Photo/Illutration Many car license plates from the Tokyo metropolitan area are seen at a Tsuruya supermarket in Karuizawa, Nagano Prefecture, on March 28. (Hiromu Tsuchiya)

Infectious disease experts warn that residents of the capital who follow the advice of a Twitter hashtag to “Escape Tokyo” risk spreading group infections in their hometowns.

The tag has blown up on Twitter since the government announced on April 6 that it would declare a state of emergency the following day to curb spiking novel coronavirus cases in the capital and other metropolitan areas.

Health authorities have confirmed numerous instances of residents returning to their hometowns to seek sanctuary from the capital's high infection rate only to end up infecting relatives there and others.

A student in her teens returned to her hometown in Shizuoka on March 18. Around the end of the month, four of her family members tested positive for the virus.

She returned to Tokyo on March 24 and was confirmed infected on April 1.

At a hospital in which her mother, a nurse in her 40s, is working, patients and colleagues who had close contacts with her will be subject to polymerase chain reaction virus tests.

A woman in her 30s returned to her hometown in Saga Prefecture from Tokyo at the end of March and experienced virus symptoms during her stay in her grandmother's house.

She tested positive on April 4, as did her mother, who is in her 70s, and her grandmother, who is in her 80s, the next day.

In many cases, medical systems outside the metropolitan areas are strained because of shortages of doctors and hospital beds.

“The medical system will collapse even if a small number of infection cases occur (in some local areas),” warned Dr. Hitoshi Oshitani, a professor at the Department of Virology of the Tohoku University Graduate School of Medicine and a member of a panel advising the government on the coronavirus outbreak, on April 4.

Oshitani posted the comment on a Twitter account operated by experts of the health ministry's cluster task force.

Oshitani said that more people are leaving Tokyo or Osaka, which currently have Japan's highest and second highest number of coronavirus patients.

“We have to avoid actions that could spread the virus as much as possible,” he said.

(This article was written by Kenta Noguchi and Kai Ichino.)