“GAT demands of the Ministry of Health, Directorate-General of Health (DGS), Technical Vaccination Commission and [state medicines agency] Infarmed urgent and exceptional measures to resolve the situation of a lack of vaccines in the quantity necessary to stem this epidemic outbreak," the group said in a statement.

In comments to Lusa, the group's president, Luís Mendão, said that action is needed to prevent fresh outbreaks of hepatitis A in future.

According to Diogo Medina, a GAT doctor, there is only enough doses of the vaccine currently available in Portugal to last until the end of June.

“GAT is warning that Portugal must take measures so that we don't end up in the situation of Spain, which has no vaccines," said Medina, who has been working with the DGS on the hepatitis A epidemic.

The DGS has admitted that there is a shortage worldwide of the vaccine for hepatitis A that is related to bottlenecks in production at the labs that make it. But it has said that Portugal has enough for the current outbreak if the doses are administered on the right criteria.

This week it issued definitions of who should be vaccinated against the disease, in the wake of an outbreak that has already seen 170 people infected this year. These are people who live with or have sexual contact with patients with hepatitis A, as well as men who practise anal sex or oral-anal sex with other men and who live in or travel to and from areas affected by the current outbreak.

People travelling to countries where the disease is endemic are only eligible for the vaccine in exceptional circumstances.

But according to Medina, it is estimated that Portugal needs some 36,000 vaccines a year just for travellers. As for men who have sex with men, some 20,000 doses would be needed to vaccinate all of them