Will Coronavirus infections reach 800,000 in mid March and 100 million by the end of April???

Many people think the figures released by China for the spread of Coronavirus are low.
I have developed a simple spreadsheet projecting the spread of Coronavirus (2019-nCoV). Like others we assume the disease started spreading in mid November 2019.

Also see my next post:

We assume an incubation period of 6 days (stats suggest a mean incubation period of 6.4 days). The spreadsheet therefore shows six day periods. We also assume that people suspected of being infected once detected will be quarantined with other similar people.

This means that the next newly-infected value (number of new cases 6 days later) is the previous newly-infected value (previous number of new cases) multiplied by the constant factor (Re or Ro, depending on whether new cases are kept in isolation).

How can a Coronavirus out-spread from 5 to 368 people in 5 Cycles (Credit: The New York Times)? If 5 people with new coronavirus can impact 2.6 others, then 5 people could be sick after 1 Cycle, 18 people after 2 Cycles, 52 people after 3 Cycles and so on. See:



The spreadsheet produced the same results using Ro = 2.6


We assume that each person infected may infect an average of 1.8 other people before being isolated from the general public. i.e. Re = 1.8

The factor 1.8 was chosen since it appears to generate infections similar to the February figures here:

We would expect the 2019 figures to be low in the data since isolation appears not to occur before the end of December. i.e. Ro = 2.6 (i.e. no isolation) may be more appropriate for 2019. However this would mean at least 6500 infections in 2019.

The new number of infected people is the previous number of newly-infected people times 1.8 (Re = 1.8).

Note: Originally Re = 1.7705 was used to generate an approximation to the reported figures.

Using Re = 1.8, by March 11 the total number of infections may reach close to 800,000
Using Re = 1.7705 on the same date the number may be about 600,000
(This number only lags behind the Re = 1.8 figure by about three days anyway on March 11 so the 800,000 will be likely still to be reached mid-March).

Here is the graph for the simulation up to 11 March 2020 [Re = 1.8]:


The graphs below are versions of the above graph.

Up to Feb 28:


Up to Feb 22:


Up to Feb 16:


Below is data from the spreadsheet:


Note the figures above for the rest of March!

We also looked at having three Levels, L1, L2, and L3 with L1=0.5, L2=0.25,  L3=0.25 (with the three Levels applied diagonally over three cycles), and Ro = 2.6
(e.g. On 11 March, 399,589.37 = 281,744.17 + 76,405.15 + 41,440.05)

On 11 March, total infections reached almost 875,000 (873,172.92).


Note the figures above for the rest of March!

Here is the graph for the simulation up to 11 March 2020 (3 levels/cycles, Ro = 2.6)


Here are both sets of data side by side:


Having three levels gives us the opportunity to get better results.

Arbitrarily let’s choose Re = 2.0
i.e. L1 + L2 + L3 = 2

Consider the table below:


These results still give a total for 11/3/20 of over 770,000 cases.
At the end of December there are now only 625 cases.
On 16/2/2020 there are 72,205 cases.
Once again the early results for early February are lower than the reported figures so 800,000 cases are still likely on 11 March, 15 million cases a month later on 10 April, and about 90 million (88,560,440.54) by the end of April. Earlier spreadsheets have this figure over 100 million.

Here is the graph (Re = 2.0) up to 11 March 2020:


Alan Grace
17 February 2020

Also see:

A Sussex man inadvertently infected at least 11 people after contracting the disease at a business conference in Singapore.

The mean incubation period was estimated to be 6.4 days. The incubation period ranges from 2.1 to 11.1 days. The upper limit of 11.1 days could be considered conservative.[10]







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