The human society as a whole is reeling under the impact of the Covid 19 viral pandemic. Ever since SARS Cov 2 virus spread from Wuhan in China to other parts of the world, it has changed the way we live. Thousands have lost their lives while millions lost their jobs and a huge number of businesses had do shut down.
The most important question that looms in everyone’s mind nowadays is when will it end?
Nobody can be sure about when and how this pandemic will end. However, based on historical experiences of previous pandemics and taking into consideration the special characteristics of SARS Cov 2 virus, one can try to predict its future trajectory and eventual end.
There are mainly three ways by which a pandemic like this can end. Two of them come from human effort while the third one will happen without any effort. Many a time a pandemic ends with the help of all the three ways.
The three ways are 1) Halting by containment 2) Halting by immunity through vaccines and 3 ) Natural end by getting immunity through infection.
Halting by Containment
Breaking the chain of transmission is the strategy used in halting by containment. The virus is not allowed to get inside a susceptible host. A great deal of personal and public effort is needed for such a strategy to succeed.
Personal efforts include maintaining physical distance, wearing masks and other protective equipment’s , quarantining yourself when you are sick, etc.
The Government efforts in this containment strategy mainly include banning public gatherings, implementing lockdowns , early testing of sick people, tracing contacts of infected patients and testing and quarantining them.
SARS Cov 2 is a Coronavirus and is closely related to SARS Cov which caused the SARS epidemic in 2003. and MERS Cov which resulted in the MERS epidemic in 2012. Both SARS and MERS was halted by this strategy. Countries like China and South Korea was able to stop almost all local transmission of Covid 19 using many of these steps.
But most other countries in the World were not able to contain SARS Cov 2 transmission by this way. Even in Korea and China, new clusters of local transmission of Covid 19 have been reported in recent days. The main reason for this is the high percentage of transmission of Covid19 virus by asymptomatic but infected people. In both SARS and MERS, the transmission of the virus occurred only after symptom onset and peaked during the very sick period when the patient is already diagnosed and is in the hospital. At that stage containment was easy.
Now it’s fairly clear that the containment method can only help in reducing transmission and deaths. It cannot halt the Covid 19 pandemic.
Halting by gaining immunity
If containment is not halting the pandemic we have to think about the other two ways. Both depend on the ability of the human body to develop a robust immune response against SARS Cov 2 infection. Both natural infection and Vaccines can
generate an immune response. When a sufficiently large percentage of people in a community develops immunity the epidemic is halted because an infected person becomes a dead end for the virus as she is surrounded by immune people. Thus even those who do not have immunity are protected as a result of being a
member of the herd. This is called Herd protection or Herd immunity.
But does Covid 19 infection provide good immunity so as to
prevent re-infection ?
Though there are some media reports of re-infection, scientific analysis of the data that we have so far shows that re-infection is extremely unlikely for at least several months to a year or two.
So both the gaining of immunity by vaccination and that by natural infection should, in the long run, halt the pandemic. The 1918 influenza pandemic ended as most people got infected and became immune.
But doing nothing and allowing everyone to get infected can have disastrous consequences. It can result in overwhelming the health care system and there may be deaths in millions. Deaths may occur not only due to Covid but also due to other illnesses not managed well by a broken health system.
Thus the only working options before us is halting the pandemic by either containment or vaccination. We still do not have a vaccine. It may take 12- 18 months before an effective vaccine is widely available. Until then we can only
contain the virus by trying to reduce transmission as much as possible using the Test-Trace-Isolate method.
Finally, how will the pandemic end ?
When it finally ends I am sure all the three ways of halting the pandemic would have played a part. The presence of large number of previously infected people will halt the transmission in some areas. Vaccines will halt transmission in places where a large percentage are immunized with it. Clusters of transmission may still, break out in some places and will be managed by containment measures and further vaccinations.
When will it end ?
The widely available and efficient vaccine is a must for halting the epidemic. The most optimistic prediction says it may take 12 months. So we can assume that the Covid 19 pandemic will end in the summer of 2021.
Does it mean that the infection rates will continue to escalate unabated for one more year ?
No. Effective containment measures can, by and large, reduce the speed of the pandemic. Even in Western Europe with just around 5% of the population infected it is on a steep decline. The presence of a large number of people who are infected in a population can reduce transmission. Also, Summer weather may play a part. In coming Winter transmission may explode again. In the next 12 months, we can
expect to see waxing and waning of infection rates in different parts of the World depending on many variables.
As of now, we have to continue containment measures that are rational but not too lethal for the population. Instead of a nationwide lockdown, each State, City, and District should try containment at hot spots of transmission. We have to continue the Test-Trace-Isolate policy in a very efficient and economical way.
Finally, we have to do everything possible to speed up the arrival of a safe and effective vaccines which will finally halt the epidemic by next summer.
This article of mine was earlier published in Kochi Post.
I think this is a good and valid summary article. Thanks for posting it here.
It is unfortunate that some right-wing governments (such as Trump in the USA) seem to talk boldly on other topics, yet seem to just give up as far as containment. In the USA, I think we will have pockets of containment where there are sensible leaders, but our R0 and spread will not decline much until a couple of months after a new government is sworn in, if ever.
India had a shut down too early without much facilities for testing. Then we had to relax as people began to die of hunger.
Sometime in Jan 2020 I had come across this blog which explains SIR/SIS models using interactive simulations:
https://www.meltingasphalt.com/interactive/going-critical/