To kick-off the conversation with @BillGates, what scientific or tech breakthrough would make the biggest difference now to ending the COVID pandemic?

@devisridhar The vaccines we have prevent severe disease and death very well but they are missing two key things. First they still allow infections ("breakthrough") and the duration appears to be limited. We need vaccines that prevent re-infection and have many years of duration.#

@BillGates Agree 100%- next gen vaccines with sterilising immunity. 2nd question: What are the current challenges in reaching global vaccination access? What are the obstacles?

@devisridhar During 2021 the supply of vaccines was limited and they mostly went to wealthy countries. Now we have a lot of supply overall and the problems are logistics and demand. The health systems in developing countries are a limiting factor.

@devisridhar mRna vaccines still can't meet all the demand so figuring out who gets what is complicated.#

@BillGates There's been a lot of discussion on responsibility of pharma companies like Pfizer/Moderna for access. What is the role of these companies in ensuring pricing and availability esp in low and middle income contexts?

@devisridhar When we have adequate supply then tiered pricing is used where the rich countries pay a lot more than middle income and low income pay the least which is funded by @gavi. When supply is limited rich countries have to not outbid the others so governments are key to this. #

@BillGates @gavi Looking back on 2020/21 (and given you warned of a respiratory pandemic for years before), what do you think is the biggest mistake most countries (with resources) made in responding?

@devisridhar @gavi A few countries like Australia moved fast to diagnose cases at scale and isolate people who were infected. They were able to limit deaths dramatically. Once the numbers get large in a country it is too late. So the first few months made a lot of difference.

@devisridhar @gavi Also some countries did a better job of reducing mobility, using masks and protecting the elderly. We weren't prepared - no practice in advance.#

@devisridhar @gavi Do you think the world will come together to get ready for the next one? I hope so but I am not sure.#

@BillGates @gavi I'm optimistic about the '100 day challenge'- the idea of sequencing a new genome to developing diagnostics, therapeutics and effective vaccines- and getting them out to people. But requires leadership, planning & foresight. Now is the window to prepare.#