The National Center for Health Statistics (NCHS) collects and disseminates the Nation’s official vital statistics. \r\nNCHS collects death certificate data from state vital statistics offices for all deaths occurring in the United States. \r\nInfluenza deaths, pneumonia and/or influenza (P&I) deaths, and pneumonia, influenza and/or COVID-19 (PIC) deaths are identified based \r\non ICD-10 multiple cause of death codes.
NCHS Mortality Surveillance System data are presented by the week the death occurred at the national, \r\nstate, and HHS Region levels, based on the state of residence of the decedent. Data on the percentage of deaths due to influenza, P&I or PIC \r\nare released one week after the week of death to allow for collection of enough data to produce a stable percentage. States and HHS regions with \r\nless than 20% of the expected total deaths during a given week (average number of total deaths reported by week during 2008-2012) will be marked \r\nas having insufficient data for that week. Not all deaths are reported within a week of death therefore data for earlier weeks are continually \r\nrevised and the proportion of deaths due to influenza, P&I or PIC may increase or decrease as new and updated death certificate data are received \r\nby NCHS.
Three measures have been used to monitor influenza mortality: pneumonia and/or influenza (P&I); pneumonia, influenza, \r\nand/or COVID-19 (PIC); and influenza. Prior to the 2020-21 season, the NCHS surveillance data were used to calculate the percent of \r\nall deaths occurring each week that had pneumonia and/or influenza (P&I) listed as a cause of death. Because of the COVID-19 pandemic,\r\n COVID-19 coded deaths were added to P&I to create the PIC (pneumonia, influenza, and/or COVID-19) classification. PIC includes all deaths \r\nwith pneumonia, influenza, and/or COVID-19 listed on the death certificate.
Beginning with the 2023-24 season, in addition to P&I and PIC,\r\n there will be a shift to focus on the percent of all deaths with influenza listed on the death certificate. P&I does not measure the impact of \r\ninfluenza in the same way it did prior to the COVID-19 pandemic because the proportion of pneumonia deaths associated with influenza is now \r\ninfluenced by COVID-19-related mortality. Additionally, the PIC indicator is driven by COVID-19 more than influenza, making it difficult \r\nto monitor the impact of influenza using the PIC measure. Therefore, focusing on only influenza-related deaths will help to highlight \r\nand understand the impact of influenza on mortality.
The PIC and P&I percentages will continue to be shared on FluView Interactive.\r\n These percentages are compared to a seasonal baseline of P&I deaths that is calculated using a periodic regression model that incorporates a robust\r\n regression procedure applied to data from the four years prior to the COVID-19 pandemic (2015 week 10 through 2020 week 9) and \r\nthe 2022-2023 influenza season. An increase of 1.645 standard deviations above the seasonal baseline of P&I deaths is considered the\r\n “epidemic threshold,” i.e., the point at which the observed proportion of deaths is significantly higher than would be expected at that time of\r\n the year in the absence of substantial influenza and COVID-related mortality. Baselines and thresholds are calculated at the national and \r\nregional level and by age groups.
For more information on pneumonia and influenza mortality surveillance\r\n please visit: https://www.cdc.gov/fluview/overview/index.html#cdc_generic_section_5-mortality-surveillance
* \r\nThe 10 U.S. Department of Health and Human Services regions include the following jurisdictions. \r\nRegion 1: Connecticut, Main, Massachusetts, New Hampshire, Rhode Island, and Vermont; \r\nRegion 2: New Jersey, New York, and New York City; Region 3: Delaware, District of Columbia, Maryland, Pennsylvania, \r\nVirginia, and West Virginia; Region 4: Alabama, Florida, Georgia, Kentucky, Mississippi, North Carolina, South Carolina, \r\nand Tennessee; Region 5: Illinois, Indiana, Michigan, Minnesota, Ohio, and Wisconsin; Region 6: Arkansas, Louisiana, New Mexico, \r\nOklahoma, and Texas; Region 7: Iowa, Kansas, Missouri, and Nebraska; Region 8: Colorado, Montana, North Dakota, South Dakota, Utah, and \r\nWyoming; Region 9: Arizona, California, Hawaii, and Nevada; Region 10: Alaska, Idaho, Oregon, and Washington.
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