Japan seeing more 'breakthrough' COVID cases involving the double-vaccinated


FUKUOKA -- Amid the advancement of Japan's coronavirus vaccinations, more and more reports are emerging of "breakthrough" infections in which people who have received both shots are developing COVID-19.

One such man in the southwestern Japan city of Fukuoka who was infected in August and stayed at a recovery accommodation facility told the Mainichi Shimbun: "I took care even after the second shot. I really didn't think that I would get infected."

The man, who is in his 50s and runs his own business in Fukuoka, started to feel a change in his health around the end of August. He developed a cough, and thought at first that he might have a summer cold, but the next day he developed a fever of 37.8 degrees Celsius. When he took a precautionary PCR test for COVID-19 at a hospital, he discovered he was positive for the coronavirus.

He had received Pfizer vaccines, and his second shot was administered in late July. It's thought that the body produces enough antibodies to fight coronavirus infection within about two weeks of the second dose of vaccination, but by the time the man began showing symptoms he was already over three weeks from his second shot.

In the time between his inoculation and the symptoms showing, Fukuoka Prefecture was placed under quasi-state of emergency measures on Aug. 2, and on Aug. 20 a state of emergency was declared for the prefecture. Amid quickly surging infections, the man continued after his second shot to travel back and forth from his office and work by car, and didn't dine with anyone outside his family. "I really can't think what the route of infection was," he reflected.

After infection, the man, who has an underlying condition, entered a recovery accommodation facility as instructed by the local public health center. His fever lasted for one day, and he returned to a normal temperature after. Because his blood oxygen concentration levels were also normal, he was allowed to leave the facility after 10 days.

He says he's still having light coughs. But among his wife and two children, who were deemed close contacts, one of their unvaccinated kids was confirmed positive. The man said, "I intended to be careful, but maybe somewhere along the line I got complacent from thinking that I've got vaccinated (so I should be safe)."

According to the national government, as of Aug. 31, about 57.37 million people, or 45.1% of Japan's population, have received both shots. Conversely, of the number of people newly infected per 100,000 of the population between Aug. 18 and 20, 88.8 were unvaccinated, 25.2 had their first dose, and 5.4 had both shots. Of the 69,926 people infected in this period, 57,783 people -- 82.6% -- were unvaccinated, 3,351 -- 4.8% -- had their first shots, and 2,625 people -- 3.8% -- had two doses. The inoculation of another 6,167 people -- 8.8% -- was unknown.

Although the risks of infection are greatly reduced by the number of vaccinations had, there does remain a certain risk of "breakthrough" infections. In August at a hospital in the Hokkaido city of Asahikawa, group infections were confirmed among fully vaccinated patients and staff. An older person inoculated twice in Fukuoka died, and people with serious underlying conditions have developed severe cases of COVID-19.

Atsushi Mizoguchi, a professor at Fukuoka Prefecture's Kurume University specializing in immunology, told the Mainichi Shimbun, "Vaccines' effect on preventing infections is very considerable. But when the immune system is compromised due to tiredness or other factors, and if people come into contact with those infected with the delta variant, which carries more virus than previous strains, then exposure to the virus carries a risk of infection. Vaccinated people can't be complacent just because they think symptoms will be mild, because there's always a risk of infecting unvaccinated individuals."

It's been pointed out that antibody quantities do fall with the passage of time following vaccination, and the Japanese government is investigating whether to administer third, "booster" shots to maintain immunity.

Professor Mizoguchi said, "It can't be helped that after vaccination, the passage of time means people are more susceptible to infections, but they do maintain a certain efficacy when it comes to preventing serious symptoms developing. At the same time, people who are older or who have underlying conditions already have weaker immune systems. In the future, to avoid developing serious COVID-19, those people might need to receive a third shot."