COVID-19 infection, and reinfection, and vaccine effectiveness against symptomatic infection among health care workers in the setting of omicron variant transmission in New Delhi, India.
Lancet Reg Health Southeast Asia
; 3: 100023, 2022 Aug.
Article
in English
| MEDLINE | ID: covidwho-1945945
ABSTRACT
Background:
Surge of SARS CoV-2 infections ascribed to omicron variant began in December 2021 in New Delhi. We determined the infection and reinfection density in a cohort of health care workers (HCWs) along with vaccine effectiveness (VE) against symptomatic infection within omicron transmission period (considered from December 01, 2021 to February 25, 2022.Methods:
This is an observational study from the All India Institute of Medical Sciences, New Delhi. Data were collected telephonically. Person-time at risk was counted from November 30, 2021 till date of infection/ reinfection, or date of interview. Comparison of clinical features and severity was done with previous pandemic periods. VE was estimated using test-negative case-control design [matched pairs (for age and sex)]. Vaccination status was compared and adjusted odds ratios (OR) were computed by conditional logistic regression. VE was estimated as (1-adjusted OR)X100-.Findings:
11474 HCWs participated in this study. The mean age was 36â 2 (±10â 7) years. Complete vaccination with two doses were reported by 9522 (83%) HCWs [8394 (88%) Covaxin and 1072 Covishield (11%)]. The incidence density of all infections and reinfection during the omicron transmission period was 34â 8 [95% Confidence Interval (CI) 33â 5-36â 2] and 45â 6 [95% CI 42â 9-48â 5] per 10000 person days respectively. The infection was milder as compared to previous periods. VE was 52â 5% (95% CI 3â 9-76â 5, p = 0â 036) for those who were tested within 14-60 days of receiving second dose and beyond this period (61-180 days), modest effect was observed.Interpretation:
Almost one-fifth of HCWs were infected with SARS CoV-2 during omicron transmission period, with predominant mild spectrum of COVID-19 disease. Waning effects of vaccine protection were noted with increase in time intervals since vaccination.Funding:
None.
Full text:
Available
Collection:
International databases
Database:
MEDLINE
Type of study:
Cohort study
/
Experimental Studies
/
Observational study
/
Prognostic study
Topics:
Vaccines
/
Variants
Language:
English
Journal:
Lancet Reg Health Southeast Asia
Year:
2022
Document Type:
Article
Affiliation country:
J.lansea.2022.100023
Similar
MEDLINE
...
LILACS
LIS