A group of researchers in Japan say their clinical study of the anti-flu drug Avigan, a candidate for treating COVID-19, could not confirm statistical significance regarding its effectiveness.

Researchers at institutes including Fujita Health University in Aichi Prefecture conducted the study from March to check the drug's effectiveness and safety.

Professor Doi Yohei at the university published the results of the study in an online news conference on Friday.

The researchers used Avigan on 88 patients infected with the virus and having mild or no symptoms.

The patients were divided into two groups. One was given Avigan from the first day for up to 10 days. The other was given the drug from the sixth day.

The researchers say the results show that as of the sixth day, the virus was not detected in 66.7 percent of the patients in the group given Avigan from the start.

The figure was 56.1 percent for the group on which the drug was not used in the first five days.

The study also shows that it took an average of 2.1 days for the temperatures of those in the first group to return to normal. For those in the second group, it took 3.2 days.

The researchers say they found that patients given the drug from the first day showed no sign of the virus and returned to normal temperature sooner than those who were not.

Although the researchers could not confirm statistical significance regarding the drug's effectiveness, Doi said the results show the drug caused improvement sooner. They also said they found no serious side effects.

Doi said he will offer the data to the government if requested.