Japan has only used about a fifth of the Covid-19 vaccine doses it has imported so far, government data showed, underscoring logistical hurdles such as a shortage of medical staff, as it grapples with a sluggish inoculation campaign.

Japan's unused shots suggest its inoculation push is failing to gain steam, even as inbound vaccine shipments triple over the next two months, Reuters reports.

As imports have started to ramp up, other bottlenecks have become apparent, mainly in manpower. Japanese regulations say only doctors or nurses can administer the injections. The health ministry decided last week that dentists may also deliver shots.