The health ministry is urging COVID-19 patients to be vaccinated twice even after recovering, following the lead of the United States and Canada, which also recommend two shots.
Although some other countries are urging recovered COVID-19 patients to get only one shot, the ministry says that there remains insufficient information to advise reducing the number of vaccinations.
Although COVID-19 patients develop neutralizing antibodies after recovering, much remains unknown, including how long immunity lasts.
An expert committee under the ministry has been discussing whether those who have already been infected need to be vaccinated, using the latest data collected overseas.
One study was conducted on residents in the U.S. state of Kentucky who were infected in May and June 2020, covering 246 people who again tested positive a year later and 492 who did not. It found that of the residents, people who weren't vaccinated were 2.34 times more likely to be reinfected than those who had received shots.
Canada and the United States ask that those who have already been infected with the virus receive two shots in principle. By contrast, Germany and France recommend one shot.
While the World Health Organization and the U.S. say that COVID-19 patients can be vaccinated soon after they recover, Germany asks for a six-month interval after being infected if they have symptoms, while France calls on people to wait at least two months after testing positive.
Considering the varying approaches, the health ministry says that there is not enough scientific evidence to recommend a single shot, as opposed to the usual two doses.
It recommends former COVID-19 patients receive two doses, which can be given just after recovering, in line with the WHO and U.S. advisories.
As for patients who have received antibody "cocktail" treatments to reduce the risk of severe COVID-19 symptoms, the U.S. recommends that they wait at least 90 days after that treatment before being vaccinated, according to Chugai Pharmaceutical Co. Chugai is the maker of Ronapreve, a mixture of the monoclonal antibodies casirivimab and imdevimab, that is currently used in Japan.
Following in the footsteps of the U.S., the health ministry also recommends that people be vaccinated 90 days after receiving that treatment.
For those who don't remember what treatment they received or for people wanting to be vaccinated as soon as possible, the ministry says that they don't have to wait 90 days.
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