I'm not splitting hairs at all. The point that infection with one serotype elicits lifelong immunity to that serotype only, is not original antigenic sin (OAS) at all, much less lifelong OAS. To make sure we are discussing the same thing, OAS (to me) refers to the effect that infection with (or vaccination against) one serotype makes it difficult/impossible to obtain any useful immunity to a second serotype. Lifelong, means that this effect is very long-lasting (years). If dengue researchers routinely talk about such, then you should be able to produce one paper that demonstrates it. Certainly Halstead does not although it contains an interesting reference to and discussion of the earlier work by Eisen, suggesting OAS lasting 7 months in rabbits. However, my larger point is this: a strong enough OAS effect to actually blunt vaccine effectiveness is rare. In fact, other than Dengue and RSV, have we really every seen proof of it at all, never mind whether it is long-lasting? For example, Influenza vaccines infections do show a slight OAS effect, but vaccination still works very well.
