system hasn't quite worked out as well as some had hoped. i want to ask you about the response from the biden administration. the u.s. government purchasing an additional 200 million doses of the pfizer vaccine this week. they're going to continue to be delivered through april of 2022. a reminder the pandemic isn't over. especially because in that announcement the united states has an option to receive an updated version of the vaccine to address it. >> we know the vaccines have a chef life. the more the need is to update and get more vaccine in their stead. the big picture is though what this virus is telling us it can do, it's telling us it can change and evolve. we're dealing with the worst strain yet. alongside the fact people are choosing not to get vaccinated.