Nivel primary care database

Nivel Primary Care Database (Nivel Zorgregistraties Eerste Lijn) registers and analyzes the records of hundreds of GP practices across the country. In addition, Nivel works together with some 40 Measurement Stations: GP practices that make their data available every week. The data below can be considered accurate and representative for the entire Dutch population. I received this data as part of my research into Humidity and SARS-CoV-2.

Influenza Cases – March through October

2015 – 208,935 – 1.24% of the population
2016 – 166,812 – 0.98% of the population
2017 – 157,905 – 0.92% of the population
2018 – 226,140 – 1.32% of the population
2019 – 144,737 – 0.84% of the population

COVID-19 Cases – March through October

2020 – 339,030 – 1.94% of the population.
It should be noted however that the test volume for COVID-19 has been increased enormously. From 17,080 per week in March to 197,534 per week in November.

Case Fatality Rates Explained

The Case Fatality Rate (CFR) is a way of measuring the mortality rate of viruses. It’s the amount of deaths divided by the amount of registered cases, expressed as a percentage.

Case Fatality Rate Influenza

The data below comes directly from the RIVM website. I added the Cases for those weeks (from Nivel) and calculated the Case Fatality Rate (CFR).

Flu Season 2017/2018
RIVM: “In the winter of (2017/2018), mortality was increased for 15 weeks (week 51 2017 to 14 2018). The increased mortality coincided with the influenza epidemic that occurred from week 50 2017 to week 15 2018. Excess mortality during the 18 week influenza epidemic was estimated at 9,444“.

Case Fatality Rate Influenza 2017/2018
Number of reported cases at Nivel (week 51 2017 to 14 2018): 332,789.
9.444: 332.789 X 100% = CFR 2.84%.

Flu Season 2016/2017
RIVM: “In the winter of (2016/2017), mortality was increased for 12 weeks (week 48 2016 to 10 2017). The increased mortality started (week 46) 2 weeks after the flu epidemic started and lasted through the last week of the epidemic (excluding week 52 2016). During the 15-week influenza epidemic, excess mortality was estimated at 7,503“.

Case Fatality Rate Influenza 2016/2017
Number of reported cases at Nivel (week 46 2016 to 10 2017); 256,320.
7,503: 256,320 X 100% = CFR 2.93%

Flu Season 2015/2016
RIVM: “In the winter of (2015/2016), mortality was increased from weeks 1 to 14 of 2016 (excluding week 7). The increased mortality coincided with and lasted 3 weeks longer than the flu epidemic (which occurred from weeks 1 to 11). During the 11-week influenza epidemic, excess mortality was estimated at 3,900 deaths“.

Case Fatality Rate Influenza 2015/2016
Number of reported cases at Nivel (week 1 2016 to 11 2016); 211,588.
3,900 : 211,588 X 100% = CFR 1.84%

The Influenza Case Fatality Rate (CFR) is between 2.93% and 1.84%

Case Fatality Rate COVID-19

From week 10 to week 44 there were 339,030 reported COVID-19 cases (RIVM). And there were 7,321 deaths.

Case Fatality Rate COVID-19 2020
7,321 : 339,030 X 100% = CFR 2.15%

Some observations from the data

Flu Season 2017/2018: 9,444 Deaths in 18 weeks. Average: 525 per week.
Flu Season 2016/2017: 7,503 Deaths in 15 weeks. Average: 500 per week.
Flu Season 2015/2016: 3,900 Deaths in 11 weeks. Average: 355 per week.
COVID-19 2020: 7,321 Deaths in 34 weeks. Average: 215 per week.

According to the data:

  • COVID-19 is more contagious (if you ignore the test volume) than Influenza
  • Influenza is more deadly than COVID-19.

However this approach of interpreting the data completely ignores that the Humidity is lower in the Winter, compared to the spring, summer and autumn. So one can argue that the mortality of COVID-19 will be higher in the winter. But considering RIVM is ignoring Humidity, then the only conclusion you can draw is that COVID-19 is less deadly then the Flu.

So either the RIVM admits that Humidity plays an important role in infectivity, complications and even death or they have to admit COVID-19 is less dangerous than the Flu.

You can’t have your cake and eat it too! ‘-)

Edsard Ravelli