Studies on Covid-19 Lethality

Updated: April 2021
Published: May 2020
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Overview

1) Antibody studies 2) Immunology 3) Median age of death 4) Hospitalizations 5) Nursing homes 6) Overall mortality 7) Influenza comparison 8) Seroprevalence per country

1) Antibody studies

The covid infection fatality rate (IFR) depends on demographics (age and risk structure), public policies (e.g. protection of care homes), and medical treatment quality. In most Western countries, the median age of covid deaths is 80+ years and about 50% of deaths occurred in care homes (s.b.)

For comparison, the IFR of seasonal influenza, against which prior immunity and vaccines exist, is about 0.05% to 0.1%; the IFR of epidemic and medium pandemic influenza, such as in 1936, 1951, 1957 and 1968, is about 0.3%; the IFR of the 1918 pandemic influenza was about 2%. (Source)

In terms of covid-19 IFRs, an important difference exists between places with and without a partial or total collapse of local health and elderly care, and between the early and late pandemic phase. In the following table, NNH refers to the non-nursing home population (see section 5).

Country Published Population IFR (%) Source
Global
Global Oct. 2020 51 locations
Below 70 years
0.20¹
0.04¹
Ioannidis
Africa
Kenya July 2020 National <0.1 Uyoga
Malawi Aug. 2020 National <0.1 Grace
Asia
India July 2020 Delhi
Mumbai
0.14
0.23
India
Iran May 2020 Guilan province 0.12 Shakiba
Europe
Austria June 2020 Ischgl (NNH) 0.26 von Laer
Belgium Dec. 2020 General population
Incl. care homes
40 to 49 years
0.58
1.47
0.05
Hens
Denmark April 2020 Blood donors (<70y) 0.08 Erikstrup
England Aug. 2020 General (MCT)
General (ONS)
0.30
0.49
CEBM
Aug. 2020 General population
Incl. care homes
45 to 64 years
Below 44 years
0.90
1.43
0.50
0.03
Ward
Germany May 2020
Nov. 2020
Heinsberg (NNH)
Munich (NNH)
0.36
0.48²
Streeck
LMU
Iceland Sept. 2020 General population
Below 70 years
0.30
0.10
NEJM
Italy
(Lombardy)
Aug. 2020 Below 70 years
Below 50 years
80+, first phase
80+, second ph.
0.43
<0.01
30.40
8.10
Poletti
Spain
(early phase)
Aug. 2020 Confirmed covid
Excess deaths
Below 50 years
Below 40 years
0.82
1.07
<0.10
<0.03
Pollan
Sweden June 2020 Stockholm (NNH)
Stockholm <70y
0.35³
0.09
FOHM
Switzerland July 2020
Aug. 2020
Geneva (NNH)
Zurich (NNH)
0.324
0.304
Perez
Aguzzi
Latin America
Brazil Sept. 2020
Sept. 2020
Maranhao
Manaus
0.17
0.28
da Silva
Buss
United States
Indiana Sept. 2020 General population 0.26 AIM
Santa Clara April 2020 General population 0.175 Bendavid
Miami-Dade April 2020 General population 0.185 Miami
Los Angeles April 2020 General population 0.205 Sood
New York City
(early phase)
June 2020 Overall 0.70 Stadlbauer
June 2020 Confirmed
Probable
25 to 44 y.
<25 years
1.10
1.45
0.12
0.01
Yang

1) Median values; 2) 0.76% including nursing homes (36% of deaths); 3) 0.58% including Stockholm nursing homes (about 40% of deaths, see page 23); 4) 0.64% and 0.60% including nursing homes;  5) These US studies may underestimate the true IFR, as they were done early during an accelerating pandemic.

Belgium: IFRs for entire population vs. non-nursing home population (Molenberghs)

The above chart shows the very significant difference between IFRs in the entire population (including nursing homes, left) and in the non-nursing home population (right) at the example of Belgium. The IFR in 85-year-old nursing home patients (about 20%) is almost 20 times higher than the IFR in people of the same age outside of nursing homes (about 1%).

2) Immunological aspects

Immunological research indicates that serological antibody studies, which measure antibodies in the blood (mostly IgG), may detect only about 50% to 80% of all coronavirus infections, depending on the sensitivity of the assay, the timing of the test, and the population tested.

This is because some people neutralize the coronavirus primarily with their mucosal (IgA) or cellular (T-cells) immune system and develop only mild symptoms or no symptoms. These people may develop no measurable IgG antibodies or may show them only for a certain time.

The following chart shows that six months after an infection, the sensitivity of antibody assays in non-hospitalized patients ranged from 98% (e.g. Roche) to just 30% (e.g. the widely used Abbott assay). Thus, some antibody studies may underestimate infections and overestimate IFRs.

Sensitivity of various coronavirus antibody assays (Peluso et al)

3) Median age of Covid-19 deaths per country

Half of all deaths were below, half were above the median age.

Country Median age
Source
Australia 82 years DOH
Austria 82 years EMS
Belgium 86 years IBS
Brazil 70 years MDX
Canada 86 years HCSC
England 82 years NHS
France 84 years SPF
Germany 83 years RKI
Italy 82 years ISS
South Africa 62 years SAC
Spain 82 years MDS
Sweden 84 years FOHM
Switzerland 86 years BAG
USA 78 years CDC

 

The following chart shows the percentage of covid deaths per age group in various countries. While in many European countries, up to 90% of deaths affect people older than 70 years of age, in many Latin American countries, up to a third of deaths affect people younger than 60 years of age.

Percentage of covid deaths per age group, per country, by February 2021 (Sinichol)

4) 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 closer to 2%, which is comparable to 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 somewhat higher for people aged 18 to 64, but “much lower” (compared to influenza) for people under 18.

In hotspots like New York City, the hospitalization rate based on antibody studies was about 2.5% (20% or 1.7 million people with antibodies and 43,000 hospitalizations by early May 2020). The lower-than-expected hospitalization rate may explain why many covid-19 ‘field hospitals’, e.g. in the US and the UK, remained largely unused.

5) Percentage of Covid-19 deaths in care homes

In most Western countries, deaths in care homes account for 30% to 60% of all covid deaths. In Canada and some US states, care homes account for up to 80% of all covid-related deaths. In Sweden, deaths in nursing homes and nursing apartments account for 70% of all deaths.

Percentage of covid deaths in care homes (Source: LTC Covid, February 2021)

6) Overall mortality

By the end of March 2021, there were close to 3 million covid deaths in close to 8 billion people. At a global infection attack rate of 10% to 30%, this results in an average global covid lethality (IFR) of 0.1% to 0.35% and a global covid mortality of about 0.035%. By comparison, the 1918 flu pandemic had a global mortality of about 2.3% (40 million deaths in 1.8 billion people).

See also: Covid-19 Mortality: An Overview (March 2021)

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 indicates that the model significantly overestimated the impact of the epidemic:

Sweden: ICL model predictions versus actual Covid-19 deaths (HTY/FOHM)

7) Coronavirus vs. influenza pandemics

The following chart shows US mortality by age in previous pandemic years compared to 2020 US excess mortality, which consisted primarily (>75%) of confirmed and suspected covid-19 deaths, according to the CDC. To learn more about this comparison, please read this article.

Pneumonia and influenza mortality by age in previous pandemic years (Glezen, 1996) vs. 2020 excess mortality by age, primarily driven by covid-19, overall and excluding nursing homes (SPR based on CDC data)

8) Antibody seroprevalence per country

Percentage of people with measurable antibodies to the new coronavirus.

Country Date Region Antibodies Source
Europe
Belgium June 2020 National
Brussels
7%
12%
Herzog
Denmark Nov. 2020
Aug. 2020
National
Copenhagen
3.9%
3.2%
SSI
SSI
England July 2020 National
North West
London
6%
12%
17%
PHE
France Mar. 2021 National
Paris region
21%
37%
PFR
Germany Mar. 2021
June 2020
April 2020
National
National
Gangelt
15%
<2%
15%
RKI
Hungary June 2020 National
Budapest
0.7%
0.8%
Merkely
Iceland July 2020 National 0.9% NEJM
Ireland Aug. 2020 National
Dublin
1.7%
3.1%
HSPC
Italy July 2020 National
Bergamo
Lombardy
Sicily
2.5%
38%
7.5%
0.3%
ISTAT
Netherlands July 2020 National
South
4%
16%
RIVM
Russia June 2020 National
Moscow
Petersburg
14%
20%
5.7%
TMT
TMT
EUSP
Spain Dec. 2020
Dec. 2020
National
Madrid
10%
19%
Franco
Sweden May 2020
Nov. 2020
National
Stockholm
5%
31%
FOHM
DNSE
Switzerland Jan. 2021
Nov. 2020
Jan. 2021
Zurich
Ticino
Geneva
11%
16%
21%
BAG
Ukraine Jan. 2021 National 43% LNMU
Americas
Brazil Aug. 2020
Feb. 2021
Maranhao
Sao Paulo
40%
25%
Silva
SPS
Canada June 2020 National
Quebec
Ottawa
Vancouver
0.7%
2.2%
1.3%
0.6%
BCA
USA Mar. 2021 National
New York
Oregon
S. Dakota
30%
35%
11%
48%
C19P
Asia
China Apr. 2020


May 2020
Wuhan
Hubei
Rest
Wuhan
4.5%
0.5%
<0.1%
2.4%
Lancet


CMI
India Jan. 2021 Delhi
National 1
56%
22%
NCDC
Japan July 2020 Tokyo 1.2% Nawa
Iran July 2020 National
Qom
Rasht
17.1%
58.5%
72.6%
Lancet
South Korea Oct. 2020 National 0.6% Lee
Africa
Congo July 2020 Brazzaville 20% IJID
Kenya June 2020 National
Nairobi
5.2%
8.3%
Uyoga
Nigeria Oct. 2020 Lagos 23% NCDC
South Africa Jan. 2021 National 50% MDX

 

Estimated national immunity levels per country by December 2020 (Source: Bloomberg)

See also


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