“This will overwhelm hospitals,” Grove Krause said. “I don’t have any doubt about it.”

In her office building, where she works with a six-person modeling team, she tried to explain why omicron amounted to such a setback in the fight against the pandemic. She likened the virus to a flood, and described how vaccines, under earlier variants, had acted like two barrier walls safeguarding the health system. One barrier resulted from the vaccines’ ability to reduce the probability of infection, keeping spread low. The other barrier stemmed from the diminished likelihood of severe sickness and death. Both barriers had some holes, but together, they assured the floodwaters never got too high.

But now, she said, the first barrier has been largely removed. Denmark’s data shows people with two doses to be just as vulnerable to omicron infection as the unvaccinated. Those who’ve been boosted have better protection — a sign of hope — but meantime some three of four Danes have yet to receive a third dose, making the majority of the country vulnerable.