新加坡的study 發現Pfizer和moderna疫苗對delta 變種有效，具體細節見內。

這個study 全都是看染delta變異住院的病人。打過疫苗又感染的人年紀比較大（中間值56歲），沒打疫苗的中間值是39.5歲； 打疫苗的人前5天viral load和沒打的一樣高，然後快速下降。打疫苗無症狀的多，有症狀也比較少。沒打疫苗的有比較高的嚴重疾病的biomarker。

打疫苗的breakthrough case 和不打疫苗的比，97%有效不得（需要氧氣的）重症或中症（肺炎）

https://www.news-medical.net/news/20210802/Study-shows-efficacy-of-Pfizer-BioNTech-and-Moderna-vaccines-against-SARS-CoV-2-delta-variant.aspx

The team found that individuals fully vaccinated with either Pfizer-BioNTech’s BNT162b2 vaccine or Moderna’s mRNA-1273 product were significantly less likely to develop moderate or severe outcomes following B.1.617.2 infection than unvaccinated individuals.

Vaccination was associated with fewer symptoms, lower peak biomarkers of systemic inflammation, and better clinical outcomes. It was also associated with a more rapid decline in viral RNA load and a robust serologic response.

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Multivariate logistic regression analysis revealed that vaccinated individuals were 97% less likely to develop severe COVID-19 that required oxygen supplementation or moderate disease (defined as development of pneumonia).