Overview: 1) Immunological studies; 2) Antibody studies; 3) PCR studies; 4) Modelling studies; 5) Other studies; 6) Age of death; 7) Hospitalization rate; 8) Nursing homes; 9) Overall mortality; 10) Development of the pandemic. IFR: Infection fatality rate (population-adjusted).
1) Immunological studies
Immunological research indicates that serological antibody studies, which measure antibodies in the blood (IgG and IgM) and typically found population-based IFR values between 0.1% and 0.5% (see below), may detect only about 20% of infections, as most people neutralize the coronavirus with their mucosal (IgA) or cellular (T cells) immune system while developing only mild symptoms or no symptoms. This means IFR values may drop by a factor of five to values at or below 0.1%.
|Switzerland||May 23||IgA||5||Report / Study|
|China||June 16||IgG||6||Report / Study¹|
1) Only 16% of likely infected HCW had IgG; 2) 81% of unexposed individuals had cross-reactive T-cells; 3) Less than 20% of symptomatic individuals had IgG antibodies; 4) 60% cross-reactive IgG in children.
2) Antibody seroprevalence studies
Population-based antibody seroprevalence studies.
|Austria||June 25||Ischgl hotspot||<0.26||Report|
|Global||June 8||23 studies
Below 70 years
|Germany||May 4||Heinsberg hotspot||<0.36²||Study|
|Iran||May 1||Guilan province||<0.12||Study|
|USA||April 30||Santa Clara County||0.17||Study|
|Denmark||April 28||Blood donors (<70y)||0.08||Study|
|USA||April 24||Miami-Dade County||<0.18||Report|
|USA||April 21||Los Angeles County||<0.20||Study|
1) Median value; 2) The adjusted IFR is 0.27% (page 9). Note: Some of these studies are preprints.
3) Controlled PCR studies
Controlled PCR studies in population subgroups.
|Germany||July 25||Meat factory||1766||0.00||Study|
|France||May 21||Health workers||28050||0.05||Study|
|USA||May 10||MLB employees||5603||0.00||Report|
|France||May 10||Aircraft carrier||1046||0.00||Report|
|USA||May 10||Aircraft carrier||1156||0.09||Report|
|USA||May 1||Tennessee prison||1349||0.00||Report|
|Italy||April 28||Health workers||26657||0.30¹||Study|
|USA||April 17||Boston homeless||146||0.00||Report|
|USA||April 17||Boston blood donors||200||0.00||Report|
|USA||April 13||NYC pregnant women||215||0.00||Study|
|Ship||March 17||Diamond Princess||700||0.13²||Study|
1) See table below; 2) Age-adjusted IFR based on US population.
4) Epidemiological models
Covid-19 IFR based on epidemiological models or predictions. These values are often somewhat higher than the actual values based on serological antibody studies (see above). In May 2020, the US CDC published a best estimate IFR of 0.26% (based on 35% asymptomatic cases).
|USA||May 20||CDC estimate||0.26¹||Study|
New York City
|China||March 30||Mainland China||0.66||Study|
|China||March 13||Wuhan city||0.12||Study|
|China||March 9||Mainland China||0.50||Study|
1) 0.4% symptomatic CFR and 35% asymptomatic cases; 2) Based on 29% prevalence and 50,000 deaths; 3) The IFR is 0.50 excluding nursing homes.
5) Additional antibody and PCR studies
These studies determine the prevalence of recent or current Covid-19 infections in a population or region. In most cases, they find that Covid-19 is much more widespread than previously assumed, with most people showing no or only mild symptoms.
Immunological research (see above) indicates that antibdody prevalence values may have to be multiplied by an additional factor of up to five to get the actual coronavirus prevalence values, because many mild cases neutralize the virus with their mucosal immune system.
|Germany||June 30||Blood donors||1.3%||Study|
|Czech Rep.||May 15||South Bohemia||5%||10x||Report|
|Global||May 5||< 65 years old||Study|
|Japan||May 5||Kobe City||2.7%||396x||Study|
|USA||May 2||New York State
New York City
|Spain||May 2||Health workers||11.2%||Study|
|Netherlands||April 29||Blood donors||2.7%||Study|
|France||April 23||Northern France||3%||Study|
|USA||April 19||Chelsea MA||32%||16x||Report|
|Iceland||April 14||Iceland (PCR)||0.8%||Study|
6) Median age of Covid-19 deaths per country
Half of all deaths were below, half were above the median age.
7) Hospitalization rate
Initial estimates based on Chinese data assumed a very high 20% hospitalization rate, which led to the strategy of ‘flattening the curve’ to avoid overburdening hospitals. However, population-based antibody studies (see above) have since shown that actual hospitalization rates are close to 1%, which is within the range of hospitalization rates for influenza (1 to 2%).
The US CDC found that Covid-19 hospitalization rates for people aged 65 and over are “within ranges of influenza hospitalization rates”, with rates slightly higher for people aged 18 to 64 and “much lower” (compared to influenza) for people under 18.
8) Percentage of Covid-19 deaths in care homes
In many countries, deaths in care homes account for 30 to 60% of all additional deaths. In Canada and some US states, care homes account for up to 80% of all “Covid19-related” deaths. In Sweden, deaths in nursing homes plus nursing apartments account for 75% of all deaths.
Source: Mortality associated with COVID-19 outbreaks in care homes (LTC Covid, May 21, 2020)
Source: The Covid-19 Nursing Home Crisis by The Numbers (Freopp, June 19, 2020)
9) Overall mortality
In countries like the US, the UK, and also Sweden (without a lockdown), overall mortality since the beginning of the year is in the range of a strong influenza season; in countries like Germany, Austria and Switzerland, overall mortality is in the range of a mild influenza season.
A comparison between the number of coronavirus deaths predicted by the influential model of Imperial College London (no measures or moderate measures) and the actual number of deaths in Sweden shows that the model strongly overestimated the impact of the epidemic:
10) Development of the pandemic
Even in countries without a lockdown, the epidemic reached its peak within a few weeks of the outbreak. However, many media showed cumulative deaths per day of report (left) instead of daily deaths per day of death (right), falsely implying an ever escalating situation.
- Additional Covid-19 Antibody Serological Studies (Dr. Henrik Jarlov)
- Global Covid-19 Case Fatality Rates (Oxford Center for Evidence-Based Medicine)
- Rate of positive Covid-19 tests per country over time (SPR)