In insurance, there is a concept of Incurred claims But Not Reported (IBNR). These are claims for services that have been performed by a clinician but the bills have not hit the insurer’s claims system. IBNR is often predictable and can be used to inform reasonable guesses about what is still out there but not yet reported.
I think IBNR can be an analogue for COVID-19 as COVID-19 has predictable progressions. COVID-19 has Infected But Not Resolved (IBNR) cases.
A person infected today is highly unlikely to show up in today’s testing. Most likely they will show up in testing early next week.##
A person tested next week and found to be positive is unlikely to be admitted to a hospital on the day of the positive test. Instead, if they are ever in a hospital, they are likely to be in a hospital two weeks from today.
A person admitted to the hospital two weeks from today is likely to be discharged in late May or early June. However if they are to die, they are unlikely to die on the day of admission. Instead, they are likely to survive for several days before dying. **
A person infected today is unlikely to show up as a death until Memorial Day.
If we can safely add up median time from infection to symptoms and then symptoms to hospitalization, that sums to a back of the envelope span of 12 to 13 days.
We’ll have to add time from hospitalization to death. But this morbid math has a point. The next 7 to 10 days of deaths have almost entirely been baked into the cake as these are individuals who were infected before states started trying to open up again. We’re not going to get a reliable signal on mortality due to policy changes for at least another two weeks in the states that have been early and aggressive in re-opening. Right now, there are Infections incurred But Not Resolved that are working their way through the system and most of this IBNR is from the physical distancing policy and behavioral regime.
## DOI: 10.7326/M20-0504
** Lancet Infect Dis 2020 Published Online
March 12, 2020 https://doi.org/10.1016/S1473-3099(20)30195-X