This year, for the first time, the vaccines are tetravalent, protecting against four types of viruses, whereas until now they protected against a maximum of three.

This year €11 million was spent on 1.4 million doses for the SNS, whereas last year the investment was €4.3 million for the same number.

The tetravalent vaccine increases the probability that the content of the vaccine coincides with the viruses that will circulate and there is the expectation that the vaccine will be more effective and cover more chances of variation of the flu virus in circulation, the director general of health, Graça Freitas said today.

In addition to the vaccines available to be administered free of charge at the SNS to people at risk (such as the elderly or some chronically ill patients), there will also be more than 600,000 doses in pharmacies, which can be purchased on a doctor's prescription, with a 37% co-payment.

The Directorate-General for Health (DGS) warned that it is impossible to predict the severity of the next flu season and stressed the importance of the country "preparing as well as possible", especially through vaccination.

In addition to the vaccine, it is recommended that chronically ill patients consult their doctor and keep their medication updated, warning that many diseases can be decompensated with the flu, as in the case of diabetes.

In addition, people should take protective measures against the cold and pay attention to the recommendations being given by the health authorities.

The health authority recommends vaccination to health professionals and other care providers, including firefighters, recalling that they are "more likely to be exposed to and to transmit influenza to people at greater risk of complications".

Where it is free and strongly recommended, such as the elderly, nursing home residents and some chronically ill, the vaccine does not require a prescription.