COVID-19 Death Rate Study 20200402

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Study on COVID-19 Annualized Death Rate

Jiang Zhou, PhD.,

Jeffrey Chow

In this study, we propose a method to calculate the annualized death rate (ADR) for COVID-19. We demonstrate that the ADR is a metric that helps us answer important questions, including what the impact of COVID-19 is on death rates for different age groups, and how many deaths will result in the United States if the herd immunity strategy is used.

According to a Business Insider article (1) dated March 2020, the COVID-19 death rates for different age groups in the United States are shown in the following table.

Age Group | COVID-19 Death Rate In First 3 Month of 2020 |

45-54 | 0.5% |

55-64 | 1.4% |

65-74 | 2.7% |

75-84 | 4.3% |

85+ | 10.4% |

These are the calculated death rates for people who had COVID-19 in the first 3 months of 2020. We develop an Annualized Death Rate (ADR) using the following approach. Suppose that we observe people who got COVID-19 for 12 months. In the first 3 months, some patients die at a certain death rate. After 3 months, some survivors continue dying at a normal death rate for 9 months. Thus at the end of 12th month, the Annualized Death Rate related to COVID-19 is calculated as the following:

COVID-19 ADR = COVID-19 death rate in the first 3 months+(100%- COVID-19 death rate in the first 3 months)*normal death rate in 9 months

In the above equation we make the following assumptions.

- After 3 months of catching COVID-19, patients either recover fully or die;
- COVID-19 survivors don’t catch the disease again in the next 9 months.

Based on the death rate in 2018 as published by CDC (2) (table below), we calculate the normal death rate in 9 months by dividing the death rate by 12 and multiplying it by 9.

Age Group | 2018 Death Rate by CDC |

45-54 | 0.4% |

55-64 | 0.9% |

65-74 | 1.8% |

75-84 | 4.4% |

85+ | 13.5% |

Taking age group 85+ as an example, the annualized death rate is calculated as the following:

COVID-19 Annualized Death Rate: 19.5% = 10.4% + (1-10.4%) * 13.5% * (9/12)

The main reason that we develop the annualized death rate related to COVID-19 is that many existing statistical data collected by governments and commercial companies are on an annual basis. By adopting ADR for COVID-19, we can compare COVID-19 death data which have only a few months of history with other data of longer history, and gain valuable insights.

Using the above approach, we calculate the COVID-19 ADR, incremental death rate related to COVID-19, and the percentage of incremental death rate related to COVID-19 for age groups older than or equal to 45.

Age Group | COVID-19 2020 First 3 Months Death Rate | COVID-19 Annualized Death Rate | 2018 Death Rate Reported by CDC | Incremental Death Rate Related to COVID-19 | % of Incremental Death Rate Related to COVID-19 |

45-54 | 0.5% | 0.8% | 0.4% | 0.4% | 100.9% |

55-64 | 1.4% | 2.1% | 0.9% | 1.2% | 131.8% |

65-74 | 2.7% | 4.0% | 1.8% | 2.2% | 124.4% |

75-84 | 4.3% | 7.4% | 4.4% | 3.1% | 69.8% |

85+ | 10.4% | 19.4% | 13.5% | 6.0% | 44.5% |

The following chart shows COVID-19 ADR versus 2018 death rate.

The chart below shows the incremental annual death rates related to COVID-19.

The above chart shows that incremental annual death rates related to COVID-19 for age groups 45-54, 55-64, 65-74, 75-84 and 85+ are 0.4%, 1.2%, 2.2%, 3.1% and 6.0%.

The following chart is the percentage of incremental annual death rate related to COVID-19, i.e., incremental annual death rate related to COVID-19 divided by normal annual death rate.

As we see, COVID-19 related annual death rates for age groups 45-54, 55-64 and 65-74 are 100.9%, 131.8% and 124.4% higher than normal death rates, respectively. The death rates related to COVID-19 for two oldest groups, i.e., 75-84 and 85+, are 69.8% and 44.5% higher than normal death rates respectively. This is not surprising as the denominators, i.e., the normal death rates for two groups, are much higher than those of other younger groups.

Some experts suggested that herd immunity (3), i.e., letting 50% to 67% of people infect with innovative conronavirus. As a result, most of them will recover and gain immunity. However, a relatively small number of deaths will happen. Using the incremental annual death rate related to COVID-19, we calculate how many deaths will happen in the United States for people equal to or older than 45 if herd immunity strategy is used.

Age Group | Incremental Death Rate Related to COVID-19 | Population in USA (Million, 2018 US Census) | Annual Incremental Death Related to Herd Immunity 50% (Million) | Annual Incremental Death Related to Herd Immunity 67% (Million) |

45-54 | 0.4% | 41.63 | 0.08 | 0.11 |

55-64 | 1.2% | 42.27 | 0.25 | 0.33 |

65-74 | 2.2% | 30.48 | 0.34 | 0.45 |

75-84 | 3.1% | 15.39 | 0.24 | 0.32 |

85+ | 6.0% | 6.55 | 0.20 | 0.26 |

Total | 1.10 | 1.47 |

The above table shows that if the herd immunity strategy is used in the United States, the incremental annual number of deaths related to COVID-19 for people equal to or older than 45 will be between 1.1 and 1.47 million.

We propose a method to calculate the annualized death rate (ADR) related to COVID-19. Based on ADR related to COVID-19 and the 2018 death rate for the population of the United States, we gain the following insights:

- Incremental annual death rates related to COVID-19 for age groups 45-54, 55-64, 65-74, 75-84 and 85+ are 0.4%, 1.2%, 2.2%, 3.1% and 6.0%, respectively.
- Percentages of incremental annual death rates related to COVID-19 for age groups 45-54, 55-64, 65-74, 75-84 and 85+ are 100.9%, 131.8%, 124.4%, 69.8% and 44.5%, respectively..
- If the herd immunity strategy is used in the United States, the incremental annual number of deaths related to COVID-19 for people equal to or older than 45 will be between 1.1 million and 1.47 million.

- https://www.businessinsider.com/coronavirus-compared-seasonal-flu-in-the-us-death-rates-2020-3
- https://www.cdc.gov/nchs/products/databriefs/db355.htm
- https://www.wildcat.arizona.edu/article/2020/03/n-herd-immunity
- https://www.worldometers.info/coronavirus/coronavirus-age-sex-demographics/