Daily admissions to Florida hospitals for confirmed adult and pediatric cases continue to double every 6.7 days.
We further update our comparison of the hospitalization curves for the Delta and Omicron waves in Florida. By day 15 from the initial appearance of each variant, statewide confirmed COVID-19 admissions among adults and children combined were running at about 250 per day. By day 34, however, Delta-wave admissions were 672, while Omicron-wave admissions have reached 1620. That’s nearly 2.5 time the number of admissions registered at the same point during this past summer’s wave.
Omicron-Related Hospitalizations Now Doubling Every 6.7 Days
Log-linear regressions on the data points from days 10 to 34 now give doubling times of 20.6 days for Delta and 6.71 days for Omicron. (The 95% confidence interval for the Omicron doubling time is 6.21 – 7.33 days.) As we have repeatedly stressed, these early findings do not necessarily mean that the Omicron curve will reach the Delta peak of 2,360 statewide hospital admissions attained on August 17, 2021 (that is, day 68 from initial appearance).
Hospitalization Rates Matter.
Public officials and some commentators have noted that COVID-19 hospitalization rates are not rising nearly so fast as total case counts. The fact that hospitalization-to-case ratios are now lower than during the past summer’s wave has been highlighted as favorable news. With rapid home-based COVID-19 tests now in abundance, it is unclear what case counts reported by public health departments are supposed to represent.
We continue to focus here on severe disease and its impact on our already stressed healthcare system.
As we’ve repeatedly noted, we do not have data on the variant underlying each hospital admission. Still, according to the most recent CDC report on state-specific variant proportions, 82.4% of recent SARS-CoV-2 samples sequenced in the U.S. region covering Florida were attributable to the Omicron variant.
We have estimated the initial appearance of the Delta variant as June 10, 2021. There are reports that the variant was in fact detected by late May. If we translated the time axis for Delta to the right, however, the Omicron-related hospitalization curve would be running even further ahead of its predecessor.
The calculations in the figure are derived from COVID-19 Reported Patient Impact and Hospital Capacity by State Timeseries, maintained by the U.S. Department of Health and Human Services. The daily counts represent the daily sums of two variables for all Florida hospitals combined:
- previous_day_admission_adult_covid_confirmed: Number of patients who were admitted to an adult inpatient bed on the previous calendar day who had confirmed COVID-19 at the time of admission in this state
- previous_day_admission_pediatric_covid_confirmed: Number of pediatric patients who were admitted to an inpatient bed, including NICU, PICU, newborn, and nursery, on the previous calendar day who had confirmed COVID-19 at the time of admission in this state
Some commentators have expressed a general concern that COVID-19 hospitalization counts include patients admitted for unrelated reasons who incidentally tested positive. Since confirmation of a COVID-19 diagnosis is made by PCR test results that are not immediately available at the time of admission, it is unlikely that the calculations in our figure above suffer from such a potential bias.
If hospitals were backdating COVID-19 diagnoses to the date of admission once they received one- or two-day delayed PCR results, we would detect significant backdating through comparison of serially posted databases. During the past 10 days, we estimate that such backdating accounted for less than 4 percent of all admissions.