Health officials say New Zealand is likely to experience a spike in the number of swine flu cases in the next few months, as pandemic influenza cases increase in the Northern Hemisphere.

World Health Organisation (WHO) reports show high rates of pandemic influenza (H1N1) and influenza-like illnesses in the US, Canada and Mexico. A small increase has been reported in Europe and Northern Asia.

Deputy director of public health Dr Fran McGrath said the MOH expected further clusters of cases over the next few months during the tourist high season, but autumn was the most likely time for a significant upsurge.

A seasonal influenza vaccine will be available in New Zealand in autumn, containing the pandemic influenza strain. People aged 65 years or over and people aged between 6 months and 64 years with a range of chronic conditions will be eligible for a free vaccination.

The latest information, released yesterday, shows the number of swine flu deaths in New Zealand remains at 19, although officials said the number was likely to change as coroners completed investigations into a number of influenza-related deaths over the past few months.

The Ministry of Health said swine flu cases were decreasing, although the illness was still circulating.