The WHO released its landscape of the COVID-19 vaccine environment, and it provides some updated data on vaccine timelines as well as a full list of compounds in development. While there still is much to be debated on about the science, the timelines in question are just as important - as the summer is ending, schools are going back in session, and countries like South Korea, Vietnam and New Zealand (that handled original outbreaks very well) are facing spikes again, we are still in need of a vaccine if we don't revert back to stricter lockdown measures.
The science behind the vaccine is important - there are different vectors to use to develop a vaccine to fight COVID-19, and the six vaccines in Phase 3 trials are using three different vector types - three inactivated, one non-replicating viral vector, and two RNA. Each different vector type has different advantages and disadvantages when it comes to development, safety, efficacy and dosages.
While there is much to be said about the science, with 29 candidates in clinical stages (six Phase 3, two Phase 2, 10 Phase 1/2, and 11 in Phase 1) and 138 in preclinical evaluation, a lot of weight rests on just when the vaccines could be available. To read more about the science, early phase data in the leading candidates, vector differences, and more, refer to my previous article here, as this one will focus on the timelines in play.
Overall, of the vaccines in trials, only five so far are single dose - Oxford/AstraZeneca's (AZN) ChAdOx1-S is the only in Phase 3 trials, while CanSino/Beijing's Ad5 vector is in Phase 2. The remaining three are still in Phase 1 trials, far behind much of the pack here. With a majority requiring a double dosage at 0 and either 14, 21 or 28
