“CAUTION IS THE KEY”
A study of the passengers on the Diamond Princess Cruise ship estimated
the proportion of asymptomatic persons as 17.9% (95%CrI: 15.5−20.2%)
among all infected cases. Therefore, the actual number of infected
individuals may be much higher than accounted for based on symtoms
only.1 Out of 81 women testing positive for Covid in
May 2020, 30.8% (25/81) belonged to the green zone. These asymptomatic
or pauci-symptomatic cases would be potential source of infection.
These women were being tested by RT-PCR (Reverse Transcription
Polymerase Chain Reaction test) considered to be the gold standard for
identification of SARS-CoV-2 virus. These swabs needed to be sent to lab
while maintaining cold-chain (temperature- 2-4oC).
Limitations included storage of testing kit and samples under stringent
low temperature conditions. The test also relies on the analysist’s
capabilities while testing and interpretation of results. At a time when
all suspected patients were being subjected to RT-PCR and the facility
was overloaded with the sample size, subjecting asymptomatic patients
too to RT-PCR was not feasible. Our tertiary care hospital was
struggling to accommodate high sample load from all over the city.
Hence, the results of RT-PCR were coming by 48 hrs. So, the need for a
rapid diagnostic test was felt.
As ICMR approved molecular diagnostic tests ( Truenat test) for testing
low-risk individuals, we immediately deployed this test to test our
green zone women as a universal screening method.3Truenat-beta is a chip-based RT-PCR test, kit stable at room temperature
and offering quick results. It effectively enabled early testing,
reporting within 2 hours of receiving the sample and earlier patient
isolation initiation (if required).
After utilising Truenat test, we detected 27 Covid positives (38.5% of
total 70 Covid positive women) from holding area and hence prevented
them from mixing with Green zone women. These Truenat positive women
were isolated in orange zone and tested for confirmatory RT-PCR test as
recommended by ICMR .
Out of these 27 Truenat positive women, 22 could be tested for RT-PCR.
Rest 5 could not be tested due to various reasons ( 1 patient expired,
one destitute patient could not be traced and 3 were sent for home
isolation as hospital laboratory was not working). 19 of these 22 ( 86.3
%) were confirmed positive and sent to Red zone. 3 had negative RT-PCR.
They were asymtopmatic and no history of contact with symptomatic
persons. We concluded that the initial sample might have been
contaminated.
Telephonic follow-up was done for these women and out of the 22 Truenat
positives, 63.6% (n=14) stayed asymptomatic and 36.3% (n=8) were
symptomatic anytime within 14 days after sampling.
79 % Truenat results (106 out of 135) were dispatched on the same day.
This policy had an added advantage of reducing the burden on
microbiology laboratory as well as reduced hospital stay as the results
came in early. Also, this helped in early segregation of positive
patients.