The document summarizes the results of the 7th round of COVID-19 sentinel surveillance conducted in West Bengal from October 27-29, 2021. Key findings include: - Positivity rates varied between districts and over time, ranging from 0-4.72% across districts. - Vaccine efficacy for those receiving one dose was estimated at 78% based on the 6th round and 74% based on the 7th round. - Vaccine efficacy for those receiving two doses was estimated at 81% for the 5th round and 84% for the 6th round. - The 8th round of sentinel surveillance will be conducted from November 15-17 to continue monitoring trends and informing control strategies.

1. COVID 19 SENTINEL SURVEILLANCE,
WEST BENGAL (SEVENTH ROUND)
27th – 29th October, 2021

2. Introduction
Sentinel Surveillance for COVID-19 helps in complementing the outbreak
surveillance and investigations.
Sentinel surveillance is an efficient way to collect high-quality data in a timely
manner systematically and routinely from representatives of the population
under surveillance.
Sentinel surveillance for COVID-19 is a cost effect way to meet some of the
following objectives: -
monitor the geographic spread
intensity of transmission
severity trends of community transmission of COVID-19 over time

3. SENTINEL SURVEILLANCE BY DISTRICTS 5th , 6th &7th ROUND - A COMPARISON
Tested Positive
Positivity
Rate 95% CI Tested Positive
Positivity
Rate 95% CI Tested Positive
Positivity
Rate 95% CI
1 CBR MJM CBR 400 410 5 1.22 0.2-2.3 409 3 0.73 -0.1-1.6 412 6 1.46 0.3-2.6
2 APD APD DH APD 400 400 2 0.50 -0.2-1.2 401 4 1.00 0-2.0 400 0 0.00 0
3 KPG KPG DH NBMC 400 435 4 0.92 0.0-1.8 438 17 3.88 2.1-5.7 319 0 0.00 0
4 DAR Siliguri DH NBMC 400 419 8 1.91 0.6-3.2 403 15 3.72 1.9-5.6 409 11 2.69 1.1-4.3
5 JAL JAL DH NBMC 400 429 6 1.40 0.3-2.5 429 6 1.40 0.3-2.5 405 2 0.49 -0.2-1.2
6 UD Raiganj MCRaiganj MC 400 400 0 0.00 0 400 0 0.00 0 300 2 0.67 -0.3-1.6
7 DD Balurghat DH
Malda MC 400 400 12 3.00 1.3-4.7 400 9 2.25 0.8-3.7 400 7 1.75 0.5-3.0
8 Malda Malda MC Malda MC 400 400 4 1.00 0.0-0.2 400 1 0.25 -0.2-0.7 400 3 0.75 -0.1-1.6
9 MSD MSD MCH MSD MC 400 418 0 0.00 0 406 0 0.00 0 404 0 0.00 0
10 Rampurhat HD
Rampurhat MC
Rampurhat MC 400 591 0 0.00 0 408 0 0.00 0 435 6 1.38 0.3-2.5
11 Birbhum Suri DH Suri DH 400 413 0 0.00 0 408 0 0.00 0 409 7 1.71 0.5-3.0
12 Nadia Krishnanagar DH
JNM Kalyani 400 440 4 0.91 0.0-1.8 427 2 0.47 -0.2-1.1 409 3 0.73 -0.1-1.6
13 Basirhat HD
Basirhat SDH
CNMC 400 421 13 3.09 1.4-4.7 434 3 0.69 -0.1-1.5 448 1 0.22 -0.2-0.7
14 N 24 Pgs Barasat DHNRSMC 400 400 12 3.00 1.3-4.7 419 4 0.95 0-1.9 415 2 0.48 -0.2-1.1
15 S 24 Pgs Baruipur SDH
IPGMER 400 400 2 0.50 -0.2-1.2 400 1 0.25 -0.2-0.7 400 11 2.75 1.1-4.4
16 DHHD DHMC DHMC 400 428 7 1.64 0.4-2.8 417 4 0.96 0-1.9 529 5 0.95 0.1-1.8
17 Kolkata RGKMC RGKMC 400 450 2 0.44 -0.2-1.1 450 1 0.22 -0.2-0.7 450 8 1.78 0.6-3.0
18 Purba Mid Tamluk DHTamluk Lab 400 408 17 4.17 2.2-6.1 405 6 1.48 0.3-2.7 404 5 1.24 0.2-2.3
19 NandigramNandigram DH
Tamluk Lab 400 220 3 1.36 -0.2-2.9 191 0 0.00 0 399 1 0.25 -0.2-0.7
20 Jhargram Jhargram DH
MMCH 400 468 7 1.50 0.4-2.6 517 2 0.39 -0.1-0.9 407 0 0.00 0
21 Pas Mid MMCH MMCH 400 381 4 1.05 0.0-2.1 414 7 1.69 0.4-2.9 397 3 0.76 -0.1-1.6
22 Bankura BSMC BSMC 400 411 7 1.70 0.5-3.0 402 4 1.00 0-2.0 394 5 1.27 0.2-2.4
23 Bisnupur HD
Bisnupur SDH
BSMC 400 425 13 3.06 1.4-4.7 402 17 4.23 2.3-6.2 402 9 2.24 0.8-3.7
24 Purulia Purulia MCPurulia MC 400 428 1 0.23 -0.2-0.7 421 1 0.24 -0.2-0.7 413 1 0.24 -0.2-0.7
25 Pas Burd Asansol DHAsansol Lab 400 407 7 1.72 0.5-3.0 404 4 0.99 0-2.0 407 9 2.21 0.8-3.6
26 Pur Burd BMCH BMCLab 400 400 2 0.50 -0.2-1.2 400 7 1.75 0.5-3.0 400 3 0.75 -0.1-1.6
27 Hooghly Hooghly DH
Immambera Lab 400 587 8 1.36 0.4-2.3 555 24 4.32 2.6-6.0 615 29 4.72 3.0-6.4
28 Howrah Howrah DH
STM, Kolkata 400 458 2 0.44 -0.2-1.0 410 0 0.00 0 405 3 0.74 -0.1-1.6
11200 11847 152 1.28 1.1-1.5 11570 142 1.23 1.0-1.4 11587 142 1.23 1.0-1.4
7th Round 27th Oct - 29th Oct 2021
TOTAL
Planned
5th Round 14-16 Sept 2021 6th Round 29 Sept - 1st Oct 2021
Sl no District Hospital
Testing
Lab

4. 7th ROUND SENTINEL
Surveillance 27th – 29th
OCT
Positivity Rate : 0.0 to 1.0
16 DISTRICTS
Comparison between 5th , 6th and 7th Round of Sentinel Surveillance (1)
6th ROUND SENTINEL
Surveillance 29 Sept-1st
Oct
Positivity Rate : 0.0 to 1.0
17 DISTRICTS
5th ROUND SENTINEL
Surveillance 14-16 SEPT
Positivity Rate : 0.0 to 1.0
12 DISTRICTS

5. Comparison between 5th , 6th and 7th Round of Sentinel Surveillance (2)
6th ROUND SENTINEL
Surveillance 29 Sept-1st
Oct
Positivity Rate : 1.0 to 2.99
7 DISTRICTS
• Jalpaiguri
• Dakhin Dinajpur
• Purba Midnapore
• Paschim Midnapore
• Purba Burdwan
• Alipurduar
• Bankura
7th ROUND SENTINEL
Surveillance 27th – 29th
OCT
Positivity Rate : 1.0 to 2.99
11 DISTRICTS
• Purba Midnapur
• Bankura
• Rampurhat
• Kochbehar
• Birbhum
• Dakhin Dinajpur
• Kolkata
• Paschim Burdwan
• Bishnupur
• Darjeeling
• S24 Pgs
5th ROUND SENTINEL
SURVEILLANCE 14-16
SEPT
Positivity Rate : 1.0 to 2.99
11 DISTRICTS
• Kochbehar
• Jalpaiguri
• Darjeeling
• Malda
• Diamond Harbour
• Nandigram
• Jhargram
• Paschim Midnapur
• Bankura
• Paschim Burdwan
• Hooghly

6. 6th ROUND SENTINEL
Surveillance 29 Sept-1st
Oct
Positivity Rate : 3.0 to above
4 DISTRICTS
• Darjeeling (3.7)
• Kalimpong (3.8)
• Bisnupur HD (4.2)
• Hooghly(4.3)
Comparison between 5th , 6th and 7th Round of Sentinel Surveillance (3)
7th ROUND SENTINEL
Surveillance 27th – 29th
OCT
Positivity Rate : 3.0 to above
1 DISTRICT
• Hooghly(4.72)
5th ROUND SENTINEL
SURVEILLANCE 14-16
SEPT Positivity Rate : 3.0 to
above
5 DISTRICTS
• Dakhin Dinajpur (3.0)
• N24 Pgs (3.0)
• Bishnupur HD (3.1)
• Basirhat HD (3.1)
• Purba Midnapur (4.2)

7. MORBIDITY PROFILE OF THE PARTICIPANTS ≥ 45 YEARS OF AGE
130
78
148
26
28
6
1
0
20
40
60
80
100
120
140
160
HYPERTENSION
DIABETES
CHRONIC LUNG DISEASE
OBESITY
CHRONIC RENAL DISEASE
HEART DISEASE
MALIGNANCY

8. 6th and 7th Round Sentinel Surveillance
Calculation of Vaccine Efficacy
Vaccinated – Getting one dose of Covaxin or Covishield 28 days before
Among 18 years group and above (6th Round)
Vaccination
Status
mentioned
Non
Vaccinated
Vaccinated
No Covid-19 5372 2264
Covid-19 99 10
Total 5471 2274
Incidence among non vaccinated = 1.81
Incidence among Vaccinated = 0.4
Vaccine Efficacy = (1.81-0.4) / 1.81 = 0.78
i.e. 78 %
Vaccination
Status
mentioned
Non
Vaccinated
Vaccinated
No Covid-19 6443 2232
Covid-19 90 8
Total 6533 2240
Among 18 years group and above (7th Round)
Incidence among non vaccinated = 1.38
Incidence among Vaccinated = 0.36
Vaccine Efficacy = (1.38-0.36) / 1.38 = 0.74
i.e. 74 %

9. Vaccination
Status
mentioned
Non
Vaccinated
Vaccinated
No Covid-19 6744 892
Covid-19 106 3
Total 6850 895
5th and 6th Round Sentinel Surveillance
Calculation of Vaccine Efficacy
Vaccinated – Getting two doses of Covaxin or Covishield 28 days before
Incidence among non vaccinated = 1.55
Incidence among Vaccinated = 0.3
Vaccine Efficacy = (1.55-0.3) / 1.55 = 0.81
i.e. 81 %
Vaccination
Status
mentioned
Non
Vaccinated
Vaccinated
No Covid-19 7747 928
Covid-19 96 2
Total 7843 930
Incidence among non vaccinated = 1.22
Incidence among Vaccinated = 0.2
Vaccine Efficacy = (1.22-0.2) / 1.22 = 0.84
i.e. 84 %
6th Round 7th Round

10. CONCLUSION
• Sentinel Surveillance conducted in all the districts and in each round
samples are collected as per target
• Positivity rates are varied by districts and over period of time.
• Vaccine efficacy is high indicating the effectiveness of the vaccination
program which will be number one priority in all eligible age group
• Sentinel Surveillance to continue
• The eighth round for the Sentinel surveillance for planning strategies for
control of COVID19 human infection in West Bengal to begin from
• 15th November 2021 to 17th November 2021 - Completion of sample collection
• 18th November 2021 to 19th November2021 - All reports from Lab with excel sheet must be
mailed to the Nodal person, at State level at the email ids mentioned:
covid 19.1ab.spsrc@gmail.com
lizaprasu@gmail.com