30 December 2021 Blog Post: Decoupling of Cases and Bad Outcomes in COVID-19
A big promise of widespread vaccination and, now, booster shots is their potential to “decouple” SARS-CoV-2 infection from significant morbidity (illness, hospitalization, mechanical ventilation, ICU admission). But is this something we are seeing in reality? Well, yes it is.
Given that those who are vaccinated may still become infected (but have mild disease) combined with the fact that the Omicron variant intrinsically seems to be associated with more mild illness, hospitalization has been forwarded as a more reliable indicator if COVID-19’s impact on the public’s health. However, hospitalization may be blurred as some patients may be admitted for other diagnoses and coincidentally test positive for SARS-CoV-2.
Mortality is, obviously, the outcome we most want to avoid while acknowledging that infection itself can lead to lifelong consequences such as long-COVID syndrome.
The graph below compares incident (new) cases aggregated by week with 2020 numbers in Blue and 2021 numbers in Red. We currently remain below our 2020 case numbers but cases are rising fast and I have every expectation that we will meet or exceed last year’s case rates in the coming days to weeks.
But look below at the second figure which plots mortality rates.
Mortality rates in 2021 are simply not budging off their baseline rate of 0.1 daily deaths per 100,000 population (1 in a million, literally). Of course, mortality is a lagging indicator and the time delay between case identification and death combined with LA County’s slow reporting may obscure this relationship. Nevertheless, there seems to be good evidence of “decoupling” mortality from SARS-CoV-2 infection – a conjoint function of Omicron’s intrinsic infectiousness but attenuated lethality, vaccination, booster shots, not yet overloaded hospitals, and early treatment.
𝗦𝗶𝗴𝗻 𝗨𝗽 𝗳𝗼𝗿 𝗢𝘂𝗿 𝗡𝗲𝘄𝘀𝗹𝗲𝘁𝘁𝗲𝗿