Seroprevalence of SARS-CoV-2 IgG antibody among healthy blood donors: a single centre study

Assessment of the COVID-19 pandemic progression in Ecuador through seroprevalence analysis of anti-SARS-CoV-2 IgG/IgM antibodies in blood donors

Introduction

Coronavirus Disease 2019 (COVID-19) is a severe respiratory illness caused by the RNA virus SARS-CoV-2. Globally, there have been over 759.4 million cases and 6.74 million deaths, while Ecuador has reported more than 1.06 million cases and 35.9 thousand deaths. To describe the COVID-19 pandemic impact and the vaccinations effectiveness in a low-income country like Ecuador, we aim to assess the seroprevalence of IgG and IgM antibodies against SARS-CoV-2 in a sample from healthy blood donors at the Cruz Roja Ecuatoriana.

Methods

The present seroprevalence study used a lateral flow immunoassay (LFIA) to detect anti-SARS-CoV-2 IgG and IgM antibodies in months with the highest confirmed case rates (May 2020; January, April 2021; January, February, June, July 2022) and months with the highest vaccination rates (May, June, July, August, December 2021) in Quito, Ecuador. The IgG and IgM seroprevalence were also assessed based on sex, age range, blood type and RhD antigen type. The sample size was 8,159, and sampling was performed based on the availability of each blood type.

Results

The results showed an overall IgG and IgM seroprevalence of 47.76% and 3.44%, respectively. There were no differences in IgG and IgM seroprevalences between blood groups and sex, whereas statistical differences were found based on months, age range groups, and RhD antigen type. For instance, the highest IgG seroprevalence was observed in February 2022 and within the 17-26 years age range group, while the highest IgM seroprevalence was in April 2021 and within the 47-56 years age range group. Lastly, only IgG seroprevalence was higher in RhD+ individuals while IgM seroprevalence was similar across RhD types.

Discussion

This project contributes to limited data on IgG and IgM antibodies against SARS-CoV-2 in Ecuador. It suggests that herd immunity may have been achieved in the last evaluated months, and highlights a potential link between the RhD antigen type and COVID-19 susceptibility. These findings have implications for public health strategies and vaccine distribution not only in Ecuador but also in regions with similar characteristics.

Seroprevalence of COVID-19 among voluntary blood donors

CONTEXT

COVID-19 usually presents with mild symptoms. No cases of transfusion - transmission of COVID-19 had been reported. Assessing the prevalence of viral infections among blood donors is essential to frame blood safety strategies.

AIM

The main aim of this study is to assess the seroprevalence of SARS-CoV-2 antibodies among healthy and asymptomatic voluntary blood donors by enzyme-linked immunosorbent assay (ELISA).

SETTING AND DESIGN

This cross-sectional study was conducted among voluntary blood donors using a consecutive sampling technique in the Department of Transfusion Medicine, the Tamil Nadu Dr. M.G.R. Medical University, Guindy, Chennai, for 18 months.

METHODS

Adhering to COVID-19 pandemic guidelines and donor eligibility criteria, blood samples collected from 500 asymptomatic unvaccinated voluntary blood donors were tested for SARS-CoV-2 (IgG + IgM + IgA and IgG) antibodies by ELISA. Adding IgA to a conventional IgM and IgG serological test improves sensitivity.

STATISTICAL ANALYSIS USED

The collected donor data were analyzed with IBM SPSS Statistics software. Pearson's Chi-square test and Fisher's exact test were used. P = 0.05 was considered statistically significant.

RESULTS

IgG seropositivity among the donors was 58.8%, and IgM + IgA seropositivity was 29.6%. There was no statistically significant difference in the COVID-19 IgG/IgM + IgA seropositivity status with age, gender, blood group, occupation, or socioeconomic status. The IgG and IgM/IgA/IgG ELISA kits showed a difference of 13 cases which could be attributed to the higher sensitivity of IgG alone ELISA kit. This increased the seroprevalence by 3%.

CONCLUSION

The majority of donors were either IgG or IgM and IgA positive, despite remaining asymptomatic. The seropositivity rate coincided with the COVID-19 surge among population.

Seroprevalence of COVID-19 in Blood Donors: A Systematic Review and Meta-Analysis

Introduction

Determining the prevalence of SARS-CoV-2 in blood donors makes the control of virus circulation possible in healthy people and helps implement strategies to reduce virus transmission. The purpose of the study was to examine the seroprevalence of COVID-19 in blood donors using systematic review and meta-analysis.

Materials and Methods

The electronic databases PubMed, Scopus, Web of Science, and the Google Scholar search engine were searched using standard keywords up to 2022-04-26. The variance of each study was calculated according to the binomial distribution. Studies were combined according to the sample size and variance. Q Cochrane test and I2 index were used to examine the heterogeneity of the studies. Data analysis was performed in STATA 14 software, and the significance level of the tests was P < 0.05.

Results

In the 28 papers examined with 227894 samples, the seroprevalence of COVID-19 in blood donors was 10% (95% CI: 9%, 11%), estimated 5% (95% CI: 4%, 7%) among men and 6% (95% CI: 4%, 7%) among women. This rate in different blood groups was as follows: A 12% (95% CI: 10%-14%), B 12% (95% CI: 10%-15%), AB 9% (95% CI: 7%-12%), and O 13% (95% CI: 11%-16%). The seroprevalence of COVID-19 in blood donors in North America 10%, Europe 7%, Asia 23%, South America 5%, and Africa was 4%; Moreover, the seroprevalence of IgG antibodies was estimated to be 23% (95% CI: 18%-29%) and IgM 29% (95% CI: 9%-49%).

Conclusion

The highest prevalence of COVID-19 serum in women blood donors was among blood group O and Asia. The seroprevalence of IgG and IgM antibodies was high too.

SARS-CoV-2 Neutralizing Capacity among Blood Donors without prior COVID-19 symptomatic history vs Blood Donors with prior COVID-19 symptomatic history: A Comparative Study

Introduction

Though moderate to severely ill COVID-19 patients are being treated using COVID Convalescent plasma across the world, there is a lack of standardization or information about the relative neutralizing capacity of antibodies from convalescent plasma donors. The current study aimed to compare the neutralizing antibody inhibition levels between COVID-Convalescent plasma from apheresis donors who had symptomatic COVID-19 history and asymptomatic blood donors, i.e., whole blood donors without prior any COVID-19 positive diagnosis nor symptoms/contact history related to COVID-19.

Methods

Observational study conducted at the Blood Centre, Tertiary Care Hospital, South India on blood donor samples during the period July–December 2020. A total of 90 samples (43 convalescent plasma donors and 47 whole blood donors) were tested for SARS-CoV-2-IgG and Neutralising antibodies.

Results

No significant difference in neutralization capacity was observed between these symptomatic vs. asymptomatic donors. Also, inhibition % appeared similar in the two groups with respect to age, gender, blood group, donation status, or type of donation without any statistical significance. On analyzing the correlation between the SARS-CoV-2-IgG levels and neutralizing antibodies among the WBD and CCP, both the groups showed a positive correlation, while neutralizing antibodies showed a significant correlation with SARS-CoV-2-IgG levels among the whole blood donors (Pearson correlation P = 0.000).

Conclusion

No significant difference in neutralizing antibody capacity was observed in asymptomatic whole blood donors and convalescent plasma donors. Therefore, donors having adequate levels of SARS-CoV-2-IgG antibody levels on screening can be considered for convalescent plasma donation irrespective of prior COVID-19 diagnosis or COVID-related symptoms.