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Respiratory Viruses

This guide covers viral respiratory infections, including influenza, RSV, and other influenza-like illnesses (ILI)

U.S. Weekly Influenza Report

Weekly U.S. Influenza Surveillance Report
Updated: March 8, 2024
Key Updates for Week 9, ending March 2, 2024
  • Seasonal influenza activity remains elevated nationally with increases in some parts of the country.
  • Nationally, percent positivity for influenza remained stable compared to last week. Trends in percent positivity for influenza A and B varied by region.
  • Nationally, outpatient respiratory illness declined slightly but remains above baseline. Regions 8 and 10 are below their respective baselines during Week 9 for the first time since early and mid-November, respectively, while the remaining HHS regions remain above their respective baselines.
  • The number of weekly flu hospital admissions remained stable compared to last week. After five weeks of sharp decline between late December and early February, the number of weekly flu hospital admissions has been trending downward slightly since mid-February.
  • During Week 9, of the 615 viruses reported by public health laboratories:
    • 437 (71.1%) were influenza A
    • 178 (28.9%) were influenza B
  • Of the 286 influenza A viruses subtyped during Week 9:
    • 164 (57.3%) were influenza A(H1N1)
    • 122 (42.7%) were A(H3N2)
  • Ten influenza-associated pediatric deaths were reported during Week 9, bringing the 2023-2024 season total to 103 pediatric deaths.
  • CDC estimates that so far this season, there have been at least:
    • 28 million illnesses
    • 310,000 hospitalizations
    • 20,000 deaths from the flu
  • CDC recommends that everyone 6 months and older get an annual flu vaccine.
  • There also are prescription flu antiviral drugs that can be used to treat flu illness; those should be started as early as possible and are especially important for higher risk patients.
  • Influenza viruses are among several viruses that contribute to respiratory disease activity. CDC is providing updated, integrated information about COVID-19, influenza, and RSV activity on a weekly basis.
Updates to U.S. Flu Surveillance Methods for the 2023-2024 Season
  • Starting with the 2023-2024 influenza season, the percentage of deaths with influenza listed on the death certificate will be displayed in FluView.
  • P&I (pneumonia and/or influenza) no longer measures the impact of influenza in the same way it had prior to the COVID-19 pandemic, and the PIC (pneumonia, influenza and/or COVID) measure is largely being driven COVID-19 activity making it difficult to monitor the impact of influenza using that measure.
  • Although monitoring influenza-only coded deaths will underestimate the full impact of influenza mortality, this measure allows for tracking trends in the impact of influenza on mortality and is not as influenced by COVID-19 as the other two measures.
  • More information about U.S. influenza surveillance is available.

New York State Weekly Influenza Report

The New York State Department of Health (NYSDOH) conducts seasonal flu surveillance from October through May. Note: In view of persisting elevated influenza activity throughout NYS, NYSDOH is extending the surveillance season beyond May until influenza activity has decreased.

Data are updated weekly on Friday by 5 pm during the surveillance season. The data represents counts of persons with laboratory-confirmed influenza (“cases”) and counts of persons with laboratory-confirmed influenza who are hospitalized (“hospitalizations”) and are reported to the NYSDOH. Weekly and season-to-date data are displayed for the current and prior flu seasons.

NYSDOH Weekly Influenza Surveillance Report

During the week ending March 2, 2024:

  • Influenza activity was categorized as geographically widespread*. This is the 14th consecutive week of widespread activity reported this season.
  • Laboratories tested 46,621 specimens for influenza, of which 17,548 (38%) were positive, an 8% decrease in positive cases compared with the previous week.
  • The number of patients hospitalized with laboratory-confirmed influenza was 1,085, an 8% decrease in hospitalized cases compared with the previous week
  • Of the 4,825 specimens submitted to WHO/NREVSS laboratories:
    • 711 (15%) were positive
      • 431 positive for influenza A
      • 280 positive for influenza B
  • The percent of patient visits for influenza-like illness (ILI) from ILINet providers was 2.22%, below the regional baseline of 4.20%.
  • There were 11 outbreaks reported in hospitals and 18 outbreaks were reported in nursing homes.
    • Season to date, there have been a total of 680 outbreaks reported from hospitals and nursing homes in NYS.
  • There were no influenza-associated pediatric deaths reported this week. There have been 11 influenza-associated pediatric deaths reported this season.
New York State (including NYC) Laboratory Confirmed Influenza Reports

Last Updated: Week 9, ending March 2, 2024

New York State Regional Influenza Activity

Last Updated: Week 9, ending March 2, 2024

  • 62/62  counties reported influenza cases this week
  • Incidence ranged from 21.20 to 206.14 cases / 100,000 population

*NYS Influenza Activity Levels

No Activity: No laboratory-confirmed cases of influenza reported to the NYSDOH.
Sporadic: Small numbers of lab-confirmed cases of influenza reported.
Local: Increased or sustained numbers of lab-confirmed cases of influenza reported in a single region of New York State; sporadic in rest of state.
Regional: Increased or sustained numbers of lab-confirmed cases of influenza reported in at least two regions but in fewer than 31 of 62 counties.
Widespread: Increased or sustained numbers of lab-confirmed cases of influenza reported is greater than 31 of the 62 counties.
Increased or sustained: Two (2) or more cases of laboratory-confirmed influenza per 100,000 population

New York City Weekly Influenza Report

The New York City Department of Health and Mental Hygiene (DOHMH) collects, compiles, and analyzes information on respiratory virus activity year-round in New York City (NYC) and produces this weekly report on influenza (flu) and respiratory syncytial virus (RSV) during October through May.

New York City Weekly Influenza & RSV Surveillance Report
Week 9, ending March 2, 2024
  • 6,733 specimens were positive for influenza, a 9% decrease from the previous week
    • 63% were positive for influenza A
    • 36% were positive for influenza B
  • 573 specimens were positive for RSV, a 3% increase from the previous week
  •  Influenza-like illness visits were at 7% of all weekly visits
  • There were no influenza-associated pediatric deaths reported. Season to date, a total of five influenza-associated pediatric deaths have been reported.
  • There were eight influenza outbreaks reported from long-term care facilities. Season to date, a total of 147 outbreaks have been reported.
NYC Laboratory-Confirmed Influenza Reports by Season

All clinical laboratories that perform testing on NYC residents report positive influenza test results electronically to DOHMH. Differences across seasons in the volume of positive influenza laboratory reports reflect changes not only in the volume of infections, but also in patient care seeking and laboratory testing and reporting practices.