Omicron, seasonal flu have similar mortality rates among people 80 or older, Japan health ministry finds

The Yomiuri Shimbun

7:00 JST, December 23, 2022

The mortality rate for the omicron variant of the novel coronavirus among people aged 80 and over is very close to that for seasonal influenza, the health ministry has announced.

When the omicron variant was prevalent in July and August this year, 1.86% of infections among people 80 and older developed into severe cases, and 1.69% ultimately proved fatal, according to the ministry. This compared to 2.17% of seasonal influenza cases becoming serious in this age group and 1.73% ultimately succumbing to the disease.

These calculations used data from Ibaraki, Ishikawa and Hiroshima prefectures for the omicron variant and national data for seasonal influenza. The ministry’s findings were presented at a Wednesday meeting of an advisory body.

Some experts have said the mortality rate of the omicron variant may be underestimated and cannot be simply compared to that of seasonal influenza. However, the government will refer to this data when reviewing the categorization of COVID-19 under the Infectious Diseases Law.

According to the data, when the BA-5 omicron variant was spreading rapidly in July and August, 0.01% of infections developed into severe cases among people under 60 years old, compared to 0.26% of cases among people aged 60 to 79.

Omicron’s mortality rate was essentially zero for people under 60 and 0.18% for those aged 60 to 79, putting it very close to the seasonal flu’s mortality rate of 0.01% for people under 60 and 0.19% for those aged 60 to 79.

During the prominence of the delta variant from July to October last year, 10.21% of infected people aged 80 and older became severely ill, and the mortality rate was 7.92%.

The omicron variant is believed to be less virulent than other forms of the coronavirus, and efforts to vaccinate the public are believed to have increased the number of people with resistance to the disease.

The government is considering lowering the novel coronavirus’ ranking on its five-tier categorization of infectious diseases, from the current Category II equivalent to Category V, on par with the flu.

However, experts caution that it is not appropriate to base the decision on a direct comparison of mortality rates and other data, due to different methods of tallying data.