1. How well does the vaccine work against known variants? The data shared this morning did not provide insight into how well the vaccine works against variants of Covid-19 and did not provide a breakdown of efficacy by country. That data will provide key insight into the vaccine's effectiveness against variants—and might even help guide future vaccine deployment and allocation efforts across the globe. 

1. How well does the vaccine work in different patient demographics and subpopulations? AstraZeneca's study was slightly less racially and ethnically diverse than other Phase 3 vaccine trials for Covid-19. Participants were 79% white, 22% Hispanic or Latino, 8% Black, 4% Native American, and 4% Asian. In addition, 20% of participants were 65+ years old and 60% had comorbidities. In the coming weeks, we'll be looking for additional data that assesses efficacy in these different populations. 

1. Will the U.S. reallyneed AstraZeneca's vaccine by the time it is authorized? Given the accelerating pace of the vaccine rollout in the United States and lingering pockets of hesitancy, it's possible that the steady supply of Pfizer, Moderna, and J&J's vaccines will exceed weekly demand for vaccines in the U.S.by the late spring.The U.S has already agreed to share 4 million doses of AstraZeneca's vaccine with Mexico and Canada, but some experts are calling for the U.S. to donate even more supply to other countries, recognizing the potential for excess. However, the implications of this remain unclear. 

1. Will an emergency use authorization for Astra-Zeneca's vaccine increase patients' likelihood to vaccine shop for the brands they perceive to be the "best"? Across the country, vaccine sites are increasingly transparent in telling the public which vaccine they offer and when. Given recent confusion over the AstraZeneca vaccine's safety in other parts of the world, it's likely that some patients might opt for a vaccine other than AstraZeneca's, if given the ability to choose (and if the vaccine is authorized).

Communication about the vaccine will be essential to building public confidence and trust

AstraZeneca's previous trial and rollout pauses—including February's trial halt in South Africa due to concerns about the efficacy against new variant, last September's trial pause due to a unexplained illness, and last week's rollout pauses in the EU due to blood clot concerns—have exacerbated skepticismand confusion about vaccines.