Spain will keep a secret database of people who have refused a coronavirus vaccine and share it with fellow EU countries, according to reports.
Health minister Salvador Illa said the document will not be made public.
He was quoted in The Local as saying: "What will be done is a registry, which will be shared with our European partners... of those people who have been offered it and have simply rejected it.
“It is not a document which will be made public and it will be done with the utmost respect for data protection.”
Vaccinations, however, are not mandatory in Spain.
It comes as the EU’s campaign to vaccinate 450 million people in its member states got off to a difficult start.
In one mishap, eight workers at a care home in Stralsund, Germany, were injected with five times the recommended dose of the Pfizer/BioNTech vaccine. Four were then admitted to hospital.
District chief Stefan Kerth said it happened because of “individual errors”.
In southern Germany, officials had to send back about 1,000 doses after finding they had been transported in cool boxes typically used for picnics. The vaccine needs to be specially stored at a temperature of -70C.
In Italy, meanwhile, some politicians were also alleging Germany, the EU's largest member state and home to BioNTech, may be getting more than its fair share of doses.
In Britain, the first people to get the Pfizer vaccine are due to have their second doses this week.
With the UK the first country to approve the jab earlier this month, grandmother Margaret Keenan had become the first person in the world to receive it.
The 90-year-old had an injection on 8 December, when NHS England said she would have the “booster jab” 21 days later.
On Christmas Eve, five days ago, Boris Johnson said at least 800,000 people had received their first jab.
Since the initial jabs were given in hospitals, the rollout has widened to GP-led sites and care homes.
Meanwhile, the Oxford/AstraZeneca jab is expected to be approved imminently by the Medicines and Healthcare products Regulatory Agency (MHRA).
Compared to the Pfizer/BioNTech jab, this one is easier to transport and store.
NHS England chief executive Sir Simon Stevens said: “We think that, by late spring, with vaccine supplies continuing to come on stream, we will have been able to offer all vulnerable people across this country Covid vaccination.
“That perhaps provides the biggest chink of hope for the year ahead.”
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