Dr K K Aggarwal
President CMAAO
With inputs from
Dr Monica Vasudev
936: Round Table
Expert Zoom Meeting on “Formulas in relation to COVID-19 pandemic for better
understanding of data”
30th
May, 2020; 11am-12pm
Participants: Dr KK
Aggarwal; Dr Alex Thomas; Dr AK Agarwal; Dr DR Rai; Dr Suneela Garg; Dr Girdhar
Gyani; Dr Ashok Gupta; Dr Jayakrishnan Alapet; Mr Bejon Misra; Dr K Kalra; Mrs
Upasana Arora; Dr Major Prachi Garg; Ms Ira Gupta; Dr Sanchita Sharma
- It has been seen
that 1% of symptomatic cases die.
- Expected
number of symptomatic cases: Number of deaths x 100 will
give the expected number of symptomatic cases in society on that day. For
instance, if the number of deaths is 400. So, by this definition, the app.
number of cases should be 40,000.
- Corrected
death rate: Currently, the death rate is calculated
as number of cases today vis a vis number of deaths today. Instead, it
should be number of cases today vs number of cases 14 days back. The
corrected death rate is 5.76%.
- Doubling
time: The doubling time in India is 14 days, Russia 20
days, Brazil 13 days, whereas the doubling time is longer in other
countries (USA 36 days, UK 37 days, Spain 40 days, Italy 57 days, France
52, Germany 55 days). If social distancing is not maintained, numbers in
India are going to be very high. India will be in top 6 in one week.
- China conducted
6.5 million tests for coronavirus, where 6 new cases were detected two
weeks ago; 200 cases were found, mostly people who showed no symptoms. The
ratio of undocumented cases for each documented case in Wuhan is 1:33 i.e.
there were 33 asymptomatic cases for every one new infection. This is a
reliable study as the total population was tested and not a sample
population.
- In a study from
New York City, this ratio is 1:10 i.e., there were 10 asymptomatic patients,
for every positive patient. New York conducted an antibody testing study,
while Wuhan did antigen test. The reliability of antibody test is unknown.
There are smaller studies from Iceland (1:2), Germany (1:5), California
(1:5).
- According to
CDC, the mortality is less than 0.3% as we are missing asymptomatic cases.
- As RTPCR is 67% specific add 30% in government
figures of number of cases; more the number, less will be the
mortality.
- People who are
brought in dead are declared as COVID negative; COVID is not reported as
the primary cause of death; therefore, these cases may not be counted.
- To get the
actual number of deaths, multiply the government figures by 2.
- Deaths
per million population: US 316, Spain 580, World 47.1, India
4. While this number for India may seem very good, we must not compare
country to country. We must compare epicenter to epicenter. Mortality in
China is very high, if only Wuhan is taken, but if you add rest of China,
the mortality becomes very low.
- Herd
immunity threshold (HIT): It is calculated as R0-1 divided
by R0 (R0 or R naught is reproduction number).
o
If R0 is 3, then 66% of population would need
to get infected to develop herd immunity
o
If R0 is 2, then 50% of population would need
to get infected to develop herd immunity.
o
If R0 is 1.5, then 33% of population would
need to get infected to develop herd immunity.
o
If R0 is 1.4, then 28.5% of population would
need to get infected to develop herd immunity.
o
If R0 is 3.5, then 71.5% of population would
need to get infected to develop herd immunity.
In New York,
infection stopped when 23% of the population had the infection. Their R value
was 1.3. The HIT was 23%.
So, the day we cross
20% of cases, we will see regression of infection with no new cases in the
community. First to do this will be Delhi or Maharashtra, next will be Tamil
Nadu and West Bengal.
Scenarios
- If no measures
are taken (such as lockdown, social distancing, or any other), the disease
continues to spread; R0 is 2.66.
- In moderate
lockdown, transmission is reduced (R0) to 2 during the lockdown,
transmission resumes at R0 of 2.4 after the lockdown; a surge in
post-lockdown period is expected.
- Hard lockdown:
R0 is reduced o 1.5 during lockdown, then transmission resumes at R0 of
2.4.
- Hard lockdown +
continue social distancing/isolating symptomatic cases: R0 is reduced o
1.5 during lockdown, then we can continue at R0 of 2 through social
distancing and isolation.
- Families rather
than individuals are now being affected. During lockdown, the message that
went out was to stay at home and wear a mask when going out. This message
needs to be changed. People who go out and come back to their house should
continue to wear a mask; else one person will infect the entire family.
Social distancing at home is as important as social distancing in office
or outside at other places.
- Every death
should be audited to find out if these deaths could have been prevented.
- The virus has
different presentations in different patients.
o
It is a viral disorder and is self-limiting
in 90% patients. Antivirals should be given within 48 hours.
o
The virus behaves like HIV in some patients;
if lymphopenia or reduced CD4 cell count, give anti-HIV drugs
o
It produces hyperimmune inflammation, so if
there are signs of hyperinflammation such as high ESR, CRP and ferritin,
anti-inflammatory drugs such as HCQ, indomethacin become important.
o
It behaves like bacteria, so azithromycin can
be given; azithromycin may cause cardiotoxicity, so doxycycline may be given,
which also covers atypical bacteria.
o
It produces thrombo-inflammation; fibrinogen
and d-dimer levels are raised; such patients have moderate/ severe illness.
Give anticoagulant – heparin, nafamostat
o
It produces silent hypoxia; oxygen
supplementation with high flow nasal cannula, BiPAP (if required) and
ventilator (only 1%).
o
Cytokine storm and ARDS: this is terminal
illness and managed as per protocol for ARDS.
- The fear and
stigma around a dead body (Covid) needs to be removed. Once a body is
cleaned as per protocol and wrapped, it is not infected. There is no risk of
spread of infection and so no need for PPE for cremations.
- The minimum
space requirement for working in office, according to WHO, is 100 sq ft
per person. In India, the standard is 75 sq ft per person for living.
- A patient who
came to the clinic in the morning and tests positive in the evening,
answer the following question:
o
Was the patient wearing a mask? If yes, then
ask,
o
Was the doctor wearing a mask? If yes, then
ask,
o
Was the surface decontaminated in the
morning? If yes, then ask,
o
What was the contact time? If less than 30
min: Monitor; If more than 30min: Quarantine
- Best protection
guidelines for doctors as well as patients should be displayed in each
clinic.
