noubar: thank you for having me back. is good news that we have begun to see some good evidence of antibody production -- protection lasting at least six months. we expect that, as we get more and more data, both from the earlier study in the larger studies that we did later in 2020. lots more to come on that, but that's encouraging. and as for the variants, our immune system is trained to detect many hundreds of threats on a daily basis. and, variants are going to look like slightly different threats. in some places, they have shown they can evade the immune response partially. but what we have shown so far is that some of the immune system continues to attack the variants, and we will have to keep a close eye on which variants are persisting. as you know, we have also started developing, just in case we need them, additional mrna vaccines that will target some of these variants. whether it's a variant vaccine or the original variant vaccine or some combination, we want to be one or two steps ahead of the virus. we want

matt: that was noubar afeyan, the cofounder of moderna. vaccine will start rolling out in the u.k. today. renewed concerns over astrazeneca shots. president biden says he wants all americans to be eligible for a vaccine by april 19. keep moving those goal posts forward, because the u.s. is doing so well in terms of rolling out the vaccine. let's go over to sam, who leads our pharma coverage. first, let's talk about how well the rollouts are going. as many people as there are adults in germany. it looks like. immunity should be reached -- it looks like herd immunity should be reached during the summer there. >> i think if they continue with that pace and get people fully vaccinated, then the u.s. can potentially be the first to achieve that number. amongst the bigger nations. mark: good morning. one of the things that concerns me is we are seeing a great improvement in the situation in the u.k.. but then i look at chile which is seeing no improvement despite similar levels of vaccinations. is the u.k. improvement really down to a lockdown?