The lockdown is
on the way of it being lifted but the cases continue to rise in India. The Wuhan
virus does not seem anywhere near the peak at the moment. Yet there are signals
from different quarters about need to open up the economy. As the economy begins
to open up and the mobility is restored, the movement of people across the country
is resulting in the Wuhan flu getting spread to other parts of the country.
States like Karnataka, Orissa, Assam which had managed very well are now
fighting hard to contain the disease thanks to the migration from states like
Maharashtra, West Bengal among others. As the states and the centre begin the
mitigating strategies, it becomes pertinent to have a look at the data before
the appropriate strategic choices are made. Any decisions in the absence of
signals from data are bound to be self-limiting and on the contrary generate
numerous unintended consequences not necessarily pleasant.
It has been
nearly 100 days since the cases began flowing in. Of course, India’s first case
was in early February when three students returning from Wuhan tested positive
in Kerala. Given the nearly one hundred days of tracking, Indian Council of
Medical Research (ICMR) would have, in all probability, collected data on
different physiognomies of the disease. The symptoms seem well known but more
characteristics would be in order.
The importance
of data lies in identifying pre-symptomatic and asymptomatic. It is pertinent
to distinguish between the two. Current evidence indicates the low chance of
infectiousness among the asymptomatic but high degree of spread among the
pre-symptomatic. Further, incubation period has to be known. Evidence suggested
that symptoms emerging on an average in five days but could extend upto
fourteen days. That is how the fourteen day quarantine arose. If the symptoms
are unlikely to emerge after seven days, the quarantine period can be reframed.
The data now is available given the number of cases detected all over the
world. In March, when the world began to shut down, very little was known about
the characteristics of the Wuhan flu but in the last three months or so, sufficient
data should help us in identifying the trends in incubation period and the peak
periods of infectiousness.
If the virus
loses its infectiousness after a certain period, the whole dynamics of lockdown
will change. The data seems to suggest the median days of patient reporting
negative test is ten days from the day of positive test. It is observed that
more than 90% recover within three weeks. Residual traces of viruse might
remain in the body with the tests continuing to report positive but the virus
has lost its infectiousness. This was the foundation for the changed discharge
policy not only in India but many other countries.
Another critical
factor would be to identify the superspreader. Some spread the virus swift and
wide whereas others hardly spread to anyone. Epidemics have generally recorded
less than ten percent of the patients spreading the disease to around 70-80% of
the people. The real work lies in identifying these superspreaders. One method
is to undertake biological profile of these ‘Typhoid Mary’ s but that would be
tedious taking a lot of time and resources. It would be interesting to see if
there is a linkage between the viral
load and the spread of the disease.
The disease is
self-resolving in nearly 80% of the cases. The spreaders seem to follow the
Pareto law or the Gladwell law of the epidemics. If the super spreaders are identified, then
there is very little reason to fear others. Few precautions might well be in
order to contain the spread of the Chinese flu. One method of this
identification might be the viral load. If the viral load is high and contributes
to high infectiousness, then the test results itself point to possible measures
needed to be taken to arrest the disease. If low viral loads do not result in
higher spread, the positive patients being asked to stay at home and reduce the
contact could itself contain the disease. The problem here arises if the
patient has to meet a lot of people as part of his or her daily life. Reproduction
ratio might be low but the sheer number of people interacted might make large
number of people affected. This creates hurdles for mitigation. Therefore, the
viral load and its links with the reproduction ratio might be of crucial
importance in pandemic management.
Therefore, it is
desirable that ICMR makes these data available on the public domain. The data
needs to comprise of the incubation period, the number of asymptomatic
patients, the link between incubation period and infectiousness, the period of
infectiousness, the reproduction ratio, changing nature of reproduction ratio
with period of time, the recovery period, the viral loads in patients, the link
between viral load and disease spread, the viral load and severity of the
symptoms among others. More importantly, rather than the average recovery
period, it is the median recovery period and the second quartiles which might
be of more importance. Such data is also necessary for the incubation period. If
the second quartile of incubation period is less, then the policy planning might
be different in isolating the prospective patients than one wherein the first
quartile of the incubation period itself is high. Furthermore, the reproduction
ratio might not be constant and thus its characteristics over time need to be
plotted.
Yet, for all the
data that might have been recorded, ICMR has still not released the data.
Incidentally, it has to release the data from the sero-survey tests which it
has conducted in high risk areas. The test results from the use of hydroxychloroquinine
(HCQ) among frontline workers and the disease incidence would also be very
useful. At the moment, there is data scarcity from the ICMR, but hope that rich
data would be forthcoming that could shape up the future strategy in reopening
the economy.
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