Daily novel coronavirus cases in Tokyo may surpass 1,000 in May if people do not refrain from gathering to celebrate the spring after the current state of emergency is lifted, possibly leading to another contingency, a recent university study found.

The University of Tokyo estimate is based on the assumption that the public frequently meet for cherry-blossom viewing as well as holding farewell and welcome parties around the start of a new business year in April.

The current virus emergency covering the Tokyo metropolitan area is set to expire on March 21 and the study recommended the region ease restrictions in stages to avoid another resurgence.

"We need to lower the number of infections as much as possible during the current emergency," said Taisuke Nakata, associate professor of economics at the university.

"We want (the government) to ease restrictions after lifting the emergency in accordance with the regional situations and take measures such as resuming economic activity in stages," he added.

The computation model developed by Nakata and Daisuke Fujii, a project lecturer at the university, was used to predict the number of infections in Tokyo and how it may impact the economy.

According to the model, the number of daily cases in the capital will fall to around 200 by March 21.

However, infections are expected to rise after the emergency is lifted if all economic activity resumes immediately, with daily numbers projected to surpass 1,000 in May and peak above 1,300 in the third week of that month.

Figures in each of the neighboring Chiba and Saitama prefectures will top 400 and Kanagawa 700, while another state of emergency would become necessary in the metropolitan region.

Meanwhile, peak infection numbers in the capital are expected to stay at around 800 if restrictions are gradually eased over two months. The model predicts cases will continue to decrease once vaccinations for the general public begin, removing the need for a fresh state of emergency and limiting economic repercussions.

Chiba and Saitama prefectures, however, may not be able to avoid another state of emergency even if they ease restrictions over time and may need additional measures to reduce virus cases, according to the study.

If the public refrain from holding too many parties, daily case numbers in Tokyo are expected to hit a peak of around 950 in July even if economic activity resumes immediately after the end of the current virus emergency, it showed.

Under the current virus emergency, Japan's second due to the pandemic, people are asked to refrain from unnecessary outings and restaurants and bars to close early.

The country's vaccination campaign against COVID-19 started in mid-February with front-line health care workers, and people aged 65 or older will start receiving shots in mid-April.

People with pre-existing conditions and those working at elderly care facilities will be targeted next, and then finally the general population, according to the health ministry.

Prime Minister Yoshihide Suga declared a state of emergency for the Tokyo metropolitan area on Jan. 7 before expanding it later that month to a total of 11 prefectures, including Osaka and Aichi.

The emergency now only covers the Tokyo area, with the end date having been pushed back twice for the region as health experts determined a premature exit could lead to a resurgence in infections and put further strains on hospitals.