The European Union on Wednesday urged countries to reinforce their healthcare systems and coordinate restrictions on social gatherings ahead of the Christmas holiday season, to avoid a resurgence of COVID-19 cases.

After a surge of cases in October and November, many European countries have reined in infections by imposing stricter lockdowns and social restrictions.

The European Commission on Wednesday urged governments to keep up measures on physical distancing and mask wearing over the Christmas holidays, and require people to self-isolate before and after social gatherings if rules on meetings are temporarily loosened during the festive season.

This self-quarantine should be for “at least seven” days, the Commission said. Countries should consider banning mass gatherings, while there should be “clear criteria” for small events.

“We know that the sacrifices for keeping each other safe are high. But we cannot allow the risk of seeing Christmas or New Year’s celebrations becoming super-spreading events,” EU Health Commissioner Stella Kyriakides said.

Brussels encouraged countries to use “household bubbles” to limit social contacts if they loosen restrictions during the holidays, and said countries could extend school holidays or impose a period of online learning after the festive season, to act as a buffer against infections.

Hospitals should prepare “surge capacities” in staffing and tap EU programmes to secure protective equipment when needed, the Commission said.

It called on countries to expand testing capacities to track local virus outbreaks, and expand public transport capacity, where possible, to avoid overcrowding. Masks should be mandatory on public transport, the Commission said.

Health policy is a national prerogative in the 27-country bloc and the EU Commission can only make recommendations for common measures.

But by attempting to coordinate countries’ efforts, the EU hopes to avoid a return to the patchwork of different national rules that characterized the first months on the pandemic on the continent.

With the first COVID-19 vaccines potentially available this month, the Commission said it will make recommendations for countries to coordinate the lifting of restrictions once the jab rollout occurs.