H1N1 COUNTERMEASURES STRATEGY AND ... - PHE Home

NBSB Pandemic Influenza Working Group
Detailed Report
provides virus to developers and researchers, PCR reagents for assays, WHO reference
kits, proficiency testing, surge capacity, and an online storefront for access to reagents.
CDC anticipated there would be lots of test requests early, and better preparation was
needed. Diagnostic testing needs differ before a pandemic, at the outset, and during the
pandemic. Before a pandemic, the prevalence of disease is low, PPV of testing is low,
and diagnostics have high sensitivity and specificity. The crisis level is low but vigilance
is critical. The negative implications of false-positive tests are a factor.
As the virus is identified, the prevalence early on is still likely to be low and the virus
may occur with seasonal influenza. The PPV of testing is still low and the test should
distinguish seasonal from novel influenza. Early detection is critical and the crisis level
is high. During a pandemic, prevalence is high, PPV is high (as determined by clinical
and lab diagnosis), and the focus of testing is on clinical diagnosis and management.
Broad surveillance is still needed.
Diagnostic development efforts can be categorized by short-, medium-, and long-term
needs. In the short term, we need diagnostics that improve our capacity to detect an
unusual virus. Public labs need sensitive, specific assays. We need to improve subtyping
of known influenza strains and the flexibility to detect unsubtypable strains. In the
medium term, POC tests for clinics and emergency departments (ED)s, and lab tests for
hospitals are needed.
In the long term, we need an improved simple influenza test for CLIA-waived or nonmedical
settings, a more automated approach to testing, tests to detect antiviral resistance,
and rapid antibody tests. Dr. Jernigan said development of diagnostic tests is not as far
along as CDC would like.
CDC and FDA partnered with Applied Biosystems for a relatively cheap, fast trial that
set the platform for rapid validation of sequences for new assays. The five-target assay
has high sensitivity and high specificity. In April, 37 labs were qualified to use the
diagnostic device, and now 95 labs are qualified. CDC plans to continue rolling out the
device to support surge capacity.
The Mesoscale diagnostic POC test detects antigen by means of a nasal swab that goes
into a cartridge that is inserted into a machine. It was being tested at a Naval Health
Research Center (NHRC) in San Diego and picked up an unsubtypable strain. It works in
about 15 minutes and allows the user to identify influenza A that has not been seen
previously. Dr. Jernigan described the use of the Mesoscale device to detect the first case
of the pandemic and subsequent confirmation by a Wisconsin State public health lab.
The case was reported to WHO. Surveillance was enhanced in Southern California and
then expanded nationally when H1N1 was identified in Mexico.
Detection was also enhanced by use of the PCR testing kits that were manufactured under
an EUA and shipped within 2.5 weeks of identifying the virus. They were distributed to
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