Health experts are calling for urgent widespread vaccination to protect the most vulnerable as whooping cough cases in New Zealand hit their highest levels in five years.

The Asthma and Respiratory Foundation NZ, which is supported by leading respiratory specialists, is urging swift preventative measures, particularly for those with existing respiratory conditions.

Figures from the Institute of Environmental Science and Research (ESR) show 187 cases reported in September, more than double the previous month’s total of 75.

Foundation Medical Director Professor Bob Hancox said whooping cough poses serious health risks for people with respiratory conditions.

"Whooping cough is a life-threatening illness for young babies, but can also cause serious illness in those already struggling with respiratory issues.

"It can exacerbate symptoms, leading to hospitalisations or even fatalities."

Even among people without respiratory disease, it can cause a nasty illness with a cough that can last for months, Professor Hancox said.

"So it is crucial that we take this spike in cases seriously - vaccination is our best and strongest defence to protect those who are most vulnerable."

Whooping cough, or Bordetella pertussis, is a highly contagious illness.

According to Healthify, on average, each person with whooping cough passes the infection on to 12 other people.

Whooping cough causes bouts of intense coughing and trouble breathing. Each bout may last for two or three minutes, and the cough can last three months.

It can cause serious illness and sometimes death in babies, young children and older adults.

Foundation Chief Executive Letitia Harding said the best action we can take to protect each other, including the one in five Kiwis affected by respiratory disease, is to get vaccinated.

"As we face the risk of a widespread outbreak, it is critical for at-risk individuals to be vaccinated.

"This includes pregnant people, babies, and older adults with pre-existing respiratory conditions," she said.

"The reality is that whooping cough can be fatal, so we are urging all Kiwis to do their part."