of infections in a number of countries from where New Zealanders are returning ... and that includes in particular the UK and the USA, and secondly we've seen the appearance of these more transmissible variants.
"And the third thing is, we have ourselves found [in] our studies evidence of in-flight transmission."
Pre-departure testing was easier to put in place now that virtually all countries have that requirement, he said. "The fact that the airlines are doing that for just about every country makes it much easier to implement and therefore there's real value in adding that to our portfolio."
He said measures inside managed isolation and quarantine facilities were constantly being reviewed to see if there was anything needed to strengthen infection control.