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Mitigation Strategies: Decision making model, March 2022
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Background: As requested by the MCPS Trustees, the COVID task force has discussed a set of metrics that could be used to make decisions regarding the COVID mitigation strategies, specifically the face covering guidelines.  These metrics were discussed by the MCPS Trustees at the November meeting.  Below represents the final decisions made by the MCPS Trustees.        Updated March 12, 2022

Simplified Decision Making Model:

MCPS will modify the COVID mitigation strategies (including face coverings) when:

Indicator

Goal

Current status

Goal and Data Trend

#1 Vaccine: availability and time given for full immunity for 5-11 y/o

COVID Vaccine is widely available and time has been given to reach immunity for 5-11 y/o, approx 8 weeks after first shots made available in Missoula County.

Shots made available by MCCHD on November 8

Goal met on January 2

AND   ALL three of the following conditions have been met.  (Note: These indicators could be met concurrently during the 8-week waiting period associated with indicator #1.)

Indicator

Goal

Current status

Goal and Data Trend

#2 Incident Rate:

Daily new cases of COVID 19, per 100K Missoula residents, 7-day average.

< or equal to 20 for 14 consecutive days

As of March 11, the county IR was 12

Goal met on March 12

#3 MCPS New Cases: The total number of new cases per week, total over 7 days, tallied each Friday.

< or equal to 30 for three out of four consecutive weeks, when school is in session.

30 would represent approx 0.3% of total population and an average of less than 5 new cases per day.

New cases week ending

Feb 25 = 19

March 4 = 11

March 11= 15

Goal met on March 11

#4 MCPS Close Contacts: The total number of students or staff determined to be a close contact to a confirmed COVID case, total over 7 days, tallied each Friday.

< or equal to 125 for three out of four consecutive weeks, when school is in session.

125 would represent approx 1.2% of total population and an average of less than 18 close contacts per day.

Close Contacts week ending Feb 25 = 57

March 4 = 27

March 11= 42

Goal met on March 11

As decided at the November 9 Board meeting, once these conditions are met, the MCPS Board has given permission for the mitigation strategies (specifically the face covering guidelines) to be modified.  It was also decided at the November meeting, that the face coverings should be reinstated when any 1 of the 4 conditions is no longer met.

Rationale: How did we determine “goals?”

  1. COVID vaccine available, 5-11 year olds, 8 weeks after first dose available in Missoula
  1. There will be accessibility issues when released - due to demand. We assume about 2 - 3 weeks before it is widely available to anyone that wants one.
  2. The vaccine requires 5 weeks from the first dose before full immunity.  First dose + 3 weeks, then second dose + 2 weeks before immunity.
  1. Incident rate of 20 or less (As measured on MCCHD Data Page.)
  1. Last spring, MCCHD used 25 as the goal, coupled with a 60% vaccination rate as triggers for changes to masking.  While the goal of 25 was met at the end of January, the mask requirements were not lifted until May 10 after the county reached the 60% vaccination rate.
  2. 25 is still considered “high transmission” by the MCCHD and the CDC.
  3. As we are not using vaccination rate in our decision making metrics, we chose a lower Incident Rate.
  1. MCPS Weekly new cases of 30 or less (As recorded on MCPS Summary Sheet)
  1. We know that the Delta Variant has resulted in higher case counts, especially among children. Comparing our current surge to last year’s highest surge, we calculated a 155% increase in the number of positive cases tallied over 7 days.
  2. Using this % increase, we adjusted last year’s case counts. During the period of increase last year (Oct - Nov) the adjusted average number of MCPS cases per week was 47.0.  During the period of decline last year (Jan - March) the adjusted average number of MCPS cases per week was 23.0.
  3. Given these two averages, 35 was the median. However, 30 is closer to the average number of cases during the period of decline.
  1. MCPS Weekly number of students or staff considered close contacts, 125 or less. (As recorded on the MCPS Summary Sheet.)
  1. We know that the Delta Variant has resulted in higher numbers of close contacts. Comparing our current surge to last year’s highest surge, we calculated a 59% increase in the number of close contacts tallied over 7 days.
  2. Using this % increase, we adjusted last year’s case counts. During the period of increase last year (Oct - Nov) the adjusted average number of MCPS close contacts per week was 219. During the period of decrease last year (Feb - April) the adjusted average number of MCPS cases per week was 52.
  3. The median of these two numbers is 135. Based on feedback from the COVID committee, 125 seemed like a reasonable goal and would account for some of the fluctuations that occur based on various student activities.