An image has been shared repeatedly in Korean-language social media posts that claim it shows a poster issued by Japan's health ministry warning against receiving a fourth dose of the Covid-19 vaccine due to the risk of decreased immunity. The image has also been shared elsewhere alongside a claim it was issued by the Japan Medical Association (JMA), the country's largest doctors' association. These claims, however, are false. The poster was issued by a voluntary doctors' group in Japan that opposes additional Covid-19 jabs. Japan's health ministry and the JMA both recommend vaccinations for vulnerable groups, and health experts told AFP there is no evidence multiple vaccine doses weaken immunity.
The image of the poster was shared in a Facebook post here on July 17, 2022.
The Korean-language post translates to: "You must never receive a 4th dose!
"The more jabs you receive, the more you will get infected. Not only will there be more positive PCR cases, but the risk of dying will also rise. [The vaccine will] lower immunity. In Japan, the number of people who tested positive for Covid is soaring due to 3rd jabs.
"Vaccines cannot stop infections, nor stop the disease from worsening. You must never get 4th jabs."
Screenshot of the misleading Facebook post, captured on July 20, 2022
However, the poster was not issued by either Japan's health ministry or the JMA.
Poster from anti-booster group
The Japanese-language text in the poster, titled "Opposing fourth jab of the new coronavirus vaccine", does not indicate it has been issued by the country's health ministry.
Instead, the poster questions the ministry's official statistics on infections.
A combined reverse image search and keyword searches on Google found the corresponding poster posted here on the website of the Honbetsu Cardiovascular Medicine Clinic, a local clinic located in the town of Honbetsu in Hokkaido, Japan.
The poster covers two pages.
Below is a screenshot comparison of the poster shared in the misleading Facebook posts (left) and the first page of the poster on the website of the Honbetsu clinic (right):
It is attributed to the Hokkaido Voluntary Doctors' Association -- a local voluntary group -- at the bottom of the second page, which was not circulated in the Korean-language social media posts.
Several of the association's members have also added their names to the poster.
Below is a screenshot of the second page of the poster on the website of the Honbetsu clinic, with the attribution to the Hokkaido Voluntary Doctors' Association highlighted in red by AFP:
The website of the Hokkaido Voluntary Doctors' Association says the organisation "strongly advocates the immediate cessation of all Covid-19 vaccinations from the third dose, for children between the ages of 5 to 11 and for pregnant women."
A joint statement from the group's members posted on the website contains several claims about Covid-19 vaccines, including that they have no proven efficacy for newer Covid-19 variants, and that they can produce various adverse effects in recipients, including blood clots and lowered immunity levels.
Other documents posted on the website also link to the Honbetsu Cardiovascular Medicine Clinic.
'No evidence' boosters weaken immunity
Claims in the poster that booster shots diminish a person's immunity, leaving them susceptible to further Covid-19 infections and possibly death, are not supported by evidence, say medical experts.
"There is no evidence to support this claim," Professor Eom Jung-shik, an infectious disease expert at the Gachon University Gil Medical Center, told AFP on August 3.
"To prove that vaccines weaken your immunity, one must show that after vaccination, either the T cell count diminishes or is weakened, or that antibodies decrease," Eom said.
"But the fact, observed through quantitative and qualitative evidence, is that vaccines increase antibodies and reduce the risk of serious illness."
Professor Kim Woo-joo, an expert in infectious diseases at Korea University, also noted there was "a lack of evidence" to support the idea that multiple doses weaken immunity.
Kim added: "The claim may have gained momentum because Covid-19 vaccines have shown lower efficacy due to the increase in the number of variants, which in turn has produced higher breakthrough infection rates.
"Nonetheless, there is plenty of evidence to show vaccines have saved lives and prevented serious illnesses."
Fourth doses in Japan
Japan's health ministry offers fourth doses of the Covid-19 vaccine for those above the age of 60 and people aged 18 and over who are considered to be at a higher risk from the disease, according to the ministry's official website.
The country will provide fourth jabs between May 25 and September 30, 2022.
The JMA also recommends vaccinations on its website, saying "the spread of infections can be limited if as many people as possible receive vaccinations."
A letter from the organisation issued on July 28, 2022, to regional medical association branches says fourth jabs are recommended for "workers between the ages of 18 to 59 who provide service to people at higher risk of developing severe symptoms at medical facilities, elderly care facilities and facilities for the disabled."