Test positivity declined for the first time in a while to 55% (Figure 3). Now that cases, testing, and positivity are all declining, the Omicron peak is all but certain. However, other jurisdictions have seen a follow-on “bounce” wave, smaller than the first, due to relaxing mitigation and perhaps the new more transmissible BA.2 Omicron variant. We should expect the ride down the backside of the peak to be bumpy.

As of January 27th, 3559 (41%) of Arizona’s 8767 general ward beds were occupied by COVID-19 patients, a 4% increase from last week’s 3410 occupied beds (Figure 4 and Figure 5 Panel A). Another 405 (5%) beds remained available for use which is much lower than last week’s 492 available beds. Six-hundred thirty-six (636, 39%) of Arizona’s 1648 ICU beds were occupied by COVID-19 patients, a 7% increase from last week’s 597 occupied beds (Figure 4 and Figure 5 Panel B). An additional 92 (6%) ICU beds remained available for use which is lower than last week’s 127 beds.

While peak occupancy won’t reach prior levels, we remain above 4000 combined occupancy for only the 3rd time. The overlapping Delta and Omicron waves have placed hospitals under greater strain than prior waves. We have now experienced 167 consecutive days with a combined occupancy >2000 patients whereas the summer 2020 and winter 2021 saw 57 and 98 days, respectively. We have now experienced 62 days with >3000 combined occupancy whereas the summer 2020 and winter 2021 waves saw 35 and 78 days, respectively. Just like Wile E Coyote, hospitals are getting crushed by a slow rolling steam roller. No end in sight.

Hospital occupancy remains far above seasonal levels with safety margins, as measured by available beds, remaining near historical lows (Figure 6). Hospitals should prepare for >30% ward occupancy and ICU occupancy through February.

Seasonal influenza cases in Arizona (blue line) has fizzled, at least as compared to the state’s 5-year historical average (grey bars, Figure 7). COVID-19 mitigation efforts may have slowed influenza transmission. Hospitals should begin to get relief from fewer COVID-19 and fewer influenza cases over the coming weeks.

The week ending December 12^th has now recorded 542 deaths to date. Hopefully, this will be the only week this happens during the Delta - Omicron waves (Figure 8a). At least 26001 Arizonans have lost their lives to COVID-19. A mortality report from the AzPHA indicates that official statistics undercount actual deaths.

Figure 8b shows age-specific case-fatality rates (CFR) by year. Crude CFR is subject to surveillance bias for both cases (large undercounting) and deaths (modest undercounting). The bias may differ by age The impact of vaccination is most apparent for those >55 years whereas crude CFR was the same or a bit higher in 2021 than 2020 among working age adults.

The age-standardized CFR has remained remarkably stable between 1.5 – 2.0% for over a year (Figure 8c). The CFR is standardized to a case age distribution the week of October 25, 2020.

The proportion of COVID-19 deaths among the elderly (≥60 years) and eldest, elderly (80 years) both fell in March 2021 following the targeted vaccination campaign (Figure 8d). However, deaths have since returned to pre-vaccine levels for those >60 years, but not among those >80 years. This suggests deaths shifter younger in the >60 demographic and away from those >80 years.

Because I have the room, I thought I would throw in one more figure. Figure 8e shows the ratio of the daily COVID-19 ward and ICU census. Typically, when cases increase rapidly ward occupancy increases relative to ICU occupancy. This trend was considerably more pronounced with the Omicron wave likely due to its lower severity.

For the week ending January 23rd, 17055 Pima County residents were diagnosed with COVID-19, a 2% increase from the initial tally of 16669 cases last week (Figure 9).

Depending on backfill, this week or last will likely be Pima County’s peak. Transmission by age group is shown in Figure 10.