During this COVID-19 pandemic, all eyes are on the number of people infected by the virus. That is important information, but the numbers given is only the number of confirmed cases (meaning, the number of cases among the people who are tested.) There may be (or rather, will be) people infected by the virus who haven’t been tested at all. Since we can’t be sure what the real number of cases is, it is very important to look at other parameters as well. The number of people tested is one thing that is very important to know.
*The “Prepared” parameter is defined based on when the state started finding cases. Adjustments are made for states which wouldn’t have got (unknown) cases earlier.
** Test Positivity Rate: The percentage of positive cases among the people tested
As can be seen, there is a tendency for states which are testing more to have a higher number of confirmed cases. This shows that many other states are likely to have many unknown cases. If the number of tests is low, and yet the cases are high, then it is dangerous. So it is important to know what percentage of people tested were positive. This figure is known as the Test Positivity Rate (TPR).
States which prepared earlier will not miss out on so many cases. As they test, they get more of an idea of where to test. If a state has initially done very little testing, and then one day tests a lot, they won’t have an idea of where to do the tests. So in spite of doing a lot of testing, they will not find many cases. So it is important to know when the state got prepared. One example is with the Koyambedu market in Tamil Nadu. At the end of May, this market had become a COVID-19 hotspot. Tamil Nadu was doing aggressive testing at that time. So, the government immediately noticed the pattern and tested everyone who had been to the market. Roughly 3,000 tests were positive. This was a major hotspot (even for Andhra Pradesh). And yet, if the government had not been doing aggressive testing at that time, they may not have found out that Koyambedu market was a hotspot. Had the government not been testing aggressively at that time, almost all those cases would have been undetected. And it would have spread so much that they might not have trace the cases back to Koyambedu market.
If the number of known cases is high, it can still be contained. If the number of unknown cases is high, that number will rapidly keep increasing.
The following table has the states divided into 5 categories (Ultra Aggressive Testers, Aggressive Testers etc.).
* The testing category for states is defined using two factors: The number of tests per capita, and how early the state started preparing for the pandemic.
The TPR gives us some idea of the situation. If it is higher, the situation is likely to be more serious. However, there are other reasons for the TPR to be higher. Cities are densely populated, so the virus will spread faster. So when suspected people are tested, there is more chance that they will test positive. So in cities, the TPR will be high even if the government is searching well. It also depends on the government’s relationship with the public. In some states, people will self report if they are likely to be infected. In other states, people won’t come forward until the government tracks them down and takes them. (Just see the contrast between states in handling the Tabligi Jamaat spread The latter kind of states will show a low TPR because the government will test many people not knowing who is the correct one. But these states are actually more serious.
Therefore, it is important to know the death-rate. States which are not being able to do enough testing, generally test only serious cases. If you look at only the serious cases, the death-rate is bound to be higher. The real death-rate is actually very low and largely uniform across states. So this figure tells us which states are only testing serious cases.
*Tests per million
There can be more focus on infrastructure in small states (and UTs), that is why they are on top. However, some of these small states are at the bottom because they don’t have a testing lab. These states need to rely on neighbouring states for testing. Among large states, the ones which have good health systems like Tamil Nadu are front-runners. Andhra Pradesh is exceptionally good because the state government nationalised all hospitals (to take control of the private ones).
Asymptomatic Patients:
Asymptomatic patients are patients who have the virus but don’t show any symptoms. Being asymptomatic is good for the patient. But these patients can still infect others. So if they are not tested, no-one will figure out how the virus spread. A very large percentage (probably over 95%) of the COVID-19 patients are asymptomatic. This figure is important for the same reason as the death-rate: to know whether they are testing enough people, or they are mainly testing serious patients. That can be seen way more accurately using this data, but unfortunately this data is not easily available.
Available data on asymptomatic patients |
State |
Percentage* |
Date |
Source |
Tamil Nadu |
80 |
09/05/2020 |
Asianage |
Maharashtra |
80 |
26/04/2020 |
NDTV |
Karnataka |
76+ |
08/05/2020 |
The Hindu |
*Asymptomatic cases per 100 positive cases.
kvsatcmi
Commented 19 Jun, 2020
Nice work Varun. What you say about Koyambedu is true. Had the govt not been testing aggressively, no way this would have been detected.
You may want to look at indscicov.in for models and other analysis.
KV
Venkatavaradan Vanav
Commented 19 Jun, 2020
Great Analysis