With a successful vaccine rollout in their back pocket, Danes essentially returned to pre-pandemic daily life. They visited nightclubs and restaurants without showing a "Covid passport," used public transport without having to wear a mask and met in large numbers without restrictions.

The optimism of mid-September has been short-lived.

Denmark, like many countries across Europe, is now considering whether to reinstate restrictions as the continent battles a surge of Covid-19 cases that has pushed the region back into the epicenter of the pandemic.

Large swathes of Europe are battling to beat back surges of the Delta variant amid the relaxation of restrictions and stuttering vaccine rollouts in some countries, with the WHO warning half a million Europeans could die of Covid-19 in a potentially devastating winter.

In the space of a few months, Europe's Covid-19 fortunes have shifted dramatically. By the end of the summer, many countries had done away with tough restrictions after nations particularly in the west of the bloc charged ahead with vaccination programs and cases plummeted.

Now as other parts of the world reopen, Europe could again be facing a winter of renewed clampdowns.

Repeat restrictions

On Monday the Danish government proposed reintroducing a digital "corona pass" -- used as proof of vaccination or a negative Covid-19 test -- for entering bars and restaurants, as the country faces a third wave of infections, Reuters reported.

The measure will be subject to parliamentary approval. But it comes against the urgent new backdrop of steadily rising cases -- from a low of just over 200 daily infections in mid-September to around 2,300 in recent days.

Denmark is not alone. Austria this week banned unvaccinated people from restaurants and hotels amid a surge in cases. And Iceland reintroduced masks and social-distancing rules following a rise.

Elsewhere, Germany's incidence rate is breaking records on a daily basis. On Tuesday the country recorded its highest seven-day infection rate since the pandemic began, with 213.7 cases per 100,000 people, according to the country's Robert Koch Institute of infectious diseases (RKI).

In some eastern German states, like Saxony and Thuringia, the incident rate has been more than double that, at over 400.

And on Tuesday French President Emmanuel Macron was set to address the nation amid a surge in cases -- his first major TV speech since July when he announced mandatory vaccinations for all health workers.

The United Kingdom has also been battling a stubborn streak of new infections, months after "Freedom Day" celebrations at the end of July marked the removal of almost all Covid-19 restrictions.

Though unlike its European neighbors, the UK has no plans to reinstate restrictions any time soon, including mandatory mask wearing.

Vaccine roll on and on

Denmark's rise in case comes after a successful vaccine rollout, with 88.3% of its adult population fully vaccinated, according to the European Center for Disease Control (ECDC).

On Monday, Health Minister Magnus Heunicke tried to put Denmark's fortunes in the wider context of Europe's ongoing battle with Covid-19.

"Several European countries are now in the middle of their fourth wave of corona," Heunicke said during a televised briefing, Reuters reported. "In Denmark we are heading into our third corona wave."

The European Union as a whole has been a world leader on inoculations, with 75% of adults fully vaccinated, according to the ECDC. But the rollout has been extremely unequal across the bloc; on the eastern side, Romania and Bulgaria have fully vaccinated only 40% and 27% of their adults, respectively.

Now countries are increasingly turning their attention to booster shots in an effort to halt the virus' spread over the winter months, and the prospect of unpopular restrictions over the Christmas period.

Germany and Austria have offered booster shots for everyone six months after receiving their second shot. France has begun administering booster shots to its over-65s, those with underlying health conditions and carers. The United Kingdom, meanwhile has already administered more than 10 million top-up jabs, Prime Minister Boris Johnson tweeted this week.