## COVID Odyssey: Winter Windup 16 ~ Methods used to estimate Ro

Originally posted on Green Bottles, Alan's Ark & COVID Odyssey: Alan Grace's vir[tu]al journey:
In this post we shall look at ways experts analyse the spread of COVID-19. My own mathematical techniques are simple but have produced some surprising results. Analysis can quite often involve solving systems of differential equations (see…

## COVID Odyssey: Winter Warning NZ 9 ~ C = ar^d ~ A trivial way to estimate total case numbers

We have used the formula C = ar^d to estimate case numbers in New Zealand. The easiest was to calculate C is to start with the value a, and on each successive day multiply the previous day’s estimate by r. In last years initial outbreak we saw in New Zealand r = 1.4 and r…

## COVID Odyssey: Winter Warning NZ 8 ~ 2021 Delta midpoint ~ Are we there yet?

We hope we are near the midpoint for the current COVID-19 outbreak (Delta variant) in New Zealand. We had around 82 cases yesterday (29 August) and the previous day. We hope that the number of new cases will start to decline very soon and that there will only be one peak. In the original 2020…

## COVID Odyssey: Winter Warning NZ 7 ~ Will we have 100 cases today? ~ 1000 total by Wednesday?

COVID-19 case numbers continue to rise in New Zealand. We hope that case numbers will peak very soon. We had 82 cases yesterday. Case numbers can be estimated using the formula C(d) = 1.16 x SQRT(2)^d where ^ means ‘to the power of’ and d is the number of days from 10 August 2021. We modify this…

## COVID Odyssey: Winter Warning NZ 6 ~ Estimating the number of 2021 Cases ~ A simpler formula

We have developed a simpler formula for estimating the number of cases in New Zealand for the current COVID-19 Delta variant outbreak.. Our formula is: C = r^d where r = 1.429 and d = the number of days since 10 August 2021. Here is the PDF version: NZCases2021r The effective reproduction rate (Re) is…

## COVID Odyssey: Winter Warning NZ 5 ~ Estimating the number of 2021 Cases ~ Where will the midpoint be?

We revisit the spread of COVID-19 in New Zealand in early 2020. The object is to apply the exercise below to the current 2021 Delta outbreak in New Zealand. If you have not done this exercise, please do it now: COVID Odyssey: Winter Warning NZ 3 ~ Estimating the number of 2020 Cases ~ Where…

## COVID Odyssey: Winter Warning NZ 4 ~ Delta variant 2021 ~ Case numbers appear exponential Dr Bloomfield

New Zealand COVID-19 (Delta variant) Case numbers are exponential. From today’s NZ Herald (26 August page A4): Case numbers can be estimated using the formula C = 1.16 x SQRT(2)^d where ^ means ‘to the power of’ and d is the number of days from 10 August 2021. We estimate the total number of cases…

## COVID Odyssey: Winter Warning NZ 3 ~ Estimating the number of 2020 Cases ~ Where is the midpoint?

We revisit the spread of COVID-19 in New Zealand in early 2020. The object is to apply the exercise below to the current 2021 Delta outbreak in New Zealand. To estimate the total number of cases, we first have to consider when we may have reached the midpoint. Even if the midpoint is assessed accurately,…

## COVID Odyssey: Winter Warning NZ 2 ~ Delta variant ~ Lockdown 4 appears to be working

Lockdown Level 4 appears now to be starting to bring down the daily rate of increase (r) of case numbers of COVID-19 in New Zealand. Update: See: COVID Odyssey: Winter Warning NZ 6 ~ Estimating the number of 2021 Cases ~ A simpler formula ee the last column in the table below where values for…

## COVID Odyssey: Winter Warning NZ ~ Delta variant ~ May one person infect 12 others?

Based on NZ current case numbers for the Delta variant, we estimate on average one person may infect at least 12 others (Ro > 12) without quarantine or isolation. Case numbers may close to triple over a two-day period (1.7 x 1.7 = 2.89). For the Delta variant worldwide, we have estimated Ro to be…

## COVID Odyssey: Winter Windup 15 ~ Executive summary ~ Our formula for Ro

Updates for New Zealand Delta variant data and results see: Welcome COVID Odyssey: Winter Warning NZ 6 ~ Estimating the number of 2021 Cases ~ A simpler formula COVID Odyssey: Winter Warning NZ 2 ~ Delta variant ~ Lockdown 4 appears to be working For COVID-19 in the original 2020 outbreak, we have estimated Ro…

## COVID Odyssey: Winter Windup 14 ~ COVID-19 ~ Simulations to develop our formula for Ro

We have used simulations to develop our formula for Ro which is based on the daily rate of increase, r, for cases. For simulations using r = 1.4 and r = SQRT(2), for each simulation we generate 40 outbreaks using Excel and calculate statistics. Sample runs are included in this post. Our formula for Ro…

## COVID Odyssey: Worldwide Winter Windup 4 ~ Is Ro 6 to 7.8 in early 2020?

For COVID-19 in early 2020, we have estimated Ro to be in the range 6 to 7.8. For the Delta variant we have estimated Ro to be in the range 9 to 12.7. Update. See: COVID Odyssey: Worldwide Winter Windup 5 ~ Revised estimates for Re worldwide We consider widening our range estimate for COVID-19…

## COVID Odyssey: Winter Windup 13 ~ Is the COVID-19 Delta variant as infectious as measles?

Experts think the COVID-19 Delta variant is much more contagious than the flu and chickenpox, and on par with the measles. See: https://www.healthline.com/health-news/cdc-says-delta-variant-as-infectious-as-chickenpox-what-to-know-now We have found that Ro for the Delta variant is between 9 and 12.7. See: COVID Odyssey: Winter Windup 9 ~ COVID- 19 Delta Variant 2021 ~ Is Ro in the range…

## COVID Odyssey: Worldwide Winter Windup 3 ~ COVID-19 in 2020 vs 2021 ~ Cases per million people

We look at cases per million people for the 31 countries with over one million cases on 6 August 2021 and compare the results estimated for the daily rate of increase, r, estimated a year earlier on 6 August 2020. We have looked at the spread of COVID-19 throughout the world early in 2020. We…

## COVID Odyssey: Get your jabs ~ I got my second jab this morning!

Originally posted on Green Bottles, Alan's Ark & COVID Odyssey: Alan Grace's vir[tu]al journey:
Get your jabs There are those that would extinguish The light that God has made And interrupt our journey And all the plans we laid There are those that would take our spirit And make us feel…

## COVID Odyssey: Worldwide Winter Windup 2~ Be afraid, be very afraid of the Lambda variant

Be afraid, be very afraid of the Lambda variant. Strong likelihood of more dangerous COVID-19 variants – WHO. The eighth meeting of the Emergency Committee convened by the WHO Director-General under the International Health Regulations (2005) (IHR) regarding the coronavirus disease (COVID-19) took place on Wednesday, 14 July 2021 from 11:30 to 16:00 Geneva time…

## COVID Odyssey: Get your jabs

Get your jabs There are those that would extinguish The light that God has made And interrupt our journey And all the plans we laid There are those that would take our spirit And make us feel such pain To wash away the progress And years of hopes and gain We must all stand united…

## COVID Odyssey: Worldwide Winter Windup ~ COVID-19 in 2020 vs 2021 ~ How many people may one person infect in your country?

We look again at the spread of COVID-19 throughout the world early in 2020. We look at case numbers up to 6 August 2020. As expected estimates for Re#2 (last column in the first table, calculated using our formula for Ro below), and hence Ro occurred very early in an outbreak in each country. Ro…

## COVID Odyssey: Winter Windup 12 ~ Conclusion~ Ro = 6 to 7.8 in early 2020?

We revisit data for the spread of COVID-19 in early 2020. We see in China that a daily increase close to r~ 1.5 fits the case data well from 23 Jan to 28 January 2020. We have seen in New Zealand that a daily increase close to r~ 1.4 fits the case data well from…

## COVID Odyssey: Winter Windup 11 ~ COVID-19 ~ Daily decline in infectivity

We have assumed that case numbers increase at a daily rate of r and infectivity decreases daily at a rate of 1/r. This simplifies the formula. However it is possible that infectivity decreases daily at a different rate. Below is a graph showing various rates: Below is data for the graph. Note: values have been…