February 7, 2019

Influenza Surveillance Update – Alicia Budd (CDC)
2019 Recommended Adult Immunization Schedule – David Kim (CDC)
Other Items – L.J Tan (IAC)

Influenza Surveillance Update – Alicia Budd (CDC)

Alicia provided an update on influenza activity for week 4, ending January 26, 2019. Influenza activity remains elevated across the country, with several consecutive weeks of increasing activity.

For the week, 19% of specimens sent to clinical laboratories tested positive for influenza. This marks the third week for an increase in the percent positives. Influenza A (H1) remains the predominant strain reported from public health labs and in 9 of the 10 surveillance regions. Influenza H3 is still the predominant strain reported in Region 4 (southeastern states). H3 appears to be increasing slightly in other regions as well, but it is still too early to determine whether this is a changing trend. The amount of reported influenza B circulating viruses continues to remain very low, at approximately 3% for the season as a whole and approximately 1% for the week.

During this season, more than 700 viruses have received antigenic and genetic characterization. This data indicates the majority of viruses are similar to the reference viruses for this season’s vaccine components. In addition, more than 700 viruses have been tested for resistance to neuraminidase inhibitors. All viruses tested were susceptible to zanamivir, and >99% were susceptible to oseltamivir and peramivir. Four H1 specimens were found to have reduced susceptibility to oseltamivir and/or peramivir. Alicia noted that these rates were within normal expectations and have not increased concerns about resistance for this season.

Outpatient visits for influenza-like illness (ILI) increased during the week to 3.8%, up from 3.3% the previous week. We have now been at or above the national baseline for 10 consecutive weeks, and all 10 surveillance regions were above their region-specific baselines. On a state level, 23 states experienced high ILI levels, 10 states reported moderate activity, and the remaining 17 states were at low or minimal activity levels.

Cumulative reports to FluSurv-NET this season indicate a rate of 15.3/100,000 lab-confirmed influenza hospitalizations. Highest hospitalization rates were seen in persons >65 years at almost 40/100,000, followed by the 0–4 age group at 27/100,000.

The percent of deaths reported due to pneumonia and influenza (P&I) was equal to the epidemic threshold for the week. The current week reports indicate 7.2% of deaths were due to P&I.

Five new influenza-associated pediatric deaths were reported to CDC during the week. A total of 24 pediatric deaths have been reported to CDC this season. All but one of these reported cases for the season have been associated with influenza A virus infections, and the majority of the cases for which subtyping information was available have been influenza A (H1).

For the geographic spread of influenza during the week, 45 states reported widespread activity, 3 states reported regional activity, and 2 states reporting local or sporadic activity.

CDC is now updating preliminary in-season flu burden estimates each week. There have been at least 10.1 million influenza illnesses in the U.S. for this season. Approximately half of those persons have sought medical care, and at least 118,000 have been hospitalized. CDC will be adding mortality estimates to this report later in the season.

L.J asked if the vaccine match is as strong for H3 viruses as it is for H1. Alicia noted that there has been a fair amount of genetic diversity in this season’s H3 viruses, with 3 primary groups currently circulating. Approximately 43% of H1 viruses that have been genetically characterized have been similar to the vaccine clade. One of the circulating sub-clades is a different genetic group, but with some cross-reactivity to the vaccine. To date, 45 H3 viruses have received antigenic testing, and >95% of these have been similar to the vaccine. CDC will continue to monitor these changes.

2019 Recommended Adult Immunization Schedule – David Kim (CDC)

[Note: In addition to this discussion of the Adult Immunization Schedule, L.J reminded callers that the 2019 Recommended Child and Adolescent Immunization Schedule also has been published. This new schedule represents the “harmonized” recommendations (including the use of LAIV) from CDC, AAP, and AAFP.]

David provided a brief overview of the recently released 2019 Recommended Adult Immunization Schedule. (PDF for printing also available.) Three updates in ACIP recommendations are included in this schedule:

- Influenza – The 2019 schedule incorporates the reinstatement of LAIV as an option for influenza vaccination. This recommendation was approved by the ACIP in June 2018 and was previously published in August 2018. In addition to providing a recommendation for adults through age 49, the schedule includes information on populations who should not to receive this vaccine.

- Hepatitis B – In February 2018 ACIP recommended approval for a 2-dose regimen of Heplisav-B (recombinant hepatitis B vaccine) in adults age 18 or older. The minimum interval between doses is 4 weeks. This vaccine can be used to substitute for Engerix or Recombivax. Because of a lack of safety data, Heplisav-B is not recommended for use during pregnancy.

- Hepatitis A – During the October 2018 ACIP meeting, homelessness was included as an indication for routine use of hepatitis A vaccine. The schedule notes two doses of vaccine are recommended. A broad definition of “homeless” is based on the HHS National Healthcare for the Homeless Council. Therefore, some clinical judgment must be exercised to determine if someone is at risk.

Information on the use of vaccine in outbreak settings has been removed from the schedule, but web links to this information are included on the cover page. In addition, the table of Contraindications and Precautions has been removed. However, a web link is included for the General Best Practice Guidelines for Immunization, which contains information on contraindications and precautions.

Routine recommendations for adults by age are found in Table 1, while recommendations based on medical conditions or other indications are found in Table 2. Two new colors have been added to Table 2; orange for precautions (for LAIV and MenB) and pink for vaccinations which should be delayed until after pregnancy (for HPV and RZV.) Information that was formerly contained in the footnotes is now found in the “Notes” section, with vaccines listed in alphabetical order.

David noted that questions or comments on the new schedule format may be submitted online or by calling 800-CDC-INFO (800-232-4636).

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.