COVID Odyssey: NZ New Year Fear 18 Post #945~ COVID-19: Verifying ranges for Ro

We use the table developed in our previous posts to verify ranges for Ro for a number of variants.

We have developed this chart:

COVID Odyssey: NZ New Year Fear 33 Post #960~ NZ OMICRON: Is Omicron as infectious as the measles?

COVID Odyssey: NZ New Year Fear 19 Post #946~ COVID-19 Variants: New Ro estimates

Also see:

COVID Odyssey: Summer Surprise 2 ~ Post#924: NZ COVID-19~ OMICRON has reached NZ border

We use the table below to verify the above chart:

Original Variant early 2020. Range for Ro: 5 to 8 people

In New Zealand for this variant, r = 1.4.

This gives from the table Re = 5.8 and Ro = 7.1,

This is in the middle of the range in the chart.

Cases may double within a two day period.

Delta variant range 9 to 12.75

When Re = 9, r ~ 1.57 and Ro ~ 11.6.

This is within the range in the chart.

Historically 12.75 was chosen for the upper value in the range because this allowed for the possibility for case numbers to triple over a two day period.

For this to happen Ro would now need to be 16.6 and r = 1.732 [SQRT(3)].

At least for r = SQRT(3), Re ~ 12.73.

Omicron variant range approx 11 to 14.5

When Re = 11, r = 1.66 and Ro = 14.3.

Both vales are within the range.

Conclusion

The table gives values within the ranges required.

However to allow for the possibility that case numbers may triple over a two day period, we would need r = SQRT(3) [ r = 1.732] and hence Re = 12.73 and Ro = 16.7.

We will consider this and may re-evaluate ranges in another post.

In the interim we stay with our current ranges.

At least Re  = 12.73 corresponds to r = SQRT(3) and is within the range for Delta and Omicron in the chart.

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