Influenza Surveillance Update – Alicia Budd (CDC)
Alicia provided an update on influenza activity reported for week 6, ending February 9, 2019. Influenza activity continued to increase across the country.
For the week, 24.6% of specimens sent to clinical laboratories tested positive for influenza. This is an increase from the percentage reported during the previous week. Influenza A (H1) remains the predominant strain reported from public health labs and in 9 of the 10 surveillance regions. Influenza H3 was the predominant strain reported in Region 4, and an increasing percentage of H3 reports are being received from all regions. Looking at reports from the last three weeks, Regions 6 and 7 are now reporting approximately equal amount of H1 and H3 viruses. The amount of reported influenza B circulating viruses continues to remain remarkably low.
During this season, almost 1,000 viruses have received antigenic and genetic characterization. All of the H1 viruses are the 6B clade, though there is some genetic diversity within the clade. In spite of this diversity, 99% of H1 viruses tested are similar antigenically to the cell-propogated vaccine virus. Three subclades of H3 virus are co-circulating, with the 3C.3a subclade continuing to increase. This subclade is not antigenically similar to the vaccine. All of the Influenza B Yamagata viruses tested have belonged to the Y3 clade and are similar to the vaccine. For the Victoria viruses, co-circulation of several viruses is occurring, but the majority (71%) are similar to the V1A.1 reference virus. Almost 1,000 viruses have been tested for resistance to oseltamivir, peramivir, and zanamivir. Of these, four H1 specimens have been found to have reduced susceptibility to oseltamivir and peramivir.
Outpatient visits for influenza-like illness (ILI) increased during the week to 4.8%. We have now been at or above the national baseline for 10 consecutive weeks. All 10 surveillance regions were above their region-specific baselines. On a state level, 26 states experienced high ILI levels, 8 states reported moderate activity, and the remaining 13 states were at low or minimal activity levels.
Cumulative reports to FluSurv-NET this season indicate a rate of 23.8/100,000 lab-confirmed influenza hospitalizations. Highest hospitalization rates were seen in persons >65 years at almost 64.1/100,000, followed by the 0–4 age group at 36.8/100,000.
The percent of deaths reported due to pneumonia and influenza (P&I) is below the epidemic threshold. The current week reports indicate 7.0% of deaths were due to P&I.
Six new influenza-associated pediatric deaths were reported to CDC during the week, bringing the total number of deaths reported this season to 34. Half of these deaths were associated with H1 infection, 9% with H3 infection, 38% with an influenza A virus infection which was not subtyped. One death was associated an influenza B virus.
For the geographic spread of influenza during the week, 48 states reported widespread activity, 1 state reported regional activity, and 1 state reporting local or sporadic activity.
For the preliminary influenza burden reports released, an estimated 15.4–17.8 million persons have been ill with flu. Approximately half of those persons have received medical care, and 181,000–221,000 were hospitalized.
Other Items – L.J Tan (IAC)
- 2019 Summit In-Person Meeting Information Now Available Online – The 2019 Summit in-person meeting will be held in Atlanta, GA on May 14–16, 2019. Information on registration, submission of poster abstracts, and nominations for the 2019 Immunization Excellence Awards is available on the 2019 National Adult and Influenza Immunization Summit webpage. (Please note that the password to register for this invitation-only meeting is available by contacting L.J Tan.) If possible, please book your room either through the onscreen “pop-up” that appears after you register or later through the email you receive after completing your registration. This not only will give you access to the “preferred rate,” it also will help the Summit meet its lodging contractual agreement with the hotel.
- 2019 Immunization Excellence Awards and Poster Submissions – The deadline for nominations has been extended through March 1. Awards will be given in five categories. In particular, L.J called attention to the Non-Healthcare Employer Campaign Award, as many Summit partners might be aware of deserving nominees in this category. Nominations may be made online via the Summit website. The Summit also is accepting abstracts for poster presentations at the meeting.
- ACIP Meeting – The ACIP meeting will be held on February 27–28. Therefore, there will be no Summit call on February 28.