As the transmission progressed, the lower seroprevalences at the end of wave 1 among the rural and urban affluent increased rapidly at the end of wave 2 to 67.6% and 85.4%, respectively, and probably reachedconsiderable population immunity. the rural and urban MPL slums. The majority of seropositive individuals (75%) were asymptomatic. Residence in urban slums (OR 2.02; 95% CI:1.57-2.6; p 0.001), middle socioeconomic status (OR 1.77; 95% CI:1.17-2.67; p=0.007), presence of diabetes (OR 1.721; 95% CI:1.148-2.581; p=0.009), and hypertension (OR 1.75; 95% CI:1.16-2.64; p=0.008) Paricalcitol were associated with seropositivity on multivariable analyses. Conclusion Although considerable population immunity has Paricalcitol been reached with more than two-thirds seropositivity, improved vaccination strategies among unreached subpopulations and high-risk individuals are suggested for better preparedness in future. chronic obstructive pulmonary disease A total of 588 participants (24.2%) reported symptoms suggestive of acute respiratory contamination or fever during the six months preceding sample collection. Symptoms were reported by 46.2% of healthcare workers,28.3% of the urban affluent group, 16.1% of the urban slum, and 13.4% of the rural group. Overall symptoms reported among participants were comparable during wave 1(27.6%)and wave 2(20.7%). Among the SARS-CoV-2 positive participants,30.7%and 22.5% were symptomaticduring wave Paricalcitol 1 and wave 2, respectively. Notably, only 4.1% of the study population had symptomatic infection requiring hospitalisation,most of which were for infection control purposes. In public places, cloth maskremained the most common type of mask used (58.1%)followed by surgical mask (35.1%), and N95(6.8%), respectively. Other human coronavirus antibodies (NL63, OC43) were detected in almost all the participants:99.6% of participants who were seronegative for SARS-CoV-2 and 100% of the participants who were seropositive for SARS-CoV-2 antibodies, respectively. The overall weighted prevalence of SARS-CoV-2 antibodies adjusted for the population of Paricalcitol Vellore was 28.5% (95% CI: 22.3%-33.7%) at the end of wave 1 and 71.6% (95% CI: 62.8%-80.5%) at the end of wave 2. At the end of wave 1, seroprevalence was found to be the maximum among individuals from urban slums (43.7%; 95% CI: 38.1%-49.4%) followed by healthcare workers (31.6%; 95% CI: 26.5% -37.0%), rural (26.8%; Paricalcitol 95% CI: 22.9%-32.2%), and urban affluent (24.7%; 95% CI: 20.0%-30.0%). At the end of wave 2, seropositivity was the maximum among healthcare workers (95.5%; 95% CI: 91.3%-98.0%) with a high vaccination rate of 91.6%(95% CI: 86.5%-95.2%). The urban affluent had similar high seropositivity of 85.4%(95% CI: 80.2%-89.6%) with 65.7%(95% CI: 59.3%-71.7%)of the participants being vaccinated. The urban slums and rural areas also had a high seroprevalence of 75.1%(95% CI: 70.2%-79.7%)and 67.8%(95% CI: 63.1%-71.9%), respectively, with only 6.6%(95% CI: 4.2%-9.8%) and 10.4%(95% CI: 7.7%-13.5%) of respective participants being vaccinated.The community seropositivity for IgG at the end of wave 1 and wave 2 for the four different subpopulations is tabulated in Table 2 and Figure 2 . The seroprevalence along with the vaccination status in different subpopulations at the end of wave 2 is depicted in Figure 3 . Seropositivity by different characteristics and time periods are depicted in Table 3. There was a slight shift in seropositivity noted from older age groups (above 60 and 40-60) in wave 1 to younger age groups (20-40 years and 1-20 years) in wave 2. This may be because of the larger proportion of the population who got infected during the second wave which is a reflection of the younger population in the country. Table 2 Community seroprevalence and vaccination status in different subpopulations thead th rowspan=”2″ align=”left” valign=”top” colspan=”1″ Subpopulation /th th colspan=”2″ align=”left” valign=”top” rowspan=”1″ End of Wave 1 (Jan 2021)(N=1,228) /th th colspan=”4″ align=”left” valign=”top” rowspan=”1″ End of Wave 2 (July 2021)(N=1,205) /th th valign=”top” rowspan=”1″ colspan=”1″ Serology IgG, n/N (%) or % /th th valign=”top” rowspan=”1″ colspan=”1″ 95% CI /th th valign=”top” rowspan=”1″ colspan=”1″ Serology IgG, n/N (%) or % /th th valign=”top” rowspan=”1″ colspan=”1″ 95% CI /th th valign=”top” rowspan=”1″ colspan=”1″ Vaccination status#, n/N (%) /th th valign=”top” rowspan=”1″ colspan=”1″ 95% CI /th /thead Rural81/302 (26.8)22.9 – 32.2307/454 (67.6)63.1 – 71.947/454 (10.4)7.7 – 13.5Urban Slum136/311 (43.7)38.1 – 49.4251/334 (75.1)70.2 – 79.722/334 (6.6)4.2 – 9.8Urban affluent73/295 (24.7)20.0 – 30.0204/239 (85.4)80.2 – 89.6157/239 (65.7)59.3 – 71.7Healthcare workers101/320 (31.6)26.5 – 37.0170/178 (95.5)91.3 – 98.0163/178 (91.6)86.5 – 95.2Overall weighted prevalence.