ワクチン、重症化予防にかなり有効だが１００％ではない。

ケンタッキー州の老人ホームでファイザーを二回接種していても、ワクチンをしていないケアワーカーからクラスターが発生してワクチン接種していた人の死亡例も出たようなので、ワクチンは完璧ではないし、医療関係者や介護士のワクチンも本当に大事。　https://t.co/0aB9t8oDfN

— kazukazu88 (@kazukazu881) May 17, 2021

ケンタッキーではなく、シカゴみたいだね。 

In Chicago, meanwhile, routine screening of nursing home residents and staff members identified 627 coronavirus infections in 78 skilled nursing facilities in the city in February, but only 22 were found in individuals who were already fully vaccinated. Two-thirds of the cases in the vaccinated individuals were asymptomatic, the report found, but two residents were hospitalized, and one died.

Postvaccination SARS-CoV-2 Infections Among Skilled Nursing Facility Residents and Staff Members — Chicago, Illinois, December 2020–March 2021 Weekly / April 30, 202

What is added by this report? Twenty-two possible breakthrough SARS-CoV-2 infections occurred among fully vaccinated persons ≥14 days after their second dose of COVID-19 vaccine. Two thirds of persons were asymptomatic. A minority of persons with breakthrough infection experienced mild to moderate COVID-19–like symptoms; two COVID-19–related hospitalizations and one death occurred. No facility-associated secondary transmission was identified.

ワクチン、かなり有効だが１００％ではない、ということだろうね。