Covid-19: The Curve Indeed Has Been Flattened, Says Leading Epidemiologist Dr. Muliyil
There has been a slowing down of the rate at which the epidemic is spreading in the country, says Dr. Jayaprakash Muliyil.
The last time BloombergQuint spoke to Dr. Jayaprakash Muliyil, one of India’s leading epidemiologists, he warned that it would be a very long road to normal.
That was on March 26, just a couple of days after India announced its first 21-day nationwide lockdown due to the Covid-19 pandemic. Large gatherings and celebrations are a thing of the past, he said, at least for the foreseeable future. 21 days is the “minimum possible time” to know if an exponential rise has been altered, he pointed out, at the time estimating the novel coronavirus had a reproduction factor (R0) of 2.8 and that India would need a herd immunity of 55 percent to kill the curve.
Today, 27 days into an extended all-India lockdown and on the first day some additional economic activity has resumed in certain states, Dr. Muliyil offers a more positive prognosis.
“...the curve indeed has been flattened,” he says, based on which he has lowered his assessment of the reproduction factor (how many individuals are infected by one patient) but raised his threshold for herd immunity in the denser parts of India.
To be sure, India continues to add a thousand or more cases every day (1,540 in the last 24 hours), but recoveries have also spiked. Besides, for those new to the phrase - flattening the curve—it’s about using measures such as social distancing and lockdowns to slow the spread of the disease.
Watch | The full interview with Dr. Jayaprakash Muliyil
Edited excerpts.
Have we succeeded in flattening the curve?
That question is very easy to answer. We have. And we have data to show that the curve indeed has been flattened. But the word ‘success’ you have to interpret cautiously, because it will depend on our goals. So to answer your question, yes, it has made a difference in slowing down the transmission of the disease.
What specific data have you relied on to come to the conclusion. Because many people are reading many different cuts of data to arrive at different conclusions. You're the expert.
There is a particular parameter we measure in studying the epidemic and that comes from this basic reproduction number (R0 or R nought). We started with something, but it seems to come down indicating that there is a reduction in the disease transmission. You can make out the same thing by looking at the doubling time. There appears to be a slowing down in the rate at which the epidemic is spreading.
The R0 you spoke of in the last interview was 2.8. As for the doubling rate—the Health Ministry today has claimed that from 3.4 days before the lockdown, India is now taking seven-and-a-half days to double the number of patients. Is that satisfactory? Does that amount to some degree of success?
No. That is not the way to interpret it. We wanted to slow it down to buy time. Why did we want to buy time? To prepare ourselves to face the epidemic.
Because if you try to believe that you can actually get rid of the problems due to virus by locking down and reducing doubling time, that is not true. It will inevitably spread everywhere.
So we have slowed down the rate at which it is spreading, but that is not the solution at all. The solution is completely different. If I recall in during the last interview, I did mention it to you.
Yes, we spoke of herd immunity and I’ll get to that. You just mentioned the the reproduction rate has reduced. Is that what’s giving you comfort?
No, it doesn’t. It’s a description of an epidemic. I think I used a number 2.4, I can’t recall. These are calculated numbers—estimates you make of an average of several data points that you get. So it was ranging around that. It has come down, which means the rate at which the epidemic is spreading has gone down. But that doesn't eradicate the virus. That is the problem.
How much does it come down to according to your calculations?
Quoting other people, it has come down to 1.8, probably 1.7. That is the kind of rate people are talking about. They differ according to the methodology, and according to the way they calculated. But again, it’s a fairly good estimate to indicate there has been a slowing down of the rate at which the epidemic is spreading in the country.
These assessments are all based on current data on patients and tests. The April 19 ICMR data shows India has tested 4,01,586 samples, 3,83,985 individuals and has 17,615 confirmed patients (the number has risen since then). What do these numbers tell you? Are we testing enough? Do we have a long way to go?
The number just tells you how prevalent the virus is. A number like that is like a snapshot, you test some people and in that proportion how many have the illness or the infection? Now remember, majority of the time people who get the Covid-19 virus will be asymptomatic and have absolutely no symptoms. Now we started off by testing only the patients coming with sickness. That gives us an indicator—is there a disease existing here? And we established that. Now the question is how prevalent it is. To realise that it’s a little difficult just by using the test you described. This is the RT-PCR test. What we need to do is to get rapid (antibody) test going. That tells you what proportion of our people have been already been infected by the virus. That is the line. Because we are fighting an enemy who we cannot see and an enemy that moves surreptitiously. So you don’t know where all it has spread. The one way to get it done is (to determine) the IgG (antibodies), which is part of the rapid test. That will give us a clear indication how big the spread has been.
I will come to concerns around rapid testing. Before that, are we testing enough? What more do we need to do to be able to actually capture the reality of this virus and its spread in India?
In my opinion, testing and isolation is okay in the early phase, at least during the containment phase. Not once the disease has become established all over, and we see evidence of that, that it has taken a firm foothold in the country. Now, I'm (talking) from purely the management point of view. These procedures or maneuvers hardly ever create an impact on the spread of the virus. Testing informs you, but testing really doesn't have an impact at the rate at which the disease can spread. That is a difficult notion to invite. It is technically impossible to test and isolate every single infected person and the number of them seems to be large.
So the problem with this disease is that it spreads so fast.
The 75 number—is that just a number you picked to illustrate the widespreadness of this disease?
Recently, there was a study from California, what they did was, they measured the IgG (antobodies) or how many have been infected in the community. Then they compare that with a number of cases that they knew had approached the hospital. And that number told us there are quite a few others who have not had any clinical illness but they are IgG positive, indicating they had been infected. Now 75 is the middle point of the range they suggested. I think they said something like 50 to 80. So, maybe 65 is a better number to use.
The lockdown quite obviously has severe economic consequences. There are those that argue it should be lifted. They cite data such as 4.4 confirmed cases per 100 tests, to suggest a far lower spread than anticipated. Are these accurate ways to understand the spread of the disease according to you?
If you need to test a large number, you have to test sensibly in each state or each district just to get to feel of how much the spread is. There is a systematic way you can study that. The overall number—when it’s low, it’s uncomfortable.
I think we are testing enough. The problem with the testing, the RT-PCR test remains positive, transiently. It is positive, and within a week or 10 days, it becomes negative. I don’t know which test they’re actually using now, because it has a sensitivity problem too.
So I'm saying, I know you're using a general term in terms of test, test-test. I also agree we should test enough. But it if gives you comfort—that we are testing enough, say a million, that doesn't stop the epidemic in anyway. We just know it is spreading, but that we already do. We know there is enough to be anxious about. We know the disease is spread all over and we have to now look at the way we mitigate the whole situation. By that, I mean, prevent deaths. Testing doesn’t prevent deaths.
A lower reproduction rate is one number that you are relying on to assess the effectiveness of India’s measures. What are the other data points that you rely on to show whether India is better or worse off than other countries? People are attributing lower cases to hot weather, BCG vaccine, etc..What are the data points that you find confidence in?
The R0 that we discussed last time, and I don't recall exactly what all we discussed, but that is a point I use to estimate expected herd immunity. For example, influenza had an R0 of 1.7. But it spread much faster because it had a regeneration time, which is measured in hours. So there are different characteristics, which describe the rate of spread, but R0 gives you a kind of estimate at what proportion of the community has to become infected before the epidemic stops on its own.
The last time you told me that you estimated the herd immunity required in India would be 55 percent. Is that still the herd immunity number that you're working with?
No, the herd immunity number has gone up to 60 or 65, and there are more studies coming up. Now remember, this herd immunity is a function of the density of the population—in rural areas it is less dense and the herd immunity and R0 maybe lower and consequently, the proportion to be infected may be less. On the other hand, an area like Dharavi in Mumbai, the density of the population is high. So, it is difficult to understand this as an average value. You have to remember that it kind of shifts in terms of magnitude from area to area. The calculated R0 in the ship Diamond Princess was 14.8. That’s a huge number because they were all locked into one ship. Some of the slum areas have a very high density. On the other hand, in the rural area, the R0 would be so much less. So, you know your question cannot be answered in simple term for a whole India. We work on averages and the actual situation may vary from place to place.
Other data points being looked at to make the argument that maybe the lockdown needs to lift faster—is the death rate. India is at 0.41 per million versus 3.34 in China or 124 in U.S., according to John Hopkins data.
I am not familiar with the number you're quoting. But let me ask you a question. Now, did you hear about the Japanese government saying that they expect four lakh deaths? There was an announcement from the government—four lakh deaths. That is what they are expecting during the epidemic. India’s population is 10 times that of Japan. So how many would you expect to have the same rate?
We also have a younger demographic?
So if we are to go by the younger population, we should be estimating the number of deaths will be 4 million (40 lakh) approximately. But the only bright side is that we have a solution to the problem. The solution to the problem I mentioned earlier is that 80 percent of those will belong to above 60 years of age. So, if you devise a method of isolating them somehow then the whole mortality rate will fall. I cannot see any other way of reducing the burden of mortality due to this virus in India.
Lots of people argue that we aren't seeing a flood of cases in hospitals. There is no anecdotal evidence to suggest city hospitals, urban health centres are being overrun with sick people. Does that support the hypothesis that India is witnessing a slower spread?
The heart wants to believe what it wants, because I’m scared. So I want to believe that, but my brain doesn’t permit me to go along with that argument at all.
Why is that?
I know what the arguments are.
So I am a bit cautious. I will still prepare for a large number of cases, because when they land up at the doorstep of the hospital, we should not be found wanting.
Do you believe that the additional measures of preparedness that states and the central government have attempted to put in place are sufficient to deal with even this projected case load?
Well, not the total projected case load because the problem is they will all happen very rapidly. But if you are able to keep the elderly out in some way, not all of them would be possible, but at least 75 percent of them, then you will have a 75 percent reduction in the number of people seeking hospital care. So that is what I’m kind of hoping will happen because you’ve seen elsewhere in other parts of the world, how frightening this epidemic can be.
Are you in agreement of lifting the lockdown on May 3? I know this is a really tricky question because of the economic consequences of an on-going lockdown but nonetheless, from a health point of view?
A lockdown is only going to prolong the whole situation and there is no end to it. You may go on for three months, six months; you think we can live on a lockdown for how long? Remember, children get pneumonia, meningitis and their access to healthcare is now limited. Immunisation schedules have been stopped. We may have other outbreaks coming. There is apart from the economic and agricultural trauma we'll have to face. So I’m confident the experts helping the government will see through this and they will make sure that these activities are sustained in future. And, probably social get-togethers and such things should be curtailed for some more time to come. Now I'm not in favour of completely opening up. Certain restrictions have to be there in large crowds gathering, and so on and so forth.
I do recall in our first interview you said that social distancing or physical distancing should now become a way of life for the next year or so, till a cure or medical solution is found to this and that is my last question. There are a ton of efforts going on across the world to find both an effective treatment for this virus as well as a vaccine. Are any of these looking very encouraging to you?
Medicine is very iffy. On the other hand whatever I have read about vaccines looks very plausible. Remember these vaccines are not an issue of whether they will protect. That is not the main question. I think if it will do harm to some people is what we have to clarify. For that it takes a little while before we subject population to mass vaccination programs. The delay is mainly because of the safety issues. I'm more confident and hopeful that there will be a vaccine available, at least within two years.
Is there a particular vaccine effort that looks best to you?
No, I am not an expert on that. There are several vaccines. I cannot comment.