Figure 1. Santa Fe County: The cumulative number of positive COVID-19 test results is shown by NMDOH reporting date. Overlaying these results are the four exponential functions that we used to fit this data. The green curve is our estimate of the current number of active COVID-19 cases (among individuals that initially tested positive). Also presented are the doubling times computed from the data and from the exponential fit. The doubling times are calculated by using data from the previous day and the following day. Created by Marv Alme
Figure 2. 30 Counties of New Mexico: The cumulative number of positive COVID-19 test results is shown by NMDOH reporting date. The green curve is our estimate of the current number of active COVID-19 cases (among individuals that initially tested positive). Also presented is the doubling times computed from the data. The doubling time was calculated by using data from the previous day and the following day. Created by Marv Alme
By MARV ALME
Los Alamos
A COVID-19 Doubling Time greater than 10 days is a significant threshold, and New Mexico is achieving that except in the northwest corner of the state.
While an enormous tragedy is occurring in the Pueblos and Reservations of Northwest New Mexico, the currently implemented stay-at-home policy appears to be working to reduce new cases of COVID-19 in the remaining 30 counties of the state.
The doubling time exceeded 10 days on April 10, and has remained above 10 days since then. This is significant threshold for controlling the COVID-19 pandemic, because the average New Mexico experience has been that 10 days after testing positive for COVID-19, essentially all individuals have been designated as recovered by the New Mexico Department of Health. (Ref 1) The NMDOH recovered designation means that the individual no longer tests positive for COVID-19, not that the individual has fully recovered from the physical effects of the virus.
To assist in understanding our estimating process, we will first review the Santa Fe County data. Figure 1 above shows the cumulative number of positive COVID-19 test results reported by NMDOH, our simple fit to that data, and the doubling times for the data and the fit. We also show our estimate of the current number of active COVID-19 cases among the individuals who tested positive. This estimate is generated by subtracting the number of positive tests reported 10 or more days ago from the cumulative number of positive tests reported to date. Again, the 10 day recovery period was estimated from the NMDOH reported recoveries. A COVID-19 Doubling Time greater than 10 days is a significant threshold, and New Mexico is achieving that except in the northwest corner of the state.This was done on April 12 at which time the recoveries plus deaths had been growing exponentially for about a week.
We see in Figure 1 above that the doubling time passed 10 days on the 4th or 5th of April. The number of active cases peaks as the doubling time becomes longer than 10 days. The number of new positive tests in Santa Fe County has varied from zero to two from the 6th of April on. The significant variation in the doubling time after April 6 are due to the small sample size and have little meaning.
Now turning to the 30 counties of New Mexico, Figure 2 above shows the cumulative number of positive tests in the 30 counties as well as the total for all of New Mexico. Also shown is the doubling time and our estimate of the number of active COVID-19 cases. The doubling time crossed the 10 day threshold on the 10th of April and has continued to stay above that level. As expected the estimated number of active cases began to decrease on the 10th of April.
We emphasize that these are estimates. They are based on data reported to date. This could change dramatically for the worse if cases are seeded from the northwestern corner of the state. The cumulative number of positive tests in those three counties exceeded the cumulative number of positive test in the remaining 30 counties yesterday, the 17th of April. Today, the 18th, 67 new positive tests were reported in the three counties, 20 new positives in the other 30 counties.
Ref 1. https://ladailypost.comnew-mexico-reported-covid-19-recoveries-track-10-days-after-reported-positive-tests/