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Effects of SARS-CoV-2 on Human Populations

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(Last updated: Apr 24th 2021)

A scenario describing the effects to a human district of 10,000 non-vaccinated inhabitants if a sars-cov-2 virus variant entered the community. Research papers used are predominantly from countries in the U.S. and Europe and many involve randomized population samples and official world-wide data.  Note that these are approximations, every city will have variant results depending on the population’s age distribution, health and many other factors. These projections are expected to further narrow down and become more precise with future research. The most difficult part to estimate seems to be the percentage of population that would fend off the virus through their innate and previously built adaptive immunity, and test negative.

  • ~10,000 people = 100% = 1 City District

Innate (T-cell) & Adaptive Immunity
– Projected Test negativity rate
 (in 10,000 people)

  • 2,000-6,000 individuals (20%-60%) would test negative and beat the virus naturally (projected)

Resources:

  • “Such T-cell response was not specific to recovered patients only but was also present in 40–60% of the individuals who were not exposed to SARS-CoV-2. Further analysis showed that they had pre-existing cross-reactive CD4+ T cells, which might have been generated in response to some previous coronavirus infection.”
    “The novel coronavirus, SARS-CoV-2 falls under the genus β-CoV, as it shares 88% sequence identity with SARS-CoV-like coronaviruses (derived from bat) but is only 79% identical to SARS-CoV and 50% identical to MERS-CoV”
    Overview of Immune Response During SARS-CoV-2 Infection: Lessons From the Past – link
  • “At least six studies have reported T cell reactivity against SARS-CoV-2 in 20% to 50% of people with no known exposure to the virus.”
    “In Germany reactive T cells were detected in a third of SARS-CoV-2 seronegative healthy donors (23 of 68).”
    “Serological surveys since the peak indicate that at most only around a fifth of people have antibodies to SARS-CoV-2: 23% in New York, 18% in London, 11% in Madrid.”
    Covid-19: Do many people have pre-existing immunity? – link
  • “We showed that patients (n = 23) who recovered from SARS (the disease associated with SARS-CoV infection) possess long-lasting memory T cells that are reactive to the N protein of SARS-CoV 17 years after the outbreak of SARS in 2003; these T cells displayed robust cross-reactivity to the N protein of SARS-CoV-2. We also detected SARS-CoV-2-specific T cells in individuals with no history of SARS, COVID-19 or contact with individuals who had SARS and/or COVID-19 (n = 37). SARS-CoV-2-specific T cells in uninfected donors exhibited a different pattern of immunodominance, and frequently targeted NSP7 and NSP13 as well as the N protein.”
    SARS-CoV-2-specific T cell immunity in cases of COVID-19 and SARS, and uninfected controls – link
  • “We demonstrate the presence of pre-existing humoral immunity in uninfected and unexposed humans to the new coronavirus. SARS-CoV-2 S-reactive antibodies were readily detectable by a sensitive flow cytometry-based method in SARS-CoV-2-uninfected individuals and were particularly prevalent in children and adolescents. “
    Pre-existing and de novo humoral immunity to SARS-CoV-2 in humans – link
  • “Importantly, we detected SARS-CoV-2-reactive CD4+ T cells in ∼40%-60% of unexposed individuals, suggesting cross-reactive T cell recognition between circulating “common cold” coronaviruses and SARS-CoV-2. “
    Targets of T Cell Responses to SARS-CoV-2 Coronavirus in Humans with COVID-19 Disease and Unexposed Individuals  – link
  • “The company’s trials found some people who had coronavirus but tested negative for antibodies went on to test positive for T cells – meaning more people may have some immunity than previously thought – and for longer.:
    Coronavirus: Test for Covid-19 T cells immunity developed – link

Test positivity rate (in 10,000 people)

  • U.S.  ~174-930 will Test Positive (1.74%-9.3%)

  • Italy ~260-900 will Test Positive (2.6%-9%)

  • Canada ~200 will Test Positive (2%)

  • Diamond Princess ~1,790 Tested Positive (17.9%)

Resources:

  • U.S. Indiana (PCR) – 1.74% (2.3%-8.3%)
    “Statewide, 1.74% of persons (unweighted n = 47) had a positive RT-PCR test result (95% CI = 1.10%–2.54%), and 1.01% (95% CI = 0.76%–1.45%) (unweighted n = 38) had samples that were seropositive, resulting in an estimated overall population SARS-CoV-2 prevalence of active or current infection in Indiana of 2.79% (95% CI = 2.02%–3.70%). The overall prevalence was significantly higher among Hispanics (8.3%) than among non-Hispanics (2.3%) (p = 0.03).” – link
  • U.S. (antibodies)  – 9.2% (8.7%–9.8%)
    “Seroprevalence of SARS-CoV-2 was 8·0% (95% CI 7·7–8·4) in the sample, 8·3% (8·0–8·6) when standardised to the US dialysis population, and 9·3% (8·8–9·9) when standardised to the US adult population. When standardised to the US dialysis population, seroprevalence ranged from 3·5% (3·1–3·9) in the west to 27·2% (25·9–28·5) in the northeast. Comparing seroprevalent and case counts per 100 000 population, we found that 9·2% (8·7–9·8) of seropositive patients were diagnosed. ” – link
  • U.S. (Vit-D) – 9.3% (5.9%-8.1%-12.5%)
    “The SARS-CoV-2 positivity rate was 9.3% (95% C.I. 9.2–9.5%). The SARS-CoV-2 positivity rate was higher in the 39,190 patients with “deficient” 25(OH)D values (<20 ng/mL) (12.5%, 95% C.I. 12.2–12.8%) than in the 27,870 patients with “adequate” values (30–34 ng/mL) (8.1%, 95% C.I. 7.8–8.4%) and the 12,321 patients with values ≥55 ng/mL (5.9%, 95% C.I. 5.5–6.4%).” – link
  • Canada ~2%, U.S. ~8%
    “In Canada, the current test positivity rate for the entire country is around 2%. In the U.S., the overall test positivity rate is 8%, according to the CDC.”     – NOTE: “If you had one per cent of the people testing positive of every person tested, if more people are getting tested, it would still be one per cent of all people that should be positive, just as a bigger number,” – link
  • U.S.  ~3.7% – 5.6%.  link
  • U.K. – 0.06%-0.40% (April 26 – June 28, 2020) – above 1% (end of October, 2020)
    Community prevalence of SARS-CoV-2 in England from April to November, 2020: results from the ONS Coronavirus Infection Survey    – link
  • Italy – 9% – link
  • Italy – The testing revealed that at the start of the lockdown, 2.6 percent of the population (73 people) were positive for SARS-CoV-2, while after a couple of weeks only 1.2 percent (29 people) were positive. At both times, around 40 percent of the positive cases showed no symptoms (asymptomatic). The results also show it took on average 9.3 days (range of 8-14 days) for the virus to be cleared from someone’s body. – link
  • Diamond Princess –17.9%
    “The estimated asymptomatic proportion was 17.9% (95% credible interval (CrI): 15.5–20.2%). Most infections occurred before the quarantine start.”
    Estimating the asymptomatic proportion of coronavirus disease 2019 (COVID-19) cases on board the Diamond Princess cruise ship, Yokohama, Japan, 2020 –  link

Symptoms (in 10,000 people)

  • U.S. ~122-651 will have symptoms (70% of (1.74%-9.3% positive))=1.22%-6.51%)

  • Italy ~156-540 will have symptoms – hospitalization  (60% of (2.6%-9% positive))= 1.56%-5.4%)

  • Canada ~130 will have symptoms (65% of 2% positive)=1.3%)

Resources:

  • Italy – Around 40 percent of the positive cases showed no symptoms (asymptomatic). The results also show it took on average 9.3 days (range of 8-14 days) for the virus to be cleared from someone’s body. – link
  • Canada – Of children with a positive test result for SARS-CoV-2, 714 (35.9%) reported being asymptomatic. – link
  • Canada – At least 1 in 3 COVID-19 infections are asymptomatic, study suggests – link
  • U.S. – 30 Percent of People With COVID-19 Show No Symptoms – link

Hospitalization/ICU (in 10,000 people)

(Percentages applied to symptomatic individuals)

  • U.S. ~100 people will need hospitalization
    (21%-31% of     1.22%-6.51% symptomatic ≈ 26% of 3.87% ≈ ~1%)

  • U.S. ~30 people will need ICU 
    (5%-11% of     1.22%-6.51% symptomatic ≈ 8% of 3.87% ≈ ~0.3%)

  • Italy ~ people will need ICU 
    (16% of     1.56%-5.4% symptomatic ≈ 16% of 4.26% ≈ ~0.68%)

  • Canada ~20 people will have severe disease & need hospitalization (15% of 1.3% symptomatic = 0.195%)*

  • Canada ~6 people will need ICU 
    (5% of     1.3% symptomatic = 0.065%)

Resources:

  • * Note – A “patient” is defined as a person that “has symptoms compatible with COVID-19″ – link
  • Canada – “While most people that develop COVID-19 present with mild or uncomplicated illness, up to 15% of patients may develop severe disease requiring hospitalization and oxygen support and up to 5% may require admission to an intensive care unit (ICU)” – Clinical management of patients with COVID-19: Second interim guidance – link
  • Italy – “Publicly available data indicate that ICU admissions (n = 556) represented 16% of all patients (n = 3420) who tested positive* for COVID-19. As of March 7, the current total number of patients with COVID-19 occupying an ICU bed (n = 359) represents 16% of currently hospitalized patients with COVID-19 (n = 2217)”. – link
  • U.S. Hospitalizations/Ventilators
    “Between 21% and 31% of Covid-19 patients in the U.S. have required hospitalization, and 5% to 11% have required intensive care. 3.5% of them needed ventilators, that would be 0.245%” – link

Adverse Effects (in 10,000 people)
(Long-term symptoms  – concentration, memory issues, etc.)

  • “UK based COVID Symptom Study that analyzes data from 4.3 million participants, suggests most people recover from COVID-19 within two weeks, but 10 per cent may still have symptoms after three weeks and some may suffer for months.” link
  • “Percent of hospitalized that have memory loss 34%. 27% concentration months later, ~50% (France)” – link
  • ” In the six months after diagnosis, 33.6% of patients with COVID-19 had a subsequent diagnosis of any neurologic or psychiatric illness. These were more frequent among those hospitalized (38.7%), who were in ICUs (46.4%), and those with encephalopathy (62.3%).” – link

Mortality Rates (Case Fatality Rates – CFR) (in 10,000 people)

(Percentages applied to positive-test-case numbers)
Note: Infection fatality rate (not used here) definition is “proportion of deaths among all infected individuals, including all asymptomatic and undiagnosed subjects” – link

  • U.S. ~19 people will die (~18 will be over age 70 (95%))
    (3.4% of     1.74%-9.3% positive tests ≈     3.4% of 5.52% ≈  0.19%) – (0.1805% Age 70+, 0.0095% Age 70-)

  • Italy ~20 people will die (~19 will be over age 70 (95%))
    (3.4% of     2.6%-9% positive tests ≈     3.4% of 5.8% ≈  0.20%) – (0.19% Age 70+, 0.01% Age 70-)

  • Canada ~6 people will die (~6 will be over age 70 (95%))
    (3.4% of     2% ≈  0.06%) – (0.057% Age 70+, 0.003% Age 70-)

Resources:

  • Global – “CFR decreased to between 4.3% and 11.0%, and later to 3.4%. The rate reported outside China in February was even lower 0.4%” – link
  • Global – “Globally, about 3.4% of reported COVID-19 cases have died. By comparison, seasonal flu generally kills far fewer than 1% of those infected. “ – link
  • John Ioannidis (WHO) data – “0.09% in locations with COVID-19 population mortality rates less than the global average (< 118 deaths/million), 0.20% in locations with 118–500 COVID-19 deaths/million people and 0.57% in locations with > 500 COVID-19 deaths/million people. In people < 70 years, infection fatality rates ranged from 0.00% to 0.31% with crude and corrected medians of 0.05%.” Referenced paper (W.H.O.)
  • Canada – “The adjusted CFR in Canada was estimated to be 3.36% nationwide. At the provincial level, the adjusted CFR was the highest in Quebec (5.13%)—where the proportion of deaths among older individuals was also the highest among the four provinces—followed by Ontario (3.17%), British Columbia (1.97%), and Alberta (1.13%).” – Regional Variability in COVID-19 Case Fatality Rate in Canada, February–Feb 2021 – link
  • U.S. – Infection-fatality ratio = 0.58% – Indiana – link
  • Diamond Princess – “fatality ratios (CFR, IFR)  2.6% (95% (CI): 0.89-6.7) and 1.3% (95% CI: 0.38-3.6), respectively. CFR and IFR in China to be 1.2% (95% CI: 0.3-2.7) and 0.6% (95% CI: 0.2-1.3), respectively.” – link
  • Italy “The overall case-fatality rate in Italy (7.2%) is substantially higher than in China (2.3%).” – link
  • Mortality rates by age: 0.95% above age 70 Canadian Data , U.S. Data

Hypothetical Worst-Case Scenario – Global Projection (100% Exposure in 10,000 people)

  • if 100% of people get exposed,
    ~9,720-9,860     people will Live (~97.2%-98.6%)
    (~9,930-9,986 Age below 70 (~99.3-99.86%) will live)

  • ~4,000-8,000 will Test Positive – Test positivity rate – 40%-80%

  • ~2,600-5,000 will have Symptoms  (~65% of T.P.R.) ~26%-52%

  • ~340-680 people will need Hospitalization/ICU (~13% of Symptomatic) ~3.4%-6.8%

  • 140-280 people will die (~3.4% of T.P.R.) ~ 1.4%-2.8%

  • 7-14 people below age 70 will die (~5% of Total Fatality) ~0.7%-0.14%

Resources

  • Canada – Most people with COVID-19 have uncomplicated or mild illness (approximately 80%). Clinical management of patients with COVID-19: Second interim guidance – link
  • Global – Mortality rates by age: 0.95% above age 70 Canadian Data , U.S. Data

Real World Examples of high-spreading events

  • An Outbreak of Covid-19 on an Aircraft Carrier – link
    26% Tested Positive,
    14.3% (76.9 of T.P.R.) had symptoms,
    0.44% (1.7% of T.P.R.)  hospitalized,
    0.08 (0.3% of T.P.R.) ICU,
    0.02% died.


EXTRA INTERESTING INFORMATION

 

Virus and Social Distancing Simulation/Modelling
(What happens if lock-down is not 100%)
Simulating an Epidemic (YT)

Stay-at-home policy – “exception fallacy”
Scientific Reports

Countries Lock-down Comparison Charts
https://ig.ft.com/coronavirus-lockdowns/

Cancer Mortality Rate
83,400 people are estimated to die in Canada, in 2020. With a population size of 37.59 Million, this accounts for 0.2% cancer mortality rate. COVID-19 mortality rate in Canada is 0.09%.
https://www.cancer.ca/en/cancer-information/cancer-101/cancer-statistics-at-a-glance/?region=on

EuroMomo Data on Excess Deaths in Europe per Country since 2016 https://www.euromomo.eu/graphs-and-maps#z-scores-by-country

Excess Mortality across Countries in 2020
cebm.net

Nature Magazine – Stay-at-home policy article
https://www.nature.com/articles/s41598-021-84092-1

Spain Sewage – March 2019
https://globalnews.ca/news/7119856/coronavirus-sewage-barcelona-march-2019/

Wall street Journal – Extreme Poverty Graph
https://www.wsj.com/articles/coronavirus-has-thrown-around-100-million-people-into-extreme-poverty-world-bank-estimates-11602086400?reflink=share_mobilewebshare

A simplicized formula for average covid deaths:
0.5% (av. pos. test. rate) * 0.2% (av. death rate) = 0.1% deaths
Out of that, 95% will die above 70 years of age.
So chance of someone below age of 70 dying is 0.1% * 0.05% = 0.005% (and 0.095% vice versa)

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