COVID-19 cases are breaking records in parts of Europe as many countries grapple with a new wave of infections.
Four countries, Hungary, the Netherlands, Slovakia and the Czech Republic, all have reported their highest daily COVID-19 infections since the pandemic began, Reuters reported on Wednesday.
Amid the rise in cases, the European Centre for Disease Prevention and Control is recommending booster shots for all adults, reversing its prior stance.
People above the age of 40 will be prioritized to receive the booster.
Around 65 percent of individuals in the European Union are fully vaccinated. That rate is lower - just 54 percent - in the World Health Organization's (WHO) European region, which includes 53 European and Central Asian countries.
Countries in Europe are considering new coronavirus restrictions and vaccine mandates in order to combat the spread of the virus.
Robb Butler, the executive director for WHO Europe, said the organization does not have a position on vaccine mandates to fight the virus. He added, however, that they are a "very delicate" matter.
"It polarizes, you risk marginalizing [people] and it can come at the expense of trust and social inclusion. So it's a very delicate measure, a last-resort measure. Lessons of history have shown us that where vaccines are mandated or made compulsory, there is an erosion of trust and we have seen this polarization," he said.
WHO Europe previously warned the region could see 700,000 COVID-19 deaths in the next couple of months following the spike in cases.