Delta vs. omicron surge: A comparison of key trends

Becker's has compiled some key U.S. COVID-19 metrics from both the delta and omicron surges. 


During the delta surge, U.S. COVID-19 cases peaked in September, with the seven-day case average hitting 164,374 per day on Sept. 2, according to data tracked by The New York Times. In comparison, omicron cases appeared to peak Jan. 15, with the seven-day case average hitting 806,801 new daily cases. 


During the delta surge, COVID-19 hospitalizations hit a seven-day case average of 102,782 patients hospitalized Sept. 4, according to data tracked by the Times. In comparison, virus hospitalizations hit their highest level of this surge yet on Jan. 20, with an average of 159,495 patients hospitalized.


The nation's COVID-19 death averages are rising, now eclipsing levels seen during the delta wave, data from Baltimore-based Johns Hopkins University shows. 

According to a Jan. 26 report from The Washington Post, current COVID-19 death averages hit their highest levels since early 2021. The seven-day average for new daily virus deaths reached 2,230 on Jan. 25.

Current COVID-19 deaths mirror or surpass levels seen during the delta surge, when deaths peaked just above 2,100 in late September. This average still falls below levels seen in mid-January 2021, before vaccines were widely accessible. 


Two separate studies published by the CDC Jan. 21 explored vaccine and booster dose effectiveness against the periods in which delta and omicron were emerging and predominant.

Estimates of vaccine effectiveness against COVID-19 declined during the omicron-predominant period compared to the delta-predominant period. During both delta and omicron periods, receipt of a third vaccine dose was highly effective (94 percent and 82 percent, respectively) at preventing COVID-19 emergency department and urgent care encounters and preventing hospitalizations (94 percent and 90 percent).

The effectiveness of two mRNA vaccine doses were higher against COVID-19 hospitalizations than against ED or urgent care encounters, especially amid omicron.

Differences in case rates between fully vaccinated people with and without a booster dose decreased over time; however, more protection was afforded from booster doses, even during omicron emergence. 

Case and death rates were consistently higher in all periods among unvaccinated Americans. 


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