Health officials last night revised the number of suspected cases of swine flu across the country to 43.
Health Minister Tony Ryall said that on the advice of experts - epidemiologists - the risk time-frame had reduced from two weeks to one week.
"New Zealand officials have consulted their expertadvisory group and have changed the relevant period of concern relating to people travelling in Mexico or North America from two weeks to one week," he said.
No one last night was able to say whether any of those 43 had tested positive for Influenza A - the pointer to swine flu - or when those results would be known.
"The key public health message in New Zealand now is anyone who has been in the United States or Mexico in the last seven days, before they may have flu-like symptoms, please contact your general practitioner or health authorities.
"New Zealand considers its status to be 11 confirmed cases and 43 suspect cases."
Director of Public Health Dr Mark Jacobs said: "Obviously we will continue to look out for potential cases of swine flu in returning travellers but the important thing for us to look out for is any significant amount of spread within New Zealand.
"If we start getting cases in people who haven't been out of the country and haven't been, for instance, household members of someone who has come back from overseas, that would be a concern for us and would indicate we needed to escalate our responses."
Meanwhile, quarantine will end for the Rangitoto College students and teachers tomorrow.
They were put into voluntary home isolation for 72 hours after starting a course of Tamiflu medication.
"The bulk of them started on Sunday night," Auckland's top public health official, Dr Julia Peters, said last night.
This meant they could go to school on Thursday, she said.
"The Northcote College group we are releasing from quarantine on Friday morning."
