Omicron Infection and Excess Mortality  - Director's Blog



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Omicron Infection and Excess Mortality 

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While symptoms of the Omicron virus are said to be milder than those of the usual Delta variant, many people are worried about contracting the Omicron virus which has high daily death rate. However, at present, about 70 to 80 percent of the deaths due to the Omicron virus are said to be mainly elderly people with medical conditions such as diabetes, kidney disease, and heart disease.* Regardless of whether or not there are underlying conditions, it is quite sensible and understandable to be concerned about the large number of deaths resulting from Omicron virus infection.

However, if the Omicron virus is not viewed as the direct cause of death in those who have underlying conditions, the picture looks very different.

The reason that I bring this topic up is that the deaths due to infection by the Omicron virus at present closely resemble the "excess mortality" that results from influenza infection.

In some cases, influenza infection, like acute encephalopathy in infants, also has a high mortality rate due to infection of the brain by the influenza virus. However, we now know that in the case of people who die from influenza during the season, influenza infection is not the direct cause of death, but rather in many cases, it is due to complications such as bacterial pneumonia. This influenza infection is not the direct cause of death, but when death is caused by a combination of the aggravated underlying condition and pneumonia due to infection, it is called "excess mortality" due to influenza.

During the 2019 flu season prior to the COVID-19 epidemic, the number of deaths due to (directly caused by) influenza infection reached 3,575, and the excess mortality numbers are said to have been approximately 10,000.

Currently, if a person who has died due to an Omicron variant shows positive results for an Omicron variant in PCR and antigen tests, the case will be considered "death due to the Omicron variant" regardless of underlying conditions and the degree of severity.

Severe pneumonia, which has a high fatality rate, was the leading immediate cause of death in cases of infection by the Delta strain variant, but only in a few cases of infection by the Omicron variant. Only four deaths due to the Omicron variant have been reported among children under 10 years of age. This has been attributed to differences in basic physical functions between children and the elderly, but it appears to be largely related to whether the person also has underlying conditions.

The responses to questions about whether the Omicron variant is the direct cause of death provide important hints regarding the treatment of young people who do not have an underlying disease or condition. Temporarily closing kindergartens, daycare centers, and schools may be unnecessary where the majority of students are children who do not have an underlying disease or condition. Furthermore, this is where we will begin to approach an answer in the current debate regarding the reasons in favor of or against vaccination of children. It is not possible to state with certainty, but it is my personal view that in the vaccination of children, those with an underlying health condition should be given priority.

* NHK, "The Omicron Variant: In the 6th Wave, Nearly 80% Have an Underlying Health Condition in Tokyo". February 16, 2022. (in Japanese)
sakakihara_2013.jpg Yoichi Sakakihara
M.D., Ph.D., Professor Emeritus, Ochanomizu University; Director of Child Research Net, Executive Advisor of Benesse Educational Research and Development Institute (BERD), President of Japanese Society of Child Science. Specializes in pediatric neurology, developmental neurology, in particular, treatment of Attention Deficit Hyperactivity Disorder (ADHD), Asperger's syndrome and other developmental disorders, and neuroscience. Born in 1951. Graduated from the Faculty of Medicine, the University of Tokyo in 1976 and taught as an instructor in the Department of the Pediatrics before working with Ochanomizu University.