Know your probability of getting infected when you come in contact with a Corona infected

When a person gets infected he becomes capable to infect others from the next day. 

But he starts infecting others after 4 -5 days when he starts sneezing and coughing.

 On 8th day he gets hospitalized. 

So from 4 th day to 8th day he spreads infection.

So every patient spreads infection for 4 days.

 How many persons get infected from him? On an average? In India? No data

 Can this data be extracted out of the daily C-19 data?

 Let’s try ! But wait! 

What is the use of knowing this ? Let me tell you! 

If you divide the number of infected persons by the total number of contacted persons, you will come to know the probability of your infection when you come in contact with an infected person. 

Not clear?

Let me elaborate with an example : 

If one infected person is meeting 5 persons everyday he will meet total 7x5=35 persons till he reached hospital on his 8th day of getting infected. Now if he has infected 3 persons during his infection period of 7 days, it means that 3 out of 35 contacted persons have got infected. So the probability of one’s getting infected after coming in contact with an infected person is 3/35x100 % ie about 8.6%.( instead of 99% which we generally assume). 

Now let’s find out this percentage 

The starting point is my earlier blog in which I had explained the following 

The present average daily rate of increase of total number of cases in India is 3.57%.

 With this rate the growth of number of cases takes place as follows : 

 So 28 infected persons whose infection was 1 to 7 day old who were hidden, are exposed  by 7th day.

It means if total no of know cases in a town is 100 , there are 28 hidden cases on the same day which may be 1 to 7 day old. 

So on day 1 there are 27.83= say 28 infectors. 

They are in the process of infecting others due to which the number of cases are increasing. 

But every infector will not get 7 days opportunity to spread infection.

Those who are 1 day old to 3 days old will get 5 days time.

Those who are 4 days old will get 4 days time.

 Those who are 5 days old will get 3 days 

.Those who are 6 days and 7 day old would get 2 days and 1 day respectively. 

How many persons are how much old infection, is not known.

But since most cases are recent and fewer cases are older, we go ahead with the following distribution of the 28 infectors 

 So when there are 100 cases in a city, we have  a potential of 120 man days available for spreading infection, over a period of 7 days. 

After 7 days, as we already know,the net effect of these 120 man days of infection is a growth of 28 new patients. 

So if you come in contact with 1 infected patient on 1 day,your probability of getting infected is 28/120*100%= 23.33% 

Also if 1 infected patient has met 10 people there is a chance of infection of 2 to 3 persons.

 Is this analysis convincing? Is this information useful? Do tell me!