H1N1 COUNTERMEASURES STRATEGY AND ... - PHE Home

NBSB Pandemic Influenza Working Group
Detailed Report
95 laboratories in the United States, 15 DoD laboratories internationally, and 250 other
laboratories internationally. More than 600 genes have been sequenced.
The enhanced virologic surveillance demonstrated that seasonal influenza continues to
occur longer than public health officials thought. Dr. Jernigan pointed out that even poor
surveillance efforts can provide useful data if they are consistent.
Initially, testing was recommended for any suspicion of H1N1, but the rapid increase in
test requests and increased number of worried-well in clinics led to a change. Also, the
number of people with mild disease who might not otherwise seek care confuses the
situation. Later recommendations focused on those who were hospitalized or at high risk,
so the surveillance results change. Furthermore, recommendations varied by jurisdiction,
and there was uncertainty about the performance of rapid tests and direct fluorescent
antibody (DFA) testing.
Dr. Jernigan said rapid tests are popular with doctors and they have a place, because
positive results mean something. Recent data show rapid tests for seasonal influenza
have an average sensitivity of 27% (ranging from 19% to 32%) and average specificity of
97% (range: 96–99%). A DoD Global Emerging Infections Surveillance and Response
System (GEIS) site used nasal wash specimens from clinics and compared rapid lab tests
with PCR; it found sensitivities ranging from 12% for novel H1N1 to 40% for influenza
A, but 99% specificity for novel H1N1, influenza A, and influenza B. Dr. Jernigan said
PCR seems to be emerging as the de facto standard.
Dr. Jernigan reiterated the CDC’s projections for the course of the disease. PCR kits
continue to be distributed globally, which is expensive. The so-called swine primers
have been submitted for FDA approval so they can become part of the assay. The PCR
protocol has been published, which will allow people to make their own assays.
Dr. Jernigan outlined some of the successes of the planning and response, including the
insistence on focusing more broadly than H5N1 for diagnostic tests and the investment in
public health labs’ diagnostic and development capacity (although more is still needed).
The challenges include the following:
Pandemic H1N1 subtyping capability is largely limited to public health
laboratories.
Many laboratories are unable to handle a surge.
PCR reagents were in short supply early in the outbreak.
Clinicians do not have accessible tests for diagnosing pandemic H1N1.
Increased number of laboratory-developed tests and new technologies may assist
diagnosis, but are difficult to validate.
Rapid antigen detection tests remain with some uncertainty in performance.
Engagement of CDC with diagnostic companies for accelerated assay
development could be improved.
Upcoming season may have H1, pandemic H1, H3, and B at once, making for a
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