A history of vaccine controversies in Japan may cast a long shadow over the coronavirus jab roll-out, experts warn, even as the country battles a severe third wave of infections.
While vaccine hesitancy, and outright opposition, has been growing in developed countries in recent years, public suspicion dates back much further in Japan.
Even as millions in the UK and US are being inoculated against Covid-19, Japan has yet to approve a single jab, and vaccinations will not start before late February at the earliest.
This week, Prime Minister Yoshihide Suga said he would be among the first to be vaccinated, in an apparent attempt to bolster lukewarm confidence about the jab.
Just 60 percent of Japanese respondents in a December Ipsos-World Economic Forum survey said they want the vaccine, compared with 80 percent in China, 77 percent in the UK, 75 percent in South Korea and 69 percent in the US.
The figure was still significantly higher than the 40 percent recorded in France.
Another poll, by Japanese broadcaster NHK, showed just half of respondents want the vaccine, with 36 percent opposed.
Mistrust in Japan dates back decades, with experts pointing to a vicious cycle of lawsuits over alleged adverse events, media misinformation and government overreaction.
"The reason why Japanese are hesitant, I think, is because there is a lack of trust in government information," Harumi Gomi, professor at the Center for Infectious Diseases at the International University of Health and Welfare, told AFP.
- Loss of confidence -
As early as the 1970s, class action lawsuits were filed against the Japanese government over side effects linked to smallpox and other vaccines.
And two deaths that followed vaccination with the combined diphtheria, whooping cough and tetanus shot prompted the government to temporarily withdraw the jab.
It was reintroduced shortly after with new rules but confidence did not recover.
Then in the late 1980s and early 1990s, cases of aseptic meningitis among children who received locally produced combined measles, mumps and rubella vaccines caused renewed outcry, prompting withdrawal of the combined jab.
A key turning point was a 1992 court ruling that held the government liable for adverse reactions to several vaccines, including side effects -- even without scientific evidence of a link.
"Following the lawsuits, I think the government must have thought they would be sued if they actively introduced vaccines and there was a problem," said Tetsuo Nakayama, a project professor at the Kitasato Institute for Life Sciences who focuses on clinical virology.
"People thought something (negative) might happen if they get vaccines," he added.
"As a result, Japan's vaccine programmes did not advance for 15 to 20 years."
There has been grassroots work by doctors to build trust, with some success, notably with the Hib vaccine, given to young children to prevent an infection that can otherwise lead to meningitis.
"Hib vaccines became available in 2008 thanks to efforts by pediatricians," Nakayama said, adding Japan's vaccine programme "began to change course then".
But there was another setback soon after, with massive media attention on adverse reactions allegedly tied to the human papillomavirus (HPV) vaccine.
Despite scientific doubt about the links, the outcry prompted the government to remove the vaccine from its list of actively recommended shots.
- 'Proper risk communication' -
Subsequent investigations have found no cause for concern, and the HPV vaccine is widely administered elsewhere.
But in Japan, uptake has plummeted from 70 percent to less than one percent, according to an article in the Lancet medical journal.
"This is a very disappointing situation to me as a specialist," Gomi said.
For now, Japan is weeks, if not months, from any large-scale roll-out of a coronavirus vaccine, which will be provided for free.
It has secured sufficient doses for all 127 million residents in deals with Moderna, AstraZeneca and Pfizer, which filed for approval of its jab in December.
A decision on that is unlikely before February, and Nakayama said the government should work to build trust before then through "proper risk communication with the public".
"They need to explain the risks when infected with the virus, the benefits of vaccines and their side effects," he said.
Gomi, who is treating virus patients, said vaccine uptake would depend on clear explanations by healthcare workers and responsible media coverage.
"No vaccine is 100 percent safe. Vaccine programmes won't work if that's what people want," she said.