Doesn't this only apply to Dengvaxia? I can't find anything that states that Qdenga should only be used with people who've already been infected before. I also can't find anything stating there's a risk of ADE (antibody-dependent enhancement) with Qdenga as there is with Dengvaxia, which would make such a limitation necessary.
https://www.takeda.com/newsroom/newsreleases/2022/takedas-qd...
https://www.ema.europa.eu/en/medicines/human/EPAR/qdenga
https://en.wikipedia.org/wiki/Antibody-dependent_enhancement