Experts suspect cross immunity explains Japan’s low coronavirus death rate

June 14, 2020 (Mainichi Japan)

TOKYO — Some experts say cross immunity is the reason for the low death rate among novel coronavirus patients in Japan and other parts of Asia compared to that in Europe and North America.

When viruses that an individual has never been infected with enter the human body, the body makes antibodies, or proteins that combat the foreign substances. The first antibody to appear is Immunoglobulin M (IgM), while Immunoglobulin G (IgG) is produced later. While IgM antibodies disappear fairly quickly, IgG antibodies remain for a prolonged period and continue to protect the body from the same viruses.

When a team of researchers including Tatsuhiko Kodama, leader of the cancer metabolism project at the University of Tokyo’s Research Center for Advanced Science and Technology, studied the blood samples of coronavirus patients, IgG antibodies had increased in volume faster than IgM antibodies for some.

Kodama says this proves such people have immunity, since they were infected with a virus similar to the novel coronavirus that may have spread across Asia before. “Cross immunity may have worked when those people got infected with the new coronavirus,” he commented.

A team of researchers at the La Jolla Institute for Immunology in the United States has also pointed out that cross immunity may have worked for some people. According to a paper released by the American scientific journal Cell, researchers found immune cells that reacted to the new coronavirus from about a half of the blood samples collected from 20 people in the United States between 2015 and 2018.

Meanwhile, a separate research team including Yasuhiko Kamikubo, a program-specific professor at Kyoto University, provided a different explanation. They say because Japan was slow in closing its borders, a type of novel coronavirus with weak pathogen spread, and some people were already immune when the virus with strong pathogen spread later — which was why the damage is smaller compared to other countries.

Atsuo Hamada, professor of infectious diseases at the Tokyo Medical University, said, “If we have a clear understanding of the reason why there are gaps in the number of deaths in different countries and areas, we can understand how to respond to this infectious disease. Cross immunity due to the spread of a similar virus, mutation of the novel coronavirus and other factors to do with the virus itself are worth considering.”

(Mainichi)

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ロンドン、渋谷医師の論考（文春より）

はびこる「PCR検査拡大は不合理」説を公衆衛生の第一人者が論破！【偽陽性の問題はほぼ100％ない】

今から実行すべき「6 つの施策」

繰り返しになるが、今からでも遅くない。我が国も検査体制の徹底的拡大、検査と隔離の推進を基本戦略として明確に位置付け、感染制御と経済再生の両立に向けて、例えば以下のようなことを即座に実行すべきであろう。

1. 行政検査（保健所等の調査としての位置づけ）による調査の枠を外し、医師の判断のみで保険適
   用の検査（自己負担なし）を実施できるようにする。
2. 医療機関、介護施設等については、全てのスタッフが例えば 2 週間に 1 度 PCR 検査を受ける
   等の具体的なガイドラインを設け、費用負担等の点で支援をする。
3. 経団連等の経済団体に、感染状況の的確なモニタリングにも資することを踏まえ、企業の社員に
   ついて定期的に PCR 検査を実施することを要請する。
4. 医療機関が PCR 検査機器などを購入する際には 100％補助する。
5. 国産の PCR などの検査試薬と自動機器の開発製造基盤構築に対して、国が積極的な投資を行
   う。
6. 検査データの品質評価機関の設立と早期稼働により、信頼出来る検査データを公表し、世界の
   専門家が分析や政策提言等をできる枠組みを整備する。