ICMR EPIDEMIOLOGICAL STUDY

ICMR has published a good epidemiological summary paper of COVID-19 cases from Jan22-April30 in India

I encourage you to read it at

ijmr.org.in/temp/IndianJMe…

Here are key insights for me from this paper

Only 60% of COVID-19 cases have Fever at point of testing(thermal screening less likely to work in 40%). 31% have breathlessness (they present late in Moderate COVID stage). Many have atypical Symptoms .

Hence Testing Criteria should be expanded to include these symptoms and (not restricted to checking for Influenza like Illness only in hot zones) to detect early.

6.1+2.6=8.7% cases are ILI in hot zones+SARI implying no known contacts.So a small but significant evidence of Community Transmission.

Direct contacts(Symptomatic: ASymptomatic =25.3:10.6 i~2.3,hence a majority of contacts are asymptomatic at point of testing)

Thus standard Symptom/Screen is going to fail to trace these. Hence we need PPE in community (Mask/Shield/Sanitizer)

5.2%(2082). cases are healthcare workers .

From world literature Positivity Rate of Direct contact is around 1% and Household~10%.

In India it is reported as 5.1% . Thus a significant number of direct contact members are in household.

Health care worker positivity rate (2.3-4.6% is lower than that in contacts(5.1-10.3%) implying significant risk among Household n crowded areas.

These imply significant transmission in closed/crowded area with prolonged contacts.

The secondary attack rates also is suggestive of droplet transmission being major mode as airborne mode(measles, chicken pox) leads to 30-50% household Infection rate.

In States with cases>1000 ,secondary attack rates to direct contacts are higher in Gujarat,Delhi, Maharashtra. These states also have higher Total positivity rates. Thus populations density is also playing a large role in transmission.

Infection rate is higher in above 50 age group and males possibly due to Age dependent ACE 2 Receptor expression which makes SARS-COV2 Infection more likely. 2x Males than Females.

Rate of getting Infection in 60+ population is 1.5 times higher (9.9+3.8+1.1(case% above 60) /9.9(population% above 60)).

Mortality rate is about 10 times higher in 60+ age group(1.5% Vs 15%).

Would like to correct this tweet. (Can’t do without breaking the thread)

SARI(10.5)+ILI(3)=13.5% .

So around 1 in 7 Patients have unknown contacts suggesting Community Transmission. Will be useful to look it state/districtwise

6.1+2.6=8.7% cases are ILI in hot zones+SARI implying no known contacts.So a small but significant evidence of Community Transmission.

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