Government officials and scientists are moving to update countermeasures for a possible influenza pandemic after this winter’s global spread of avian flu.

Researchers plan to review the government’s death toll estimate from a possible flu pandemic that was drawn up more than a decade ago and no longer reflects the nation’s latest medical situation.

“We need to conduct a comprehensive review of measures in light of changes to the situation,” said Nobuhiko Okabe, who chairs a health ministry subcommittee on new strains of flu.

The highly pathogenic H5N6 strain, first detected in November among poultry farm birds, has since spread across Japan.

There had been more than 200 cases of avian flu infections confirmed among wild birds as of early February. Infections at poultry farms led to mass cullings by local authorities.

Yoshihiro Kawaoka, a professor of virology from the Institute of Medical Science at the University of Tokyo, says measures were taken “very swiftly” at the farms.

A quick response is considered important to prevent the virus spreading to other animals or humans and of to stop it transforming into a type more likely to cause a pandemic.

Governments across the globe have begun to step up measures after the H5N1 bird flu strain killed six people in Hong Kong in 1997.

As the virus claimed more victims following the initial deaths, world governments began to adopt more robust measures to prevent the disease from developing into a pandemic.

Japan created its first action plan in 2005, basing its estimate on a U.S. model that up to 640,000 people could die from the disease.

In line with the action plan, Japan has stockpiled vaccines against the H5N1 strain.

A global pandemic occurred in 2009, however, of the anticipated H5N1 strain as well as so-called swine flu from an H1N1 strain. As this strain did not have high death rates, the government decided to keep stocking H5N1 vaccines, not H1N1.

In 2013 in China, the H7N9 strain caused human infections and deaths.

The H5N1 strain, on the other hand, has become more diverse with its spread to many locations, including extensive areas of Asia and the Middle East, meaning vaccines may not be effective for some varieties.

Against this backdrop, a scientist proposed during a December meeting of a Cabinet Secretariat advisory panel that the current focus on stocking just the H5N1 strain be shelved.

Moves are underway to review Japan’s decade-old casualty estimation because it serves as the basis for whatever measures are taken.

A research team led by Hiroshi Nishiura, a professor of infectious disease epidemiology at Hokkaido University, is planning to draw up an updated damage scenario taking into account multiple conditions.

It will also be based on estimations and analyses by experts in various fields.