乗組員ほぼ全員PCR検査して「陰性」を確認→17日間の航海で約85%の乗組員の新型コロナ感染確認。中和抗体保有者は感染防御効果あり?

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新型コロナウイルス_ワクチン情報 @VaccineWatch

アメリカから興味深い報告(プレプリント)。 5月に米国シアトルを出発した漁船で、乗組員122名の内104名(約85%)が感染した船内アウトブレイク。乗組員はほぼ全員(120名)が出発前にPCRで陰性を確認していたにも関わらず17日間の航海でアウトブレイクとなった。やはりPCRスクリーニングは万能では無い。 twitter.com/jbloom_lab/sta…

2020-08-16 07:48:45
Bloom Lab @jbloom_lab

Excited to contribute to this extremely important #SARSCoV2 study by @GreningerLab that provides first direct evidence that neutralizing antibodies are a correlate of protection against #COVID19 in humans! (1/9) medrxiv.org/content/10.110…

2020-08-15 06:00:21
Bloom Lab @jbloom_lab

Excited to contribute to this extremely important #SARSCoV2 study by @GreningerLab that provides first direct evidence that neutralizing antibodies are a correlate of protection against #COVID19 in humans! (1/9) medrxiv.org/content/10.110…

2020-08-15 06:00:21
新型コロナウイルス_ワクチン情報 @VaccineWatch

興味深いのは、出発前に採取した血液で抗体陽性だった6名のうち、中和活性があった3名(つまり免疫があった)は、船内アウトブレイクにも関わらず、下船後の検査で感染が確認されなかった。つまり、中和抗体は完全防御と相関していることが示唆された。中和活性のない他の3名は全員感染していた。

2020-08-16 07:48:45
新型コロナウイルス_ワクチン情報 @VaccineWatch

中和抗体の存在が乗船前に確認されていたのが僅か3名なので、データがある他の117名との直接比較は難しいが、乗船前の時点で中和抗体陰性だった被験者との間には統計的には有意な差があった pic.twitter.com/nh8sLXCucd

2020-08-16 07:48:47
拡大
新型コロナウイルス_ワクチン情報 @VaccineWatch

この論文から示唆されるのは、 1)中和抗体が誘導されていれば感染防御効果があると推定される 2)ワクチン投与後に中和抗体が確認できれば、恐らく感染防御効果があると推測できる 3)PCRスクリーニングで陰性を確認していても油断できない(感度の問題)

2020-08-16 07:48:47
新型コロナウイルス_ワクチン情報 @VaccineWatch

毎度のことながら、プレプリントの発表なので未査読のため注意してください。また、被験者の数も決して多くはないし、特に中和抗体が確認できていたのは僅か3名なので結果の解釈には慎重にならないといけません。 プレプリントのリンクはこちら。 medrxiv.org/content/10.110…

2020-08-16 07:48:48
新型コロナウイルス_ワクチン情報 @VaccineWatch

しかし全体の85%の人が感染してしまうとは恐ろしいですね。漁船という3密状態では、一人でも感染者がいるとアウトブレイクになってしまう。しかもPCRで陰性を確認しているにも関わらず、です。 色々と考えさせられる報告でした。

2020-08-16 07:48:48
新型コロナウイルス_ワクチン情報 @VaccineWatch

「完全防御」ではなく「感染防御」のタイポです。失礼しました

2020-08-16 09:05:38

Bloom Lab @jbloom_lab

Excited to contribute to this extremely important #SARSCoV2 study by @GreningerLab that provides first direct evidence that neutralizing antibodies are a correlate of protection against #COVID19 in humans! (1/9) medrxiv.org/content/10.110…

2020-08-15 06:00:21
Bloom Lab @jbloom_lab

Perhaps *the* most important question in the #SARSCoV2 field right now is what immune responses protect against re-infection in humans. Knowing the answer to this question is critical for vaccine design and epidemiology. (2/9)

2020-08-15 06:00:22
Bloom Lab @jbloom_lab

Lab studies show neutralizing antibodies are protective in animals, but there isn't comparable data in humans. To address this, large & expensive studies are currently being set up. But @GreningerLab came up with a creative way to start answering this question right now! (3/9)

2020-08-15 06:00:22
Bloom Lab @jbloom_lab

In May, a fishing boat with 122 passengers on its manifest left port in Seattle. To avoid a #SARSCoV2 outbreak on board, nearly all crew (120 / 122) were tested both for virus and for anti-N antibodies (Abbott assay) in tests run by UW Lab Medicine. (4/9)

2020-08-15 06:00:22
Bloom Lab @jbloom_lab

Unfortunately, there was still a #SARSCoV2 outbreak on board, and 103 of the 120 passengers with pre-boarding serology got infected. @GreningerLab realized it was possible to look back at pre-boarding serology to see if pre-existing antibodies affected who got infected. (5/9)

2020-08-15 06:00:22
Bloom Lab @jbloom_lab

6 of 120 passengers were positive for anti-N antibodies pre-boarding, & @khdcrawford @AdamDingens in our lab determined just 3 of 6 had anti-Spike & neutralizing antibodies. (Of other 3, some may have been false positives in anti-N screening as low signal in Abbott assay) (6/9)

2020-08-15 06:00:22
Bloom Lab @jbloom_lab

So assuming that only individuals positive in anti-N Abbott assay have neutralizing antibodies (a good assumption, see pre-print for rationale), that means that 3 of 120 had neutralizing antibodies, and 117 of 120 did not (7/9).

2020-08-15 06:00:22
Bloom Lab @jbloom_lab

During the outbreak, 0 of 3 with the neutralizing antibodies were infected, and 103 of 117 without neut antibodies were infected. This is highly significant by Fisher's exact test. Therefore, neutralizing antibodies are correlate of protection in humans in this outbreak (8/9).

2020-08-15 06:00:23
Bloom Lab @jbloom_lab

Limitations: - neutralizing antibodies are *correlate* of protection, can't be sure they are causal vs some co-occurring immune response. - Only 3 individuals in neut antibody group and we can't be certain they were exposed, but result is statistically significant. (9/9)

2020-08-15 06:00:23