Japan is no longer the best-performing wealthy nation when it comes to avoiding COVID-19 deaths.

The country, which has one of the oldest populations in the world, is quietly experiencing its biggest outbreak of the pandemic. A wave of omicron infections overwhelmed its health system this winter and delayed medical care for patients, sending daily deaths to a record high of more than 500 on Jan. 14, according to data compiled by Bloomberg.

The increase pushed Japan*s overall mortality rate above New Zealand*s, which now has the fewest deaths per capita among the OECD*s 38-member countries, according to Our World in Data. Infection rates in Japan, while still among the lowest in the world, rose rapidly in recent months.