Study: Vaccines won't prevent 4th wave in Tokyo

A Japanese research team says the ongoing coronavirus vaccine rollout will likely have only limited effects in the coming months in helping curb another possible surge in infections in the capital, Tokyo.

Researchers at the University of Tsukuba used artificial intelligence to estimate how infections in Tokyo will spread after the state of emergency ended on March 21.

They assumed that the rate of increase is the same as last summer, after the first state of emergency was lifted.

The study shows that, without vaccinations, the capital would see a fourth wave peak at 1,850 new cases per day in mid-May.

If Tokyo starts vaccinating about 35,000 elderly citizens, or 0.3 percent of its entire population each day, the daily tally would be 1,650 at its peak in May. That's a dip of only 10.8 percent from the no-vaccination scenario.

If vaccinations are expedited to cover roughly 115,000 people, or 1 percent of Tokyo's population every day, the daily new cases at the peak would be 1,540. That's a 16.8-percent decrease.

The simulation scenarios show that vaccinations are unlikely to prevent a fourth wave.

University of Tsukuba professor Kurahashi Setsuya says vaccinations will not start helping stem infections earlier than July, even if the rollout goes smoothly.

He says it is important to continue basic anti-virus measures, such as preventing droplet infections during group dining.

Healthcare workers across Japan have been receiving the vaccine since last month. Inoculations for elderly citizens will start in April.