Arizona is now solidly amid another substantial surge in cases, hospitalizations, and deaths. If sustained, the surge could exceed rates last seen during the summer of 2020, 409 cases per 100K residents per week. Except for Mississippi, 4-of-the-5 other states with the highest transmission rates now have stable or declining rates. Current rates for Mississippi, Louisiana, Florida, Arkansas, and Alabama are 843, 785, 664, 488, and 422 cases per 100K residents per week, respectively. Arizona’s level of transmission now ranks 22nd among the 50 states.

According to the CDC, 57% of Arizona adults have received 2-doses of vaccine while another 10% have received 1-dose. While vaccinations have plateaued at 90 thousand doses per week, vaccine outreach remains important. Individual and community non-pharmacologic interventions like mask mandates, limiting gathering sizes, and targeted business mitigations are still needed to ensure this surge doesn’t intensify.

Resumption of in-person instruction in the face of high community transmission, low vaccination rates, prohibition of universal masking, lack of surveillance testing, and minimal physical distancing is leading to frequent school-related outbreaks and has the potential to accelerate community transmission. On a positive note, several K – 12 and university systems are challenging the governor’s prohibition of mask mandates.

Figure 2a above shows that transmission among children (dotted) is poised to surpass the rates of older age groups for the first time in pandemic history. The combination of increased transmissibility (Delta variant), resumption of in-person K – 12 instruction, and prohibition of effective non-pharmacologic measures (e.g., masking and testing) is causing transmission among children 5 – 14 years to accelerate (Figure 2b). In coming weeks, case rates are expected to increase among those 15 – 24 years as universities also re-open.

While transmission among adolescents and working-age adults remains high, rates among those aged 5 – 9 years and 10 – 14 years surpass those of other age groups for the first time during this pandemic (Figure 2c). Transmission rates among those 5 – 9 years is now 89% of their prior peak whereas transmission rates among those 10 – 14 years is 73% of their prior peak. To protect children, we must slow transmission among adults and institute more effective non-pharmacologic interventions in school settings.

Vaccination, and now, K – 12 re-opening is shifting the age distribution of cases away from older adults towards children (Figure 2d). Children now represent about 25% of cases, up from 10% during the winter 2020 outbreak, while older adults now represent about 8% of cases, down from 15% during the winter 2020 outbreak.

To create a mental frame, it is helpful to compare our current circumstances to those previously experienced. Comparing school reopening this year (in-person) with last year (virtual), levels of community transmission are much higher this year (Figure 2e).

By comparing two different time periods with similar levels of transmission (August 15, 2021 and November 15, 2020), a shift towards younger age at time of diagnosis becomes apparent (Figure 2f). The most striking increases have occurred among those 40 years of age.

Until this week, there was a high degree of concordance between the trajectory of our current outbreak and that of the winter 2020/2021 outbreak (Figure 2g). With this week’s slowing, there is a suggestion that the two curves could be diverging. Because the past outbreak was marked by temporary retreats followed by renewed charges, it is too early to tell whether this week was an aberration or a harbinger of a sustained change.

Another consideration is how testing availability and priority has changed over time. The number of tests performed and test positivity by age group for two different time periods with similar levels of transmission are presented in Table 1. Among children, there is considerably more testing now than in November 2020 whereas the reverse is true for adults. All groups have higher test positivity now than last November. Taken together, it seems possible that more children and fewer adults might be identified now as compared to last November owing to differential testing. However, the differences are not so large as to think higher transmission among children is solely an artifact of increased testing.

Test positivity among those undergoing traditional nasopharyngeal PCR testing dropped this week to 21% (Figure 3). This level indicates testing is inadequate for optimal public health practice and means many cases are going undiagnosed. Prior peaks in test positivity have preceded peak transmission rates by 1 week. Historically, peak test positivity has preceded peak transmission by 1 week. This provides some additional indication that slowing transmission could reflect a sustained change.

As of Aug 18th, 1837 (21%) of Arizona’s 8762 general ward beds were occupied by Covid-19 patients, a 20% increase from the previous week’s 1527 occupied beds (Figure 4 and Figure 5 Panel A). Another 717 (8%) beds remained available for use. The number of available beds is lower than the previous week’s 797 beds.

As of August 18th, 432 (25%) of Arizona’s 1758 ICU beds were occupied with Covid-19 patients, a 13% increase from the prior week’s count of 383 patients (Figure 4 and Figure 5 Panel B). An additional 189 (11%) ICU beds remained available for use, a bit higher than last week’s 174 beds.

Arizona hospital occupancy remains above seasonal levels and we are now seeing the first indications that our safety margin as measured by excess, available ward and ICU beds is eroding (Figure 6). Undoubtedly, some medically necessary procedures will likely be postponed and rescheduled over the coming weeks to make room for critically ill COVID-19 patients. Hospitals should be prepared for >20% COVID-19 ward occupancy and >25% ICU occupancy for the foreseeable future. Even if you are vaccinated, the COVID-19 surge can impact your health should you become ill and required hospital care. In the essence, care will become increasingly more rationed over the coming weeks with only the sickest of the sick being able to access critical care services.

While the week ending January 17, 2021 remains Arizona’s deadliest with 1093 deaths, we are once again seeing >100 COVID-19 deaths per week. The week ending August 1st tallied 126 deaths so far with a few more likely to be recorded in the coming weeks. Given weekly tallies of 18 - 20000 cases, it is possible we will see approximately 300 deaths per week by the end of August if the case fatality rate remains consistent at approximately 1.5%.

Despite high vaccination rates among those >65 years of age, most deaths are still attributable to infections among this medically frail group (Figure 7b).

For the week ending August 8th, 1804 Pima County residents were diagnosed with Covid-19 (Figure 8). This is a 2% increase from the 1762 cases initially reported last week.

New cases are being diagnosed at a rate of 172 cases per 100K residents per week. This rate is increasing by 2 cases per 100K residents per week. Trends across the various age groups appear in Figure 9 (Note: the abrupt downturn among working-age adult is a bit suspicious).