Assessing seropositivity for IgG antibodies against SARS-CoV-2 in Ahmedabad city of India: a cross-sectional study

Abstract

ObjectivesTo study the percentage seropositivity for SARS-CoV-2 to understand the pandemic status and predict the future situations in Ahmedabad.Study designCross-sectional study.SettingsField area of Ahmedabad Municipal Corporation.ParticipantsMore than 30 000 individuals irrespective of their age, sex, acute/past COVID-19 infection participated in the serosurvey which covered all the 75 Urban Primary Health Centres (UPHCs) across 48 wards and 7 zones of the city. Study also involved healthcare workers (HCWs) from COVID-19/non-COVID-19 hospitals.InterventionsSeropositivity of IgG antibodies against SARS-CoV-2 was measured as a mark of COVID-19 infection.Primary and secondary outcomesSeropositivity was used to calculate cumulative incidence. Correlation of seropositivity with available demographic detail was used for valid and precise assessment of the pandemic situation.ResultsFrom 30 054 samples, the results were available for 29 891 samples and the crude seropositivity is 17.61%. For all the various age groups, the seropositivity calculated between 15% and 20%. The difference in seropositivity for both the sex group is statistically not significant. The seropositivity is significantly lower (13.64%) for HCWs as compared with non-HCWs (18.71%). Seropositivity shows increasing trend with time. Zone with maximum initial cases has high positivity as compared with other zones. UPHCs with recent rise in cases are leading in seropositivity as compared with earlier and widely affected UPHCs.ConclusionsThe results of serosurveillance suggest that the population of Ahmedabad is still largely susceptible. People still need to follow preventive measures to protect themselves till an effective vaccine is available to the people at large. The data indicate the possibility of vanishing immunity over time and need further research to cross verify with scientific evidences.

Population-based seropositivity for IgG antibodies against SARS-CoV-2 in Ahmedabad city

“…Ahmedabad Municipal Corporation (AMC), from the state of Gujarat, India, had already completed one large scale population-based sero-surveillance for IgG antibodies against SARS-CoV-2 Virus with an average positivity of 17.61% at the end of June 2020. 7 During the one and half month after the initial survey, there are additional cases of COVID-19. So, a repeat population-based sero-survey was planned to study the COVID-19 seropositivity.…”

Seroprevalence of IgG antibodies against SARS-CoV-2 in India, March 2020 to August 2021: a systematic review and meta-analysis

“…V. Murhekar, et al, 2021;Naushin et al, 2021;Padma et al, 2021;Parai et al, 2021;Prakash et al, 2021a. ;Prakash et al, 2021b;Prakash et al, 2021c;Prakash et al, 2021d;Rafi et al, 2021;Ray et al, 2020;Satpati et al, 2020;Selvaraju et al, 2021;Sen et al, 2021;N. Sharma et al, 2020.;Siddiqui et al, 2020;Singhal et al, 2020;Siva Ganesa Karthikeyan et al, 2021;Velumani et al, 2021;Venkataraman et al, 2021) with 831,010 participants in the first wave (COVID-19sero survey-III (July 2021) -Tamil Nadu, 2021.; Misra et al, 2021;Selvaraju et al, personal communication;M.…”

SARS-CoV-2 seroprevalence in the city of Hyderabad, India in early 2021

“…We have documented much higher seroprevalence in Hyderabad (54.2%) than that seen in other states such as Tamil Nadu (31%) [15], Uttar Pradesh, Gujarat, West Bengal, Madhya Pradesh, Karnataka and Chhattisgarh (41%) [16] in the same time frame (November 2020 to January 2021). A few other studies have reported much lower seroprevalence of 17.6% in Ahmedabad [17] and 3.1% in Srinagar [18] in November-December 2020. The findings of our study are similar to those from Mumbai [5], Chennai [6] and in Karnataka [7] conducted during the months of July 2020, suggesting that urban populations have had much higher seroprevalence than the national average prevalent at that time.…”