The mystery of India's plummeting COVID cases

[Frequentflier]

I know people may not care, but the mystery of India's recovery from COVID is being studied by UK and US scientists as well, for tips on how to manage it here. Interesting article on this. They have left out the closure of borders- even to its own citizens- quarantine, and tests at borders, which I think played a part. www.npr.org/sections/goatsandsoda/2021/02/01/962821038/the-mystery-of-indias-plummeting-covid-19-cases

They only appear to have had one wave of the virus. Our graphs almost flattened our during the first wave. Maybe they’ll have another wave?

Definitely possible, as the article says. But the wave was predicted in winter, and now summer is coming.

Maybe they its evolved into a less deadly form? This would be great news. Also, I believe the developing world hasn't been so badly hit because they don't have loads of very elderly people with multiple chronic illnesses.

Even with border closure it’s interesting

How much would demographics help

India is a very young country as well. Only 6% of Indians are older than 65. More than half the population is under 25. Those who are young are less likely to die of COVID-19 and are more likely to show no symptoms if infected.

Over India's winter time, pollution levels are crazy high - especially in highly populated areas like Delhi.

That can result in many people staying indoors, wearing face coverings to filter out pollution, using air filters more etc. Obviously the ability to do this varies according to resources and many people cannot afford to but I wonder if those behaviours are leading to a reduction in infection possibilities?

If traffic cops are giving out masks (as has been reported) then pollution levels might have encouraged more people to wear them?

Either that or close living quarters meant way, way more people caught it to start with - resulting in higher antibody levels now?

Interesting...

Thank you OP, that's incredibly interesting.

Yes I think the young demographic would have helped too. The median age in India is 25 and I believe that of the UK is 45. The article stresses mask usage but I know from experience that most people aren't wearing masks properly anyway.

Either that or close living quarters meant way, way more people caught it to start with - resulting in higher antibody levels now?
Interesting thread. This was my first thought too

They must have antibody read outs?

I think a few places have been incredibly high in other countries

Although T cell plays a role iirc

Would there be areas, especially the poorer parts where cases/deaths wouldn’t be reported?

It is interesting and I'd be interested in the outcome.

I've often wondered if the reason we drop quite quickly in numbers during lockdown is that natural community immunity has already been reached as we let numbers get so high.

Again though it's just a hypothesis that I'm not sure can be proven as such but we do know London had its highest numbers of people with antibodies recorded in January.

India is a very young country as well. Only 6% of Indians are older than 65. More than half the population is under 25. Those who are young are less likely to die of COVID-19 and are more likely to show no symptoms if infected

Surely this is absolutely key?

www.dnaindia.com/health/report-25-percent-of-indians-have-developed-antibodies-against-covid19-reveals-icmr-serosurvey-indian-council-of-medical-research-2872490

Not sure how accurate this is but says 25% antibodies. With a young population maybe many have T cell immunity

Worldwide cases are starting to plummet as well, are we starting to see a natural decline.

It’s fascinating. I think the younger demographic definitely plays a part. I read another article that said it was beneficial to have lots of mild cases (so no lockdown and allow it to spread in younger population) as the virus does then not mutate to become more serious and it stays mild. I’m not sure if I’ve explained that correctly.

The implication was uhh if you lockdown all the healthy people who would have had a mild case this can cause a worse mutation...

T-cell immunity and robust immune systems will also be playing a part. Outdoors lifestyle? Lots of vitamin D.

Few care homes. You either die or you are in good health, there's not a lot of sustaining elderly with bad dementia & many morbidities going on.

A similar situation can be found in many African countries, and it's still really unclear why cases are lower than expected. On the other hand South America is really suffering again, although many countries share similar characteristics such as a relatively young population.

Regarding the article: one factor to keep in mind is that death records in India are notoriously patchy - from memory only about two thirds of deaths even in urban areas have a cause of death recorded, and in many rural areas records are even more unreliable. Many people also cannot affort healthcare and will not seek medical treatment unless they have no other option. Even taking that into account there is clearly something interesting going on though. My guess it's a combination of several factors, rather than one big one.

@yeOldeTrout

Few care homes. You either die or you are in good health, there's not a lot of sustaining elderly with bad dementia & many morbidities going on.

Good point

Last week, preliminary findings from a fifth serological study of 28,000 people in India's capital showed that 56% of residents already have antibodies, though a final report has not yet been published. The figures were higher in more crowded areas. Last summer, another survey by Mumbai's health department and a government think tank found that 57% of Mumbai slum-dwellers and 16% of people living in other areas had antibodies suggesting prior exposure to the coronavirus.

I think this will be a key reason, with many other factors at play. Immunity (natural or vaccine induced) is one of the factors that reduces the effective R number. You can't transmit the virus to someone who is immune. If 50% of the people you meet are immune, you will infect half the number of people you would have infected if nobody had immunity, in other words, the R number is halved.

It's a bit more complicated than that because infection with SARS-CoV-2 doesn't seem to give sterilising (total) immunity, ie you can be reinfected. However, in the same way that partial immunity from the vaccine reduces transmission, you would expect partial immunity after infection to reduce transmission too.

The problem is we believe immunity wanes over time so when that happens transmission will start to increase again.

This was discussed by Dr John Campbell on his YouTube video a couple of days ago. He believes that it is likely to be a combination of youth, Vitamin D and previous exposure to parasitic diseases which seem to be conferring some kind of cross immunity. He has been flagging the importance of vitamin D supplements as a mitigating factor in Covid for a while and can cite a lot of supporting research.

Yes and in Brazil there is quite a large vitamin D deficiency problem so despite the weather that could explain the discrepancy there..

I find it interesting that we are still focusing on antibodies rather than looking more in to t-cells.

T-cells from SARS have been shown to last 15 years.... so it may not just all be about antibodies and therefore less alarming if they wane over time.

I think testing for t-cells is more expensive though.

@Delatron

I find it interesting that we are still focusing on antibodies rather than looking more in to t-cells.

T-cells from SARS have been shown to last 15 years.... so it may not just all be about antibodies and therefore less alarming if they wane over time.

I think testing for t-cells is more expensive though.

Yes, testing for T cells basically needs a scientist in a lab, extracting them from your blood and then doing some experiments with them which could take a few days. At the moment that is obviously expensive and not doable on a mass population level.

Indians are used to grave diseases and worst viral infection than covid. For them covid is a mild thing and they don't even get tested. I think repeated infections over the years have given them good immunity and a general attitude of 'meh' towards covid.