Thread by @MsMelChen

This is interesting.

If true, it might explain why there are so few deaths and cases in Cambodia, Thailand, Vietnam, Laos despite many connections to Wuhan.

These countries are next to each other & vary in systems of government, state capacity and

nypost.com/2020/08/15/cov…

in measures taken to address the pandemic. Cambodia for example, didn't go into full lockdown and mask adoption is not widespread.

@tylercowen touched on this Mekong conundrum here: marginalrevolution.com/marginalrevolu…

If that report is true, the reason for these statistics could be that

people in these Asian countries were already protected due to cross-reactivity from being exposed to years of related coronaviruses.

They might be full of antibodies that blocked viral surface proteins and antigen-specific T cells generated when they were exposed to these

same related viruses. Sure co-morbity factors are in play.

A lower obesity rate in Cambodia would lower the death rate but not to zero. Having a younger average age would also lower the death rate but not to zero.

Neither of these would lower the incidence or transmissability so these are not the reasons for ZERO deaths.

Perhaps some regions in the US are already benefitting from HERD IMMUNITY (like NYC) and the whole country will be in the not-to-distant-future,

maybe 6 months just as the Asian countries are now. You can't believe that not even a single active shedder didn't go into Phnom Penh and infect 10 people who infected 10 more each, etc. and make a hotspot.

It seems plausible that they got a few infections (mostly foreigners)

because the people were already protected from cross-immunity, especially if there's evidence of SARS-Cov2-like viruses circulating SINCE 2012!

Faraway places (US, Europe, South America, Mexico, etc) weren't protected from similar viruses that are going around Asia every

year and that's why it spread through those populations and claimed many more deaths. It seems something is protecting the Asian populations.

Social distancing and masks slow the spread but can't kill it off. Only white blood cell-mediated protection can do that.

In theory, when there are no more hosts available for the viruses to successfully inhabit and hijack said host's replication machinery, the virus will die out.

This new paper just published in Cell finds

cell.com/cell/fulltext/…

that SARS-CoV-2-specific memory T-cells will likely prove critical for long-term immune protection against COVID-19.

None of the T cell protected, seronegative patients have been counted in our data.

So if the CDC's death rate is .2% without counting the T cell-protected, the real rate is much lower, close to or below influenza's rate of .14%.

To sum up, there might be some evidence that cross-reactivity of antibodies and T cell-mediated protection as a result of years of

being exposed to related coronaviruses, are keeping cases and deaths in S.E. Asia low. That would mean that they have been protected by herd immunity all along.

There's another possibility that can't be ruled out: the genetic make-up of the population could also play a role.

If this is the case, we would only need to check the large Cambodian populations in Lowell, MA and the Vietnamese in Little Saigon, LA, CA.

In fact , we could check them from anywhere in the US or Europe if they meet two conditions, 1) that they came to the US as infants and

2. that they never went back.

If they are not getting covid, i.e. that their incidence of COVID is in line with people living in Cambodia or Vietnam all this time, there is a genetic component to their protection.

If their incidence of infection and death are more in line with the average American who likewise has stayed in the US for life, their protection would be due to antibody and T cell-mediated cross-reactivity.