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4 data points showing Arizona is past the omicron peak

Positivity rates
Posted at 9:20 PM, Jan 31, 2022
and last updated 2022-01-31 23:20:57-05

PHOENIX — In some good news, COVID-19 cases appear to be on the decline in Arizona.

The state is now averaging 14,763 new cases on a seven-day moving average, a decrease of 28.9% from the same day last week.

Here are four data points indicating that Arizona is very likely past the omicron surge.

Positivity rate is falling

The rate at which diagnostic COVID-19 tests come back positive is seeing a meaningful decline.

New testing data added to the state’s totals over the weekend shifted the past six days to an under 30% positivity rate.

The positivity rate by day the test was taken reached a peak on Jan. 23, when 37% of tests came back positive. Jan. 27, the most recent day with a large volume of tests, currently has a rate of 26%. This is a welcome sign as a declining positivity rate is a good leading of community spread.

The availability of at-home tests has dented this somewhat, but the long-term pattern of the positivity rate rising and falling with the number of confirmed daily cases continues to be persistent.

Omicron is following the same pattern as the alpha surge

Last year’s surge brought about by the UK variant, also known as alpha, peaked on Jan. 13, 2021, about 12 days earlier than this year’s omicron-fueled surge.

After last year’s peak, cases fell consistently until the middle of April when the more transmissible delta became dominant in the state.

Right now, omicron cases are declining faster — a 29% decrease in seven days compared to a 27% decrease last year in the same time frame.

Rate of transmission is under one

Arizona’s Rt, the rate of COVID-19 transmission over time, is estimated to be at 0.93. The Rt represents the number of people that a person infected with COVID-19 can transmit the virus to, so any value under 1 means that the pandemic is expected to continue shrinking.

Arizona is one of 23 states to have an Rt value below 1. The lowest estimate belongs to Hawaii (0.46). Oklahoma currently is considered the highest at 1.6.

Modeling predicts cases will halve every 15 days

Modeling from the University of Washington forecasts that the daily average of confirmed cases in Arizona will drop by about half, to 5,095, by the middle of February, followed by another halving of the daily average by early March.

The model predicts that the state will drop below 100 confirmed daily average cases by early May.