Breakthrough cases of polio—including deaths—were common during early polio vaccination.
— Michael Clemens (@m_clem) September 28, 2021
What kept us safe was not perfect vaccine efficacy. It was that Americans quickly & massively stepped up to get the imperfect vaccine, quashing transmission.
From: https://t.co/djYf0JmWnQ pic.twitter.com/PiGRHYcct6