The outbreak that could hit New Zealand once our borders open

There's another outbreak threatening the country when New Zealand finally opens up its doors to the rest of the world - and it is also highly contagious.

A leading vaccinologist is warning the risk of New Zealanders catching whooping cough and other respiratory infections once the country's borders reopen could rise due to diminishing immunity to them caused by lockdowns.

Auckland University general practice and primary health care associate professor Dr Helen Petousis-Harris said historical trend data suggested a new outbreak of whooping cough could be imminent within the coming months.

Whooping cough outbreaks occur every four to five years in New Zealand and the last occurred in 2017 and then 2012. During past outbreaks about 600 new cases were recorded each month.

Petousis-Harris said if this trend coincided with the borders opening, then a significant outbreak of whooping cough could hit the country.

"The high level of isolation we've experienced will make us more vulnerable to contracting diseases such as pertussis once they are in circulation as we accumulate susceptible people.

"We saw this with the outbreak of RSV with many not yet having developed or maintained immunity due to a lack of exposure to common respiratory viruses."

A decline in the number of people getting the whooping cough vaccine could also make the problem worse.

Those most at risk from the highly contagious and deadly disease are babies and adults whose immunity from childhood vaccinations has diminished over time and require a booster shot.

Vaccinologist Dr Helen Petousis-Harris is urging people to check they are vaccinated for whooping cough as past trends suggest an outbreak could happen within the next few months. Photo / Supplied

Whooping cough can cause pneumonia, seizures, brain damage and death in babies and rib fractures, weight loss, urinary incontinence and fainting from severe coughing in adults.

Petousis-Harris is leading a project titled The Pertussis Epidemiology in Adults aimed at helping experts better understand the impact of whooping cough, also known as pertussis, in adults.

The study will investigate nationwide infection rates among adults and the impact of the disease across different sub-populations such as age, sex, ethnicity, deprivation, regional distribution and among those with chronic diseases.

Petousis-Harris said this information was vital to better protect people against the whooping cough outbreak. Prior research on whooping cough has focused on children.

She urged people to check their vaccination statuses for whooping cough as it was easy to let them slide during a pandemic.