COVID-19 Transmission in India
This is both a happy and sad thing, sad is that the research article is about COVID-19 transmission dynamics. The happy fact is, it is about the disease spread in two Indian States- Tamil Nadu, and Andhra Pradesh. Little scholarly fact emerges from the Indian context, and most of it is news, rumors, and memes.
Chanced upon this paper “epidemiology and transmission dynamics in two Indian states” published in Science-a reputed medical journal. Such studies are more needed, as disease spread and infection happen varies between climate, country, resources, genetic make-up, population density, pre-existing medical conditions. When India and Brazil, who are low-income nations are at 6.39M and 4.85M confirmed cases, you know a study done in Copenhagen would not work in Chennai.
The social distancing of 6 ft works beautifully in population sparse countries like Iceland, Canada, but would not work in Dharavi, Mumbai, Chennai, Delhi, or Bangalore, wherein 6 ft, there are two houses already.
We had less awareness, less access to tests, no known protocols among medical frontline workers since this was a new disease. But with stringent measures, and advertisements, and more awareness among people, disease spread has been slowed and the fatality rate has also been controlled.
Reproduction Number, which is the measure of secondary infections that a primary infected person can infect decreased from 3 to almost 1 in both the states. Contact traced cases were more likely female and young population than their index cases. Contact tracing was done for the index cases, with almost 9 people tested as secondaries. The secondary attack rate or transmission from the identified index case to his/her circle was approximately 11%, implying index is more likely to infect 1 out of 10 people he has been in contact with.
The secondary attack was only at 1% in a hospital or clinic because of a sanitized environment, health-conscious people, and social distancing measures. It jumps to 2.6% in the community and almost 9.5% in a household, which is self-explanatory. Secondary attack spikes to 80% in closed proximity travel for more than 6 hours, more likely an airplane, thus implying viral load is also crucial. If you have been exposed to the virus for less time, even with an index patient, and observed sanitization measures, you are less likely to contract the virus, since the volume of virus transmitted would have been less. This was cited as the primary reason for high fatalities among doctors since they are exposed to a high viral load being in hospitals among patients.
Enhanced transmission in similar age pairs is the highest among children and adults aged more than 65 years. This was the exact reason for banning schools and restraining adults from mingling in social places. Though the overall case-fatality ratio is at 2%, it was only 0.05% among children and 16.6% at higher ages. Why the coronavirus is loving men, was also cited in another article, and it is also being confirmed in the study.
Death risk is higher in older age groups, and more likely to male than females, and difference widens as age progresses, and also high mortality among high-income settings. So it is the rich old male who is at the highest risk than the young poor female. One interesting observation was also made of low incidence cases observed in Dharavi, Mumbai. Officials were worried about a huge caseload given poor sanitation facilities and proximity of households, but it seems their immunity has won them over.
Time to death of COVID-19 patients was the lowest among the world at 6 days and sometimes even 24 hours, with many confirmed only after their death. This could be due to late testing, lack of awareness, in the United States it was at 13 days. Maybe their facilities are advanced and access to ventilators, but that is also dumbed by the fact that Tamil Nadu has the highest number of ventilators in the country. Not to forget the fact that both TN and Andhra have the best primary care medical setup in the nation, with more doctors, nurses, hospitals in both the private and public domain.
As mentioned in previous articles, COVID-19 attacks our immune system in a different way than other viruses, it attacks the house aka our body, and opens the doors/windows. Imagine a thief entering your house and stealing jewels but also leaves the doors open, there would be more looting your entire home before you wake up.
India being the diabetes capital of the world, it is no surprise that the prevalent comorbid condition was diabetes at 45%, sustained hypertension at 36% of them, coronary artery disease(12%) and renal disease at 8%. Diabetes killed people between 50–64 years and liver/renal disease at 18–29 years. This is also common logic, with a lesser instance of diabetes among the younger population. 62% of deaths in India happened to people with one or more existing conditions versus only 22% in the United States. So does it imply, that coronavirus is not the killer but it only accelerates the existing medical condition.
A healthy adult with no existing comorbid conditions is more likely to survive the virus, but a smart adult with sufficient social distancing and sanitation measures surely will survive.
The study also states, that more young people are catching the virus here in India than the United States, and we have a metric just for that. India has one of the youngest populations in the world and could be the reason why Brazil has 145k deaths with 4.85M infected and India has 100k deaths among 6.39M infected. There was a lower incidence of mortality among higher age groups in TN/Andhra due to home delivery of essentials, strict quarantine protocols, lockdown measures, community health worker interactions, safety clinics. The disease incubation period at 4–6 days comes from China, and we do not know for how long does this transmit in an Indian setting and among the Indian population.
The spread is quicker in high transmission settings and does not take 4–6 days. Also when you test a contact as few as 5 days before the virus is fully detectable, you get a negative, and also when there is low viral load in the respiratory tract, you get a negative again which might have been positive. Though we check pre-existing conditions on fatalities, and we know diabetes is the highest, it is not collected among all positive spread infections, we do not know if it accentuated the spread.
We have always triumphed over natural, man-made challenges, and we shall overcome this one as well with more dosage of common-sense.
Citation: https://www.medrxiv.org/content/10.1101/2020.09.16.20194787v1.full.pdf
