10 Influenza

10.8 Public health measures

Using influenza signs and symptoms in the diagnosis of influenza is of limited value. The most sensitive diagnostic method is PCR of respiratory nasopharyngeal swabs or aspirate samples.

The methods of controlling influenza are:

10.8.1 Improving vaccine uptake

Studies in New Zealand and overseas have found that provider attitudes and recommendations are key to improving influenza vaccine uptake. Organised registers for recall and opportunistic immunisation are also likely to be important factors in achieving high uptake.

Every effort should be made during March and April to immunise all people at risk, such as those aged 65 years and older, those aged under 65 years (including children) who have certain medical conditions, pregnant women and health care workers. A decision to offer immunisation in winter, during an influenza epidemic, to those who were not immunised in the autumn will depend on the circumstances of the outbreak or epidemic, among other factors. Availability of an appropriate vaccine is the most pertinent of these factors. Vaccination of healthy adults and children is encouraged but is not funded by the Ministry of Health; adult vaccination may be funded by employers.

10.8.2 Antiviral drugsTop

Vaccination of contacts during an outbreak is not immediately effective because of the short incubation period of influenza (one to three days), shorter than the time to mount an immune response following vaccination (up to two weeks). Antiviral drugs are approximately 80 percent effective in reducing influenza symptoms and should be considered for unimmunised or recently immunised contacts at high risk. When used to limit the size of an institutional outbreak, antiviral drugs are usually given for a period of two weeks after immunisation or until one week after the end of the outbreak. Institutional outbreaks should be notified to the local medical officer of health.

10.8.3 PandemicsTop

At the time of a pandemic, the priority groups and the timing of vaccination may be quite different from those during inter-pandemic periods. The New Zealand Influenza Pandemic Plan: A framework for action61 describes the key phases of a pandemic and the actions and responsibilities within each phase.