Here something from the CDC I am having trouble understanding.
Check this out (bolded and underlined) are the parts I am getting confused on - didnt want to take the sentences out of context (reason for big copy-paste)
& here is the link to the full CDC publication/page -
https://www.cdc.gov/flu/weekly/overview.htm
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5. Mortality Surveillance
National Center for Health Statistics (NCHS) mortality surveillance data – NCHS collects death certificate data from state vital statistics offices for all deaths occurring in the United States and are aggregated by the week of death occurrence.
Deaths are classified based on ICD-10 multiple cause of death codes as associated with influenza, COVID-19, or pneumonia. To allow for collection of enough data to produce a stable percentage, NCHS surveillance data are released one week after the week of death and percentages for earlier weeks are continually revised and may increase or decrease as new and updated death certificate data are received by NCHS.
In previous seasons, the NCHS surveillance data were used to calculate the percent of all deaths occurring each week that had pneumonia and/or influenza (P&I) listed as a cause of death.
Because of the ongoing COVID-19 pandemic, COVID-19 coded deaths were added to P&I to create the PIC (pneumonia, influenza, and/or COVID-19) classification. PIC includes all deaths with pneumonia, influenza, and/or COVID-19 listed on the death certificate. Because many influenza deaths and many COVID-19 deaths have pneumonia included on the death certificate, P&I no longer measures the impact of influenza in the same way that is has in the past. This is because the proportion of pneumonia deaths associated with influenza is now influenced by COVID-19-related pneumonia. The PIC percentage and the number of influenza and number of COVID-19 deaths will be presented in order to help better understand the impact of these viruses on mortality and the relative contribution of each virus to PIC mortality.