@mskathleenquinn @greg_travis US and UK were mostly a natural immunity strategy. Vaccines were expected to be too late and not that effective. Goal was to MAXIMIZE infection to speed up herd immunity. Trials went much faster than expected (due to high community spread) and results were better than expected.
@mskathleenquinn @greg_travis 美国和英国主要是一种自然免疫策略。预计疫苗为时已晚，而且效果不佳。目标是最大化感染以加速群体免疫。试验进行得比预期快得多（由于社区传播程度高），结果也好于预期。