Why did Britain buy 3.5 million tests which might not work?

僕もファイナンシャルタイムズのオックスフォード大学の記事（英国人の半数が既にコロナウィルスに感染し過半の人が無症状か軽症で回復済みの可能性）を読み、「日本国民の60％以上が免疫をもち、集団免疫が成立している可能性がある」という仮説を持ち始めています。 https://t.co/CwyDvq94XZ

— 堀義人 (@YoshitoHori) March 26, 2020

オクスフォード大学の論文では「抗体検査などの技術への投資が緊急に必要だ」と提言し、イギリス政府は抗体検査キット350万人分を発注した。

Chief Medical

Officer Chris Whitty later dampened expectations of quick widespread availability for the tests, saying inaccurate tests would be dangerous.

“(The) technology is quite close, and it’s being evaluated this week, but it’s not there... The one thing that’s worse than no test is a bad test,” Whitty said.

“I do not think... that this is something we’ll suddenly be ordering on the internet next week.”

Asked why Britain bought 3.5 million tests which might not work, Prime Minister Boris Johnson’s spokesman said: “If we are able to find an antibody test which works that could be a game-changer.”

“For that reason you will understand that government is doing everything that it can to seek to find a test which works,” he added.

精度がわからなくてうまくいくかどうかわからないけど、とにかく発注しちゃった、政府は、できることすべてやっているんだよと。

A coronavirus blood test could be the key to beating the pandemic
Antibody tests could detect anyone who has previously been infected with Covid-19, letting us measure immunity and peel back social distancing regulations


By DAVID COX

Monday 23 March 2020

If a particular test is faulty – for example it also yields positive results for patients who have come into contact with one of the six other strains of coronavirus known to affect humans – then the results will be at best useless, and worst, potentially lead governments to make fatally flawed decisions, such as assuming herd immunity when it isn’t actually present.


Theel is particularly concerned about the emergence of serological tests, which are being falsely marketed by some unscrupulous companies. Last month virologists in Wuhan claimed they had developed a serological test which could diagnose Covid-19 in 15 minutes. Theel says such claims are misleading, because it takes between 8 and 11 days after infection for individuals to develop antibodies to the virus.

“More and more serological assays are coming out from manufacturers saying these can be used at the point of care,” she says. “But with that time delay, you don’t want to use these assays to diagnose acutely ill patients who are just starting to show symptoms. [...]. This is more of a retrospective method. We need to make sure that the intended use is clearly stated to clinicians.”

Comparisons between Covid-19, and OC43 and HKU1 – two of the four coronaviruses that regularly circulate among humans and cause seasonal colds – suggest that immunity could be relatively short-lived. Humans infected with OC43, for example, stay immune for less than a year. On the other hand, immunity against the SARS virus from 2003 lasts for far longer.

精度が悪いと役にたたないどころか、政府が間違った方針をたててしまう。武漢で、１５分でコロナ検診できるキットができたとか宣伝しているのがあるが、抗体ができるまで、８日から１１日かかるので、そうした宣伝は誤解を与えるものだ、と。
（ちなみに、免疫が仮にできたとしても、それが１年もたないものもあるわけですね。）


Has half the UK already caught COVID-19? Probably not.
By Nicoletta Lanese - Staff Writer 2 days ago

A new study rests on several big assumptions, but highlights the desperate need for antibody testing.

オックスフォードの論文はいくつかの前提の上に結論付けらているが、その前提・想定がいかがなものか、と。

To begin, the authors write that their overall approach "rests on the assumption that only a very small proportion of the population is at risk of hospitabitable illness.


"As far as I can tell, the model ... assumes that all those infected, whether they are asymptomatic, mildly ill or severely ill are equally infectious to others,"

In addition, the model assumes that the U.K. population would become "completely mixed" over time, meaning any given individual has an equal chance of running into another within the region, Hunter wrote.


In comparison, a recent study from Imperial College London included numbers from several Italian villages where every resident received a diagnostic test and might provide more realistic benchmarks for the extent of infection elsewhere, lead author Niall Ferguson told the Science and Technology Committee, according to Wired U.K. "Those data all point to the fact that we are nowhere near the [Oxford study] scenario in terms of the extent of the infection," Ferguson said.

専門的なことでよくわからんが、感染して入院する人の割合の想定が少ないし、感染した人の感染力は同じだという前提にたっているし、感染した人々が地域で等しく交流するみたいな前提にたっているが、それがどうだか、と。

インペリアルカレッジの論文は、イタリアの村のケースを参照にしているが、それによると、われわれは、オックスフォードの論文のようなシナリオようには全然なっていない、と。

しかし、ともかく、抗体検査をするのは有意義だ、と。