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Volume 27, Number 2—February 2021
Research Letter

Prevalence and Time Trend of SARS-CoV-2 Infection in Puducherry, India, August–October 2020

Sitanshu Sekhar KarComments to Author , Sonali Sarkar, Sharan Murali, Rahul Dhodapkar, Noyal Mariya Joseph, and Rakesh Aggarwal
Author affiliation: Jawaharlal Institute of Postgraduate Medical Education and Research, Puducherry, India

Main Article

Table

Seroprevalence of SARS-CoV-2 antibodies in 3 surveys in Puducherry, India, 2020*

Variable August 11–16, n = 869
September 10–16, n = 898
October 12–16, n = 900
No, positive/ no. tested % (95% CI) No. positive/ no. tested % (95% CI) No. positive/ no. tested % (95% CI)
Crude prevalence
43/869
4.9 (3.5–6.4)

186/898
20.7 (18.0–23.3)

311/900
34.5 (31.5–37.7)
Age category, y
18–29 8/170 4.7 (1.5–7.8) 33/165 20.0 (13.9–26.1) 58/180 32.2 (25.8–39.3)
30–44 13/295 4.4 (2.1–6.7) 58/277 20.9 (16.2–25.7) 92/252 36.5 (30.8–42.6)
45–59 13/242 5.4 (2.5–8.2) 64/271 23.6 (18.5–28.7) 101/259 39.0 (33.2–45.0)
>60
9/162
5.6 (2.0–9.1)

31/185
16.7 (11.4–22.1)

60/209
28.7 (23.0–35.1)
Sex
M 16/439 3.6 (1.9–5.4) 95/443 21.4 (17.6–25.2) 126/406 31.0 (26.7–35.6)
F
27/428
6.3 (4.0–8.6)

91/455
20.0 (16.3–23.6)

183/491
37.2 (33.1–41.6)
Residence setting†
Urban 35/609 5.7 (3.9–7.5) 130/629 20.7 (17.5–23.8) 225/628 35.8 (32.1–39.7)
Rural
8/260
3.1 (1.0–5.2)

56/269
20.8 (16.0–25.7)

86/272
31.6 (26.3–37.4)
Occupation‡
Healthcare workers 2/29 6.9 (1.0–22.8) 4/32 12.5 (1.0–24.0) 18/66 27.2 (18.0–39.0)
Other frontline workers 0/22 0 8/23 34.8 (15.3–54.2) 6/15 40.0 (19.0–64.2)
Others
41/818
5.0 (3.5–6.5)

174/843
20.6 (17.9–23.4)

287/819
35.0 (31.8–38.3)
Other characteristics
COVID-19 4/34 11.8 (9.3–22.6) 16/47 34.0 (20.5–47.6) 82/184 44.5 (37.5–51.7)
COVID-19 diagnosis 3/3 100 3/7 42.9 (6.1–79.5) 25/29 86.2 (69.4–94.5)
COVID-19 symptoms in last 6 mo
8/85
9.4 (3.2–15.6)

10/44
22.7 (10.3–35.1)

85/148
57.4 (49.3–65.1)
Cumulative case incidence (cumulative incidence ratio)§
2,987 (0.25%)

12,331 (1.03%)

23,080 (1.92%)
Infection-to-case ratio¶
4.9%/0.25% = 19.6

20.9%/1.03% = 20.0

34.5%/1.92% = 18.0
Cumulative deaths
43

187

441
Infection fatality ratio (cumulative deaths per 100,000 infected persons)# 73.4
75.8
106.1

*COVID-19, coronavirus disease; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2.
†Definitions used by the Office of the Registrar General & Census Commissioner, Government of India.
‡Other frontline workers included police officers, teachers, revenue officers, persons involved in COVID-19 response.
§Calculated for data gathered until 2 weeks before the midpoint of the survey.
¶Infection-to-case ratio was calculated as crude seroprevalence / cumulative incidence ratio.
#Infection-fatality ratio was calculated as cumulative deaths/crude prevalence × estimated population of the district.

Main Article

Page created: December 10, 2020
Page updated: January 24, 2021
Page reviewed: January 24, 2021
The conclusions, findings, and opinions expressed by authors contributing to this journal do not necessarily reflect the official position of the U.S. Department of Health and Human Services, the Public Health Service, the Centers for Disease Control and Prevention, or the authors' affiliated institutions. Use of trade names is for identification only and does not imply endorsement by any of the groups named above.
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