October 11, 2018

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October 11, 2018

Influenza Surveillance in the United States – Alicia Budd (CDC)

Alicia provided a presentation on the components of the national influenza surveillance system in the U.S. This overview is particularly timely as we move into a new influenza season.

The national influenza surveillance system was constructed many years ago to give us information such as what viruses are circulating, novel viruses that may have been identified, provide situational awareness about the current season, monitor severity of the season, and describe clinical infection and those at risk. All of this information is utilized to guide decisions for interventions.

The system is a collaborative effort between CDC, state and local public health partners (including public health laboratorians), and data providers such as clinicians, vital statistics staff, and clinical laboratorians. Data for the national surveillance system is received from 8 sources: 3 have to do with the virus itself, 2 are related to influenza-associated mortality, and 1 each with outpatient influenza-like illness (ILI), hospitalization, and geographic spread. All of this information is reported to CDC, which summarizes the data and feeds it back out to public health partners and the general public.

CDC’s weekly surveillance report is distributed via FluView and FluView Interactive. FluView is a static report, while FluView Interactive allows the user to see more detail such as geographic breakdowns, seasonal variations, etc.

Alicia described the timeliness of the influenza data that is reported. Weeks run from Sunday through Saturday. Information for the previous week is reported on Monday and Tuesday of the following week. CDC then compiles the data on Wednesday and Thursday for release on Friday morning.

Three sources of data comprise the virologic surveillance: (1) WHO Collaborating Laboratories, (2) National Respiratory and Enteric Virus Surveillance System Laboratories (NREVSS, and (3) Novel Influenza A Reporting. Approximately 100 public health laboratories and 300 clinical laboratories participate in the reporting. On a weekly basis, these labs submit information about the number of specimens tested and the number positive by type and subtype. This analysis helps in assessments of whether activity is increasing or decreasing, the distribution of circulating viruses, and the identification of viruses with pandemic potential.

Laboratory from clinical laboratories and public health laboratories is compared. Analysis of information from both types of labs is important because public health lab specimens may have been solicited in response to symptoms, which could make the results artificially high. To date, influenza A is predominant. Of the influenza B specimens tested, all have been B Victoria.

A subset of influenza positives are submitted to CDC for additional testing, including full genome sequencing, detailed antigenic characterization, antiviral resistance testing, and development of vaccine candidate strains, as needed.

Alicia discussed a graph of novel influenza A viruses in the U.S. These have all been variant strains except for the 2001–2012 season. Whenever a novel virus is reported, CDC conducts a full review and investigation.

Approximately 2,500 primary care providers from all 50 states participate in the influenza-like illness (ILI) surveillance. Last season more than 47 million patient visits were captured. The data is used to determine elevated activity, timing of increased activity, and the intensity of the peak.

In the 2017–2018 season, peaks were nearly as high as were seen in the pandemic. Last week, 1.2% of visits were for ILI. The ILI intensity map of the country will begin being published next week.

FluSurv-Net looks at the rate of laboratory confirmed influenza and related hospitalizations. It covers about 9% of the U.S. population. Data is obtained on laboratory information, pre-existing conditions, and the clinical course of the disease. This information is compared between seasons. The 2017–2018 data was record-breaking, with 103 hospitalizations/100,000. These data also are available on FluView Interactive by age group.

Two methods are used to compile mortality data. Information is collected from the National Center for Health Statistics (NCHS) mortality data system. Death certificates are reviewed for pneumonia- or influenza-related deaths on a weekly basis. In previous weeks, this data lagged by 2 weeks. Due to efforts of NCHS, this data will have only a one week lag in the future. In addition, a database is maintained for Influenza-Associated Pediatric Mortality. States report information on deaths in persons younger than 18 years. For the 2017–2018 season, the total number of pediatric deaths is 181. The most recent death occurred at the end of September and was associated with influenza B.

The State and Territorial Epidemiologists Report is a marker of the geographic spread (not intensity) of flu activity in the states. This component doesn’t operate in the summer.

In summary, the U.S. National Influenza Surveillance System:

  • Is a multi-component system that provides indicators of
    • Where, when and to what extent influenza activity is occurring and
    • Which viruses are responsible for that activity
  • Requires participation of many partners –healthcare, public health
  • Is NOT trying to count every case of influenza or influenza-related illness
    • Data from each component is analyzed/reported in way that most appropriately allows comparison from season to season
    • Can only compare case counts for novel influenza A and pediatric death
  • Ultimate goal: Provide data needed to guide public health and clinical decision making in order to minimize the impact of influenza

Finally, Alicia pointed out specific (and frequently confused) resources:

  • Vaccine Availability
    • Flu Vaccine Finder (www.vaccinefinder.org)

NFID News Conference Summary – Marla Dalton (NFID)

Marla provided a presentation about the 2018 NFID Influenza and Pneumococcal News Conference that was held on September 27 at the National Press Club in Washington, DC. The conference, which is held in collaboration with CDC, serves as the official kickoff to the upcoming flu season and provides a forum to share public health priorities for the coming season.

Panelists for this year’s conference were:

  • William Schaffner, MD, NFID Medical Director (moderator)
  • Jerome Adams, MD, MPH, U.S. Surgeon General (keynote speaker)
  • Wendy Sue Swanson, MD, MBE, Pediatrician and Chief of of Digital Innovation at Seattle Children’s Hospital (representing the American Academy of Pediatrics)
  • Laura Riley, MD, Given Foundation Professor and Chair of the Ob-Gyn Department at Weill Cornell Medicine (representing the American College of Obstetricians and Gynecologists)

The panelists shared CDC’s final vaccination coverage rates from the 2017–2018 season for children, pregnant women, and healthcare providers. (The final data for adults in the general population is not yet available.) In light of the severity of influenza last season, the panelists emphasized the importance of protecting children and highlighted the need for flu vaccination during pregnancy, and with a special emphasis reviewing the dangers of influenza and pneumococcal disease for those with chronic health conditions.

Several key influencers joined the Surgeon General in receiving flu shots during this year’s “Leading by Example” program. Scott Gottlieb, MD, FDA Commissioner and Joe Thomas, former Cleveland Brown’s player and 2006 Outland Trophy Winner, were vaccinated during the media event.

The event generated enthusiasm among both the media and the immunization community at large. This year’s attendance broke records, with more than 25 advocacy partner groups onsite and 400 on-line participants. To date, more than 50 original print, online, and broadcast stories have been generated by the event, with an estimated reach of >575 million impressions. All of this coverage has included at least one of the key messages shared at the event. Nearly 50 vaccines were administered at the onsite clinic provided by MedStar Visiting Nurses Association. Social media activities also played a large hand in publicizing the event. More than 3,000 tweets were posted using the hashtag #fightflu.

A recording of the conference and a full transcript are available on the NFID website. Marla encouraged partners to participate in the Leading by Example initiative. All that is required is submission of a photo of a key partner’s leadership receiving flu vaccine. The photo will be included in NFID’s Leading by Example gallery.

Marla noted that the last slide in her presentation contains 3 ways partners can help fight flu, including the traveling flu bug. She also thanked all partners for their continued participation in the event.

In response to a question, Marla noted that they have begun partnering with the NFL in several ways to provide outreach. This is an exciting new opportunity, and L.J expressed enthusiasm for the Summit’s participation in these events as the partnership flourishes.

Influenza Vaccine Effectiveness in Prevention Flu-Associated Hospitalizations during Pregnancy – Mark Thompson (CDC)

Dr. Thompson provided a presentation on the article published this morning in Clinical Infectious Diseases, Influenza Vaccine Effectiveness in Preventing Influenza-Associated Hospitalizations during Pregnancy: A Multi-Country Retrospective Test Negative Design Study, 2010-2016. He noted that, although he is the lead author, this article is the result of a collaboration of a large team of researchers.

As is well known, pregnant women are at increased risk of severe influenza disease, including influenza hospitalization. Although studies have provided evidence that IIV is effective in mild to severe influenza illness, there has been a gap in evidence for influenza vaccine effectiveness (IVE) in preventing influenza-associated hospitalizations during pregnancy. Therefore, CDC funded the Pregnancy Influenza Vaccine Effectiveness Network (PREVENT) to create a collaboration of partners to study this issue.

The study included information from 4 countries and over 2 million pregnancies. Of these, 1,030 women were identified with acute respiratory or febrile illness; 58% were PCR-flu positive. Across all sites, 16% of the hospitalized women were vaccinated.

The IVE (adjusted for site, season, season timing, and high risk medical conditions) was 40%. This rate was higher in the U.S. than in other participating countries.

In summary, there is a substantial hidden burden of influenza virus infection among hospitalized pregnant women. Because 84% of pregnancies overlap with the influenza season, most pregnant women are exposed to flu during pregnancy. Importantly, the study indicated influenza vaccines had the potential to prevent 40% of influenza-associated hospitalizations during pregnancy. This information further strengthens international recommendations that pregnant women get a flu shot during any trimester.

CDC has issued a press release on this important study.

Other Items – L.J Tan (IAC)
  • Summit Call Schedule – L.J reminded partners that the Summit calls have now returned to a weekly schedule, unless otherwise cancelled. Calls are held on Thursdays at 3 p.m. ET.
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