Seroprevalence of anti-SARS-CoV-2 antibodies in residents of Karachi—challenges in acquiring herd immunity for COVID 19

Abstract

Background The recent pandemic by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a global emergency. There is large number of asymptomatic cases of SARS-CoV-2 that are not reported. Hence, serological evidence of SARS-CoV2 antibodies is warranted for a better estimation of the actual number of infected patients to limit the disease spread and to get an idea of herd immunity. Methods This is a cross-sectional study conducted from May 2020 to July 2020 at National Institute of Blood Diseases at Pakistan. The study includes healthcare workers (HCWs), community and industrial workers. The anti-SARS-CoV-2 test was performed by electrochemiluminescence immunoassay analyzer. Results A total of 1675 samples have been received from three groups of population. The percentage positivity for industrial employees is high (50.3%) for HCW (13.2%) and community population (34%).Total percentage for positive antibodies result is ~36%. Conclusion Our seroprevalence is 36%, which still far from herd immunity that needs to be at least 60–70% in population. If we consider acquiring 60% seroprevalence in next few months, then herd immunity is not far from reality, provided the antibodies did not decline with time. Although the current study is based on a small sample of participants, the findings suggest a study with larger population to implement stronger and targeted interventions.

Low uptake of COVID-19 prevention behaviours and high socioeconomic impact of lockdown measures in South Asia: Evidence from a large-scale multi-country surveillance programme

“…Our results are consistent with an assessment of flu-like symptoms amongst healthcare workers in India during the same period ( Jha et al, 2020 ), but contrast with the findings of serology studies in Delhi and other urban South Asian settings, which indicate a high proportion of the populations tested may have been infected with COVID-19 during the lockdown ( ero-prevalence st, 2020 ; (2020). TheR, 2020 ; Zaidi et al, 2020 ). These observations suggest that a high proportion of people in South Asia may be infected asymptomatically, in keeping with the younger age distribution of South Asian populations, compared to European or North American countries.…”

Tracking SARS-CoV-2 infection in India with serology

“…7 The age structure of the population and under-reporting of deaths are both proposed as possible reasons for the lower value, but other data from Asia also indicate high rates of asymptomatic infections. 8 Within the wider context of the pandemic are several local epidemics at different stages of progression. The higher seroprevalence in urban areas and areas with an influx of migrants indicate that high contact rates probably fuelled the rapid spread of the virus.…”

Categorizing the Status of COVID-19 Outbreaks Around the World

“…Several research studies have suggested that some L&MICs might have moderate to high levels of infection. Seroprevalence studies in Qatar [3] , Manaus (Brazil) [4] , Pakistan [5] , South Africa [6] and Nairobi (Kenya) [7] reported finding antibodies for SARS-CoV-2 in large percentages of the studied populations. Estimates of actual deaths due to COVID-19, combined with estimates of expected mortality rates, similarly suggest that SARS-CoV-2 has infected large shares of the populations in several L&MICs [8] , including Bolivia, Ecuador, Peru, Mexico and South Africa [9] , Sudan [10] , Syria [11] , Yemen [12] and Zambia [13] .…”