Japan won praise during the COVID-19 pandemic for staying open while other developed economies locked down, which helped lift stocks to three-decade highs. But as the country now struggles with its inoculation program, some investors fear a wave of vaccine envy.

In the past month the Topix has sunk 2.6%. That compared with gains of 7% in the S&P 500 Index and 4.6% by the FTSE 100 in London — where photos of revelers at reopened pubs this week contrast with reports from Tokyo, where hours at bars and restaurants have been shortened as COVID-19 cases surge.

"Japanese indexes are starting to fall behind. Foreign investors are looking at vaccination rates as an investment decision,” said Tomoichiro Kubota, a senior market analyst at Matsui Securities Co. "Markets are at their wits' end right now with the vaccination rate slower in Japan.”