May 23, 2019

May 23, 2019

Influenza Surveillance Update – Alicia Budd (CDC)

Alicia provided an update on influenza activity reported for week 19, ending May 11, 2019. Influenza activity is finally decreasing across the country.

For the week, 3.7% of specimens sent to clinical laboratories tested positive for influenza. There were no real changes from previous weeks in the proportion of influenza subtypes identified. This has been a predominantly influenza A (H1) season overall, but H3 has been the most frequently reported virus from February onward. The amount of reported influenza B circulating viruses continues to remain very low.

During this season, more than 2,600 viruses have been genetically or antigenically characterized. The proportions of particular genetic groups being seen now aren’t changing because the numbers being submitted are so small. The majority of the H1, B Victoria, and B Yamagata viruses are all similar genetically and antigenically to this season’s vaccine. However, the 3C3a subclade of the H3 virus is different from the vaccine. Fifty-six percent (56%) of the H3 viruses have reacted poorly to the egg-grown reference virus.

Over 2,500 viruses have been tested for resistance to oseltamivir, peramivir, and zanamivir. A total of 6 H1 specimens have now been found to have reduced or highly reduced inhibition by oseltamivir and peramivir. However, more than 99% of tested viruses have been susceptible to antiviral medications. No viruses have been identified this season that were resistant to zanamivir.

Outpatient visits for influenza-like illness (ILI) declined to 1.6%, a drop for the third consecutive week, and all 10 surveillance regions were below their region-specific baselines. On a state level, Kentucky and Puerto Rico were experiencing low ILI activities, while the remaining 49 states and New York City reported minimal activity.

Hospitalization rates are unchanged because FluSurv-NET discontinued enrolling patients for this season on April 30. However, there may be slight variations in previously reported numbers as data cleaning continues throughout the summer. At 5.6%, the percent of deaths reported due to pneumonia and influenza (P&I) was below epidemic thresholds. P&I has been relatively low for the entire season, with only 10 weeks slightly above threshold levels.

A total of 109 influenza-associated pediatric deaths were reported to CDC during this season. The majority of these deaths were due to influenza A. For those with subtype information available, 67% were H1 and 33% were H3.

For the geographic spread of influenza during the week, no states reported widespread activity, 4 states reported regional activity, and the majority of states reported local or sporadic activity. Two states reported no influenza activity.

The end-season influenza burden reports (note: these will still be adjusted as additional data is received) indicate For the preliminary influenza burden reports released, an estimated 37.4–42.9 million persons have been ill with flu, 17.3–20.1 million have had a medical visit, and approximately 531,000–647,000 persons have been hospitalized. An estimated 36,400–61,200 flu-related deaths have occurred.

The final full FluView report for the season will be posted on May 24. However, an abbreviated version will be released weekly throughout the summer.

Hepatitis A Outbreak Response – Neil Gupta (CDC)

Dr. Gupta provided a brief presentation on the response to the nation’s ongoing hepatitis A outbreak. Typically, the United States is a low endemicity country. During the pre-vaccine era, >21,000 cases were reported annually, with cyclical increases occurring every 10–15 years. Since the introduction of vaccine, the number of cases has reduced dramatically. However, since 2016 we are seeing an unprecedented increase in the number of hepatitis A infections. From 2016–2018, >17,500 outbreak-associated cases have been reported.

In the past, outbreaks were primarily associated with asymptomatic children. Recent outbreaks are affecting primarily adults and are causing severe disease. Infections are occurring in different populations in different parts of the country, but they are largely among persons using drugs, those who are homeless, or men having sex with men (MSM). Because of the populations being affected, we are seeing high rates of coinfection with hepatitis B and C. The hospitalization rates among reported cases are also higher than in the past, with 9,900 (57%) of persons being hospitalized and 175 deaths occurring. This high hospitalization rate has resulted in an estimated millions of dollars in healthcare costs. The cases are occurring primarily among persons using drugs, likely related to person-to-person contact, as well as crowding and poor hygiene.

Dr. Gupta provided maps comparing hepatitis A incidence between 2015 and 2018. The 2018 map shows a good bit of activity along Appalachia. The highest incidence has been in West Virginia, with 112/100,000 population.

Vaccination is the cornerstone for control of community outbreaks. However, post-exposure prophylaxis alone may not effectively control outbreaks. Targeted vaccination to groups at highest risk are the best way to control disease spread, and outbreak programs are required from many disciplines within public health. States that have been most successful at controlling outbreaks have launched targeted vaccination programs for high risk populations, including those at syringe service programs, homeless shelters, and substance abuse treatment centers. One area showing success has been outreach to incarceration centers, particularly county jails. Peer mentors are critical partners in improving vaccine outreach. These individuals often have the “soft skills” needed to engage vulnerable populations most at risk.

Dr. Gupta described multiple activities being conducted by CDC in response to the hepatitis A outbreak, including maintaining national situational awareness through surveillance, establishing guidance to assit state and local health departments, cultivating communication and coordination between internal and external partners, facilitating sharing of best practices among health departments, and supplementing state/local resources to maintain robust outbreak response activities.

CDC holds bi-weekly regional calls with impacted states to review epidemiology, provide guidance, and discuss best practices for vaccine ordering, storage, and administration issues. The agency also conducts outreach to state health leaders/policy makers and provides technical assistance as needed. CDC also works closely with states to support vaccine supply and distribution, particularly with Section 317 vaccine.

Multiple resources are available on CDC’ Hepatitis A Outbreak website. Dr. Gupta requested persons needing additional resources or information should contact CDC.

Other Items – L.J Tan (IAC)
  • 2019 Summit In-Person Meeting Information Now Available Online – The presentations and bios of presenters from the 2019 Summit In-Person Meeting are now available on the Summit website, except for presentations for which permission to post has not yet been received. Keep checking the site for updates as additional presentations are loaded. In addition, the site now includes the excellent posters presented at the meeting, as well as information and photos from the 2019 Immunization Excellence Awards luncheon. Future additions to the site will provide updates on workgroup discussions and answers to questions received during the influenza hot topics discussion. Stay tuned!
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