Germany is classifying Spain and the Netherlands as areas with a high incidence of coronavirus, which means that unvaccinated travellers returning from those countries will have to quarantine for at least five days.
The move comes during the summer break from school in Germany, when many families vacation on the sunny Mediterranean beaches of Spain, on or the North Sea coast of the Netherlands.
While nearly half of Germans have had two COVID shots and are therefore exempt from the quarantine rules, only about 2% of under-18s are fully vaccinated, a potential headache for travelling families.
Spain has registered rapid growth in the number of diagnosed cases over the past few weeks. The number jumped five-fold between mid-June and mid-July.
Spain recorded 624 new cases per 100,000 people in the 14 days through the end of last week while the Netherlands had 670 cases, according to the European Centre for Disease Prevention and Control. That compares with 17 in Germany.
The German quarantine requirement for travellers from high incidence regions does not apply to travellers who had COVID-19 in the past six months.
The changes for Spain and the Netherlands take effect from next Tuesday.