[ad_1] <br><img src="https://cdn.cnn.com/cnnnext/dam/assets/200713194144-pfizer-biontech-vacuna-covid-farmaceuticas-dosis-constanza-directora-perspectivas-mexico-entrevista-vo-00005430-hp-video.jpg" /><br>Pfizer proposes expanding Covid-19 vaccine trial to include more diversity <br>[ad_2] <br><a href="https://cnn.it/32plRIB">CNN </a>
