March 29, 2018

March 29, 2018

Influenza Surveillance and ACIP Influenza Update – Alicia Budd (CDC)

Alicia provided highlights of the influenza surveillance report from week 11, ending March 17, 2018. All indicators are continuing to show a decline in flu activity levels.

The percentage of respiratory specimens testing positive for influenza in clinical laboratories was 15.5%. Positive specimens continue to be trending downward for influenza A, while influenza B showed a very slight increase from the previous week. Data from public health laboratories indicates influenza B accounted for more than one-half the reports from those facilities. For the season as a whole, influenza H3N2 is the predominant virus. Almost 30% of the positive influenza A specimens were H1.

Specimens characterized since May continue to be antigenically and genetically similar to the reference virus for this season’s vaccine. For H3, H1, and B Yamagata viruses, 98–100% are similar to their respective cell-grown viruses. However, the egg-grown viruses have a lower similarity to the vaccine virus for H3. In addition, a growing subset of the B Victoria viruses have a particular genetic change and amino acid deletion that affects their antigenic similarity to the vaccine.

A total of nine (9) H1 specimens have been found to be antiviral resistant this season. This is still quite low, occurring with just over 1% of the H1 specimens tested. No antiviral resistance has been detected for H3 or B viruses.

Nationwide, influenza-like illness (ILI) activity was at 2.7%, down from the 3.2% reported in the prior week. Although we are still above the baseline of 2.2%, this is the sixth consecutive week we have seen a decline in this system. One HHS region (Region 6) is now below baseline levels for ILI activity, while the other 9 regions remain above baseline. ILI information also is available on a state level, with activity summarized as high, moderate, low, or minimal. Last week, 6 states reported high ILI activity; 9 states reported moderate ILI activity; 17 states and New York City, Puerto Rico, and the District of Columbia reported low ILI activity; and 18 states reported minimal ILI activity.

Information from the Influenza Hospitalization Surveillance Network (FluSurv-NET) indicates an overall hospitalization rate of 93.5 per 100,000 population. The highest rate (401.8 per 100,000) was among adults age >65 years, followed by adults age 50–64 (101.5 per 100,000 population) and children age 0–4 (66.4 per 100,000).

Five (5) new influenza-associated pediatric deaths were reported during week 11. For the 2017–2018 season, the total number of reported pediatric deaths is 133. Approximately one-third of these deaths were associated with influenza B viruses. Of the deaths associated with influenza A viruses, about ½ were associated with H1.

In terms of geographic spread of influenza within a state (characterized as widespread, regional, local, sporadic, or no activity) as reported by state and territorial epidemiologists, 17 states reported widespread activity; 26 states, Guam, and Puerto Rico reported regional activity; 5 states and the District of Columbia reported local activity; 2 states and the Virgin Islands reported sporadic activity; and 0 states and the U.S. Virgin Islands reported no influenza activity.

Announcements – LaDora Woods (CDC)
  • LaDora reminded partners that they should register for the Summit meeting being held May 17­–18 in Atlanta, Georgia. Individuals needing the password to register for the meeting should contact L.J Tan. Partners also are reminded to register for the National Immunization Conference (NIC) to be held immediately prior to the Summit meeting.
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