Impact of Laboratory Reporting of Influenza on Flu Surveillance in Arizona Laura Erhart, Shoana Anderson, Kelly Scranton Arizona Department of Health Services National Immunization Conference March 9, 2006

Arizona influenza surveillance Traditional components: Influenza-like illness (ILI) sentinel surveillance Sub-typing at the State Laboratory Weekly calls to three clinical laboratories Reports of flu activity & outbreaks from hospitals, doctors, county health departments

Rule changes 2004 Directors of clinical laboratory, or their representatives, must submit reports of positive influenza virus test results to the Arizona Department of Health Services within five working days. Report should include: name, DOB, collection date, type of test, test result, provider’s name and phone number. Reporting is from LABS, not PROVIDERS

Objective To describe the impact of mandatory laboratory-reporting of influenza on surveillance and communications during the 2004-2005 and 2005-2006 influenza seasons.

Influenza-like illness

State lab data: culture & PCR

Laboratory reporting Note scale for 2005-06 is 10x 2004-05

Geographic representation

“Statewide” surveillance: ‘05-’06 Enrolled ILI sites Regular reporters 2004-2005 season is similar

“Statewide” surveillance: ‘04-’05 State lab positives County Other lab reports Apache 21 6 Coconino 61 Gila 5 Graham 156 3 Navajo 11 2 Pima 223 Pinal 16

“Statewide” surveillance: ‘05-’06 State lab positives County Other lab reports 1 Apache 51 4 Coconino 180 Gila 66 Graham 183 Navajo 45 20 Pima 395 Yuma 35

Data concordance

2004-2005 ILI somewhat weak signal

2004-2005

2004-2005

2004-2005

2005-2006

2005-2006

2005-2006

2005-2006

Discussion

Beginning of season Rapid tests filled in gaps when otherwise might have gone down to “no activity” Positive rapid tests reported both seasons before first culture-confirmed ADHS decision to call beginning of season based on culture-positive case Rapid tests then “count”

Middle of season Lab reports show similar trends to ILI, state lab, and sentinel lab data Provide greater confidence for decisions & public health responses Provide greater geographic representation Fill in gaps in otherwise-limited data In past, relied on anecdotal clinical reports for when activity was “bad”; now have more solid, passive data

End of season Difficult to determine when season ends Lab tests trickled in through June 2005, sporadic reports throughout summer Some state lab cases through May/June Reporting of “sporadic” activity extended Are we detecting low levels of cases? or lots of false positive rapid tests?

What’s in a number? Current context of media/public wanting to know how many cases of X we have ADHS can now provide counts of lab-confirmed flu cases BUT: Is this the correct message when discussing flu & flu surveillance? Focus on the numbers rather than that flu surveillance is an indication of what is going on in the community.

Resources Data entry! First season manageable Second season difficult Mild season (2004-2005) Reporting was new – all labs reporting? Second season difficult Staff time, data entry sometimes lagged Data entry temp hired partway through season Need electronic lab reporting

Other topics for consideration Using collection date (proxy for diagnosis or onset) vs. date reported Rapid vs. culture tests: Balance between more comprehensive reporting and chance for false positives Need to weigh type of test in evaluating activity? Reports may be from any source: no differentiation of severity

More considerations Do communications that flu has arrived (or is widespread) affect testing and thus what is reported? Might some providers decide to test more for flu once it’s announced that “flu season has arrived”? Or decide to start treating without testing midseason?

Determining activity levels CDC activity levels do not account for lab reporting Definitions focus on institutional outbreaks and ILI activity Reporting of institutional outbreaks is tepid for AZ ILI has not proven sensitive in recent years Increasing usage of patterns indicated through laboratory data

Conclusions Lab-reporting of influenza has led to more comprehensive flu surveillance and better understanding of community activity Facilitated communications and confidence in timing public health responses Resource drain is a limitation if electronic lab reporting is not available.