theory
WHO pandemic bonds were "designed" to default. ("[I]nvestors holding the riskier tranche of the securities face total wipeout" in the event of a triggering outbreak of coronavirus, see link below).
The purpose was to launder money, via the WHO, to lesser developed countries where it would be funneled to hospitals and NGOs with mimimal oversight. Need to track the $$$
facts
By the way, only way to trigger a default is by "Boston-based AIR Worldwide Corp., [which] will compare the two-week average of cases with the previous two-week average to determine whether the growth rate is positive, one of the preconditions for the payout."
Sauce: https://www.bloomberg.com/news/articles/2020-03-18/pandemic-bond-payouts-likely-to-be-held-up-by-fine-print