As Japan prepares to expand the scope of its coronavirus vaccine rollout to the entire population, 62.1 percent of people expressed a willingness to receive a shot, a recent online survey by a Tokyo-based medical school has shown.

The poll, conducted in January by a team from Tokyo Medical University, also found that women and younger generations are less accepting of vaccines, underscoring the need for the government to reassure and educate large sections of the populace about their safety.

"In order to raise the level of herd immunity, it is necessary to increase the percentage of those willing to get shots," said Masaki Machida, a research associate at the university's Department of Preventive Medicine and Public Health.

The results were broadly in line with a Kyodo News survey conducted in February, which showed 63.1 percent of respondents in Japan expressing a willingness to get a shot, with women in their 40s and 50s the most wary.

Machida, who led the research released on March 3, explained that there was no major difference between Japan and other countries in coronavirus vaccine acceptance, judging from similar overseas surveys that showed 60 to 80 percent were willing to get inoculated, although it is difficult to make a simple comparison due to different survey methods.

The survey was conducted between Jan. 14 and 18 and received valid responses from 2,956 of 3,000 respondents who were selected by age, gender and where they live to give a representative snapshot of the population.

It was conducted at a time when the number of coronavirus cases was running high, with a record 7,949 daily patients reported nationwide on Jan. 8, prompting Prime Minister Yoshihide Suga to declare a state of emergency, the second of its kind in the country, covering Tokyo and several other high-density regions.

Asked to rate how willing they would be to receive COVID-19 vaccines once available to the public, the proportion of those who replied "very likely" or "somewhat likely" was 62.1 percent.

Drawing on a U.S. survey, Machida said the percentage of vaccination acceptance in Japan may have increased since then as it is probable that worries over safety and side effects have eased somewhat after health care workers started getting jabs last month and shared their experiences through the media and other means.

The U.S. survey found intent to receive COVID-19 vaccine shots increased from 61.9 percent in September to 68.0 percent in December, the same month in which the vaccine rollout started, according to Machida.

The Tokyo Medical University's research showed that vaccine acceptance was lower among several sociodemographic groups. For example, 56.4 percent of women showed a willingness to receive a shot, compared with 68.0 percent of men.

Among age groups, 54.5 percent of people aged 20 to 49 replied they want to get vaccinated, well below the 63.6 percent of those at 50 to 64 years and 74.5 percent of people at 65 and older.

"To increase COVID-19 vaccine coverage in Japan, it may be important to ensure vaccination among these populations with low vaccine acceptance," the report said.

The government is also struggling to increase vaccination rates among younger generations.

Last month, Taro Kono, the minister in charge of vaccination efforts, garnered praise from Machida for sending a video message to the Tokyo Girls Collection, a popular fashion festival for young women, encouraging young people to get vaccinated.