Delta still dominates say experts urging third jab
Contact tracing revs up in some states as omicron reaches US
4 December 2021US drugstores squeezed by vaccine demand, staff shortages
4 December 2021Delta still dominates say experts urging third jab
No one knows how effective vaccines will be in stopping people catching the newly discovered and fast-spreading Omicron variant of COVID-19 or how well they will protect against severe illness.
