Pre-vaccine fatality rates lower than previously thought
Lower than previously thought
Impact of non-pharmaceutical interventions (NPIs) to reduce COVID-19 mortality and healthcare demand (16th March 2020)
Imperial College COVID-19 Response Team
https://www.imperial.ac.uk/media/imperial-college/medicine/sph/ide/gida-fellowships/Imperial-College-COVID19-NPI-modelling-16-03-2020.pdf
We assumed
Incubation period of 5.1 days
Infectious 12 hours before to 4.6 days after
R0=2.4
Non-uniform attack, applied to the GB population
Result in an IFR of 0.9%
with 4.4% of infections hospitalised
10.4 day stay
30% of hospitalised, ICU (50% death rate)
(not accounting for the potential negative effects of health systems being overwhelmed on mortality)
Age-stratified infection fatality rate of COVID-19 in the non-elderly informed from pre-vaccination national seroprevalence studies
Stanford California, Rome, Montreal
https://www.medrxiv.org/content/10.1101/2022.10.11.22280963v1
40 eligible national seroprevalence studies,
covering 38 countries with pre-vaccination seroprevalence data.
For 29 countries publicly available age-stratified COVID-19 death data,
and age-stratified seroprevalence information were available,
and were included in the primary analysis.
IFRs for 0 to 59 years
median IFR = 0.035%
(IQR, 0.013 – 0.056%)
Without accounting for seroreversion
(average time from seroconversion to seroreversion at 3-4 months)
IFRs for 0 to 69 years
IFR = 0.095%
0 to 19 years
IFR = 0.0003%
20 to 29 years
IFR = 0.003%
30 to 39 years
IFR = 0.011%
40-49 years
IFR = 0.035%
50-59 years
IFR = 0.129%
60-69 years
IFR = 0.501%
At a global level
Pre-vaccination IFR,
may have been as low as,
0 to 59 years = 0.03%
0 to 69 years = 0.07%
Global population
94% younger than 70 years
91% younger than 65 years
86% younger than 60 years
The current analysis suggests a much lower pre-vaccination IFR in non-elderly populations than previously suggested.
Large differences did exist between countries and may reflect differences in comorbidities and other factors.
These estimates provide a baseline from which to fathom further IFR declines with the widespread use of,
Vaccination
Prior infections
Evolution of new variants.
Unmitigated epidemic
(March 2020)
UK deaths = 510,000 (168,913)US deaths = 2.2 million (1,065,152)
During 2021 and 2022
Vaccination, new variants, prior infections,
resulted in a marked decline in the IFR