$Pfizer (PFE.US)$$AstraZeneca (AZN.US)$ An analysis of 581 c...

$Pfizer (PFE.US)$ $AstraZeneca (AZN.US)$ An analysis of 581 cases of omicron infection showed that two doses of Either Astrazeneca or Pfizer vaccine provided much less protection against this strain than against the Delta strain. However, when given the Pfizer booster shot, patients who initially received the Astrazeneca vaccine had about 70% protection against symptomatic infections, compared with about 75% when initially given the Pfizer vaccine. By comparison, the booster vaccine was about 90% effective against the Delta strain.