Requests by companies for their staff to get COVID-19 vaccinations could become a serious concern when Japan looks to push ahead with booster shots to address increasing cases triggered by the omicron variant, with some firms pressuring even hesitant employees to get inoculated, lawyers say.

Japan's sluggish start to its vaccination program picked up pace from early last summer through inoculation drives at workplaces and large-scale centers while the government started booster shots in early December.

Companies, however, must give careful advice to avoid possible "vaccine harassment," despite feeling a sense of responsibility for their employees' health or clients who may only want to do business with vaccinated people, said Shinobu Yanagita, a lawyer with expertise in workplace harassment.