Covid vaccine roundup: US vaccine supplies grow, but experts warn of potential hiccups in supply chain; Emergent touts growing Covid vaccine capacity

The Biden administration has been raising hopes in the US that there will be ample vaccine supplies to inoculate more than 250 American adults by May. There have been new deals with Moderna and Pfizer to ramp up 400 million doses, to cover 200 million, with 100 million single-shot vaccines from J&J top finish the job.

But some experts are sounding a warning that there could be a lot more to this than simply signing contracts. Vaccine manufacturing is not an easy business.