April 26, 2018

April 26, 2018

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

Alicia provided highlights of the influenza surveillance report from week 15, ending April 14, 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 just under 11%. Positive specimens for both influenza A and B are considerably lower than peak levels and continue to decline. During week 15, influenza B was the most predominantly reported virus. Approximately 90% of the B viruses seen this season are of the Yamagata lineage. Of the influenza A viruses recently reported, approximately 40% are H1 and 60% are H3. For the season as a whole, influenza H3N2 is the predominant virus.

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 ten (10) 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 has continued to decline during weeks 14 and 15, and activity fell below the baseline of 2.2% during week 14 for the first time. During week 15, reported ILI activity was at 1.8%. Nine of the ten HHS regions reported being below baseline levels for ILI activity, while the other 7 regions remain above baseline. ILI information also is available on a state level, with activity summarized as high, moderate, low, or minimal. Last week, 1 state (Arizona) reported high ILI activity; 2 states (Alaska and South Dakota) reported moderate ILI activity; 6 states reported low ILI activity; and 41 states, New York City, the District of Columbia, and Puerto Rico reported minimal ILI activity.

Information from the Influenza Hospitalization Surveillance Network (FluSurv-NET) indicates an overall hospitalization rate of 103.7 per 100,000 population. The highest rate (446.4 per 100,000) was among adults age >65 years, followed by adults age 50–64 (112.8 per 100,000 population) and children age 0–4 (72.7 per 100,000).

The percent of deaths attributed to pneumonia and influenza (P&I) during week 15 declined to 7.1%, which is below the epidemic threshold of 7.2%.

Nine (9) new influenza-associated pediatric deaths were reported during week 14, and five (5) were reported during week 15. For the 2017–2018 season, the total number of reported pediatric deaths is 156. Approximately one-third of these deaths were associated with influenza B viruses. Of the deaths associated with influenza A viruses, about half 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, 5 states reported widespread activity; 16 states, Guam, and Puerto Rico reported regional activity; 21 states reported local activity; 6 states and the District of Columbia reported sporadic activity; and 2 states and the Virgin Islands reported no influenza activity.

Announcements – Amy Parker Fiebelkorn (CDC)

NVAC Meeting – L.J announced that NVAC will hold a special 2-hour meeting of the HPV Implementation Workgroup on May 3. The normal 2-day meeting previously scheduled for June 3-4 has now been shortened to a 1-day meeting on June 5. This meeting will be held only by teleconference, i.e., it will not be an in-person meeting.

Print Friendly, PDF & Email