Covid-19 in India: This is just the beginning, be prepared for July to November.
In recent days, from my conversations with friends, colleagues and relatives, I’m getting an impression that most folks are expecting Covid19 to somehow disappear soon. This is my attempt to explain the seriousness of the situation based on some approximate calculations. Unless we are extremely lucky and miraculously nature (temperature, humidity, weather, seasons etc) kills the virus we need to be prepared for coming months.
There are only two logical end points to this crisis. One is every one gets vaccinated. Second is enough population (~80%) gets infected and acquire heard immunity as a country. Ideally, everyone getting vaccinated is the best option. But the expected time frame for enough doses to be manufactured and distributed for 7.8 Billion people is 9–12 months in the best case scenario, if everything goes right. It definitely will not happen in less than 6 months. Till that happens, the contagion keeps spreading and lock-downs will hopefully slow the spread.
Below is simple back of the envelope calculation on the dynamics of the spread in India:
India population ~130 cr
On May 6 doubling time (number of days taken for cases to double) is 12 days
On May 6 number of cases in India is 53K
So, factor of increase for all population to be infected =
130 crore/53000 = 24528
Approximating to doubling time: 2¹⁴=16384
53ooo*16384=86 crores (67% of population)
So it takes 14 doubling times till the 67% population is infected.
Below is the total time it takes for 67% of the population (86 crores) to be infected under various doubling times:
If doubling time is 5 days : 70 days (2.5 months)
If doubling time is 7 days : 98 days (3 months)
If doubling time is 10 days : 140 days (5 months)
If doubling time is 15 days : 210 days (7 months)
If doubling time is 30 days : 420 days (14 months)
Even with 1.5 month lock-down, the current doubling time is ~12 days. If the lock-down is relaxed, the doubling time will only decrease. So a reasonable expectation on bounds of doubling time can be between 7 to 15 days.
That means next 2 to 6 months (July to November) are crucial where the contagion will be present in a large percentage of population. And people should be prepared for this July to November period. Especially elders. Be prepared with enough supplies of medicines and essentials. Be prepared to not venture outside and completely remain indoors during these months.
To simplify the above calculation: On March 23 India had 500 cases and in 1.5 months they became ~50,000, that is 100 times increase during lock-down period. If the spread continues at the same rate, in the next 1.5 months by June end, 50,000 will become 5 Lakhs (50000 x 100) and 50 crore (50 Lakhs x 100) by August 15. This is the seriousness of the situation.
Bottom line: With or without lock-downs July to November is crucial period where the virus will be present in a large percentage of population. People, especially elders should be prepared to completely remain indoors and have enough essential supplies and medicines during these months. Get any essential medical procedures done in the next few weeks. This is not over.
On a positive note: Fortunately ~80% of Indian population is below 50 years. India can achieve heard immunity protecting our elderly even if the vaccine is delayed and lock-downs are relaxed a bit.
Caveats: There are a few important factors I ignored in the calculations that may vary the timeline of spread.
One is the actual number of current infections could be higher by a factor of ~5 because of asymptomatic nature of Covid19.
Second important factor is there is no clear evidence yet of re-infection not occurring. Heard immunity works only if the infected develops immunity at least for 6–12 months. If re-infection happens then acquired heard immunity goes for a toss and vaccine is the only option.
Third is that the doubling of infections won’t happen uniformly throughout regions and time periods. So this is only an approximation. Some regions may become highly infectious in late June and some regions could be very safe till next year.
I have also not considered the effect of therapeutics, as they only limit the seriousness of outcome once infected and probably can decrease the rate of spread but won’t stop the contagion.
