https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(20)31482-3/fulltext
This Lancet study has some strong words for the concept of herd immunity, while bringing up several points many of us here have stated previously. Antibody levels in asymptomatic patients fade quickly — and estimated immunity length in a population is estimated to be somewhere in between a few months to a couple of years.
“In light of these findings, any proposed approach to achieve herd immunity through natural infection is not only highly unethical, but also unachievable. ”
And I guess they read the KI study and came to the same conclusion that I did.
“A subset of asymptomatic SARS-CoV-2 cases shows a lower antibody response and titres that wane quickly. It is unknown whether these patients are protected by other immune functions, such as cellular immunity. In summary, such individuals would not be detected by serological assays but might confound the true exposure rate.”