COVID19 update, Shavuot edition: Singapore research finds 50% of sample has pre-existing immunity

Breaking news (via Instapundit): Prof. Francois Balloux from UCLondon highlights preprint from Singapore:

Recent preprint reporting that 24/24 (100%) people form Singapore infected by SARS-1 in 2003 have pre-existing T-cell immunity against #SARSCoV2, but more surprisingly 9/18 (50%) with no exposure to SARS-1 also possess T-cells targeting #SARSCoV2.

One take[-]home message is that infection with coronaviruses induces strong and long-lasting T-cell (cross-)immunity. T-cell immunity is likely a far more important for our immune response to #SARSCoV2 infection than antibodies, in line with other recent reports.

What remains unresolved is which virus caused T-cell immunity in the people with no prior exposure to SARS-1 in 2003. We know of seven coronaviruses infecting humans: #SARSCoV2, SARS-1, MERS and four causing ‘common colds’ (OC43, HKU1, 229E and NL63). [NB: most common colds are caused by rhinoviruses, which are a different family]

Intriguingly, none of the known viruses in circulation in humans looks like a good candidate for the T-cell immunity to #SARSCoV2 in those with no prior exposure to SARS-1. This might suggest that other yet unknown coronaviruses could have been in circulation in humans.

No surprise that having had SARS 1.0 would protect you against SARS 2.0, but nice to know. But that half of a random sample would have immunity owing to previous exposure to a common cold-level virus… If confirmed on a larger sample, this could be yuge. Put this together with the 2nd-order correction for the herd immunity threshold, and acquiring herd immunity could take a lot less doing than previously assumed…


Happy Shavuot to my fellow Jews!

UPDATE 1: Dr. Anthony Fauci no longer considers 2nd wave inevitable.

“We don’t have to accept that as an inevitability. Particularly[…] when people start thinking about the fall. I want people to really appreciate that, it could happen, but it is not inevitable.”