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 Table of Contents  
Year : 2022  |  Volume : 34  |  Issue : 2  |  Page : 176-179

Quantitative estimation of anti-spike SARS-CoV-2 IgG antibody response after covishield vaccination in healthcare workers

Department of Oral Medicine and Radiology, Maharana Pratap College of Dentistry and Research Centre, Gwalior, Madhya Pradesh, India

Date of Submission10-Dec-2021
Date of Decision30-May-2022
Date of Acceptance03-Jun-2022
Date of Web Publication22-Jun-2022

Correspondence Address:
Mayuri Jain
Associate Professor, Department of Oral Medicine and Radiology, Maharana Pratap College of Dentistry and Research Centre, Gwalior – 474 011, Madhya Pradesh
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/jiaomr.jiaomr_338_21

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Background: Most studies of COVID vaccination focused on cell-mediated immunity and serum IgG antibodies, overlooking the role of anti-Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) neutralizing IgA antibodies in preventing viral infection. SARS-CoV-2 vaccine generates variable Anti-Spike IgG responses following one or two vaccine doses in almost all individuals for protection. Aim: The study aimed to quantify and estimate the Anti-Spike SARS-CoV-2 IgG antibody response after the second dose of the Covishield vaccine in healthcare workers (HCWs) over the time frame of one, three, and six months. Material and Methods: 30 HCWs who had received both doses of the Covishield vaccine were selected and divided into three groups based on the time elapsed after the second dose of vaccine for serological analysis. Post-vaccination antibody responses were measured using the SARS-CoV-2 IgG Quantitative assay (detection threshold: ≥50 AU/ml) using chemiluminescent microparticle immunoassay (CMIA). Data were analyzed using the Kolmogorov-Smirnov test, Kruskal-Walli's test, and Mann-Whitney U test. Result: Vaccination leads to measurable anti-spike IgG antibodies in HCWs. Only 1 individual was seronegative. The highest antibody titer was reported after one month of the second dose (3615.3 AU/ml). The lowest antibody titer (491.5 AU/ml) was seen after six months of the second dose of Covishield is statistically significant. Conclusion: Anti-Spike SARS-CoV-2 IgG antibody determination is necessary for an immune response after vaccination. This titer decreases with time consequently as the duration after the second dose of the Covishield vaccine increases. This helps assess the requirement of a booster dose for effective immunity against coronavirus.

Keywords: Anti-Spike SARS-CoV-2, COVID-19, covishield, IgG antibodies, vaccination

How to cite this article:
Goyal M, Jain M, Patel N, Sharma A. Quantitative estimation of anti-spike SARS-CoV-2 IgG antibody response after covishield vaccination in healthcare workers. J Indian Acad Oral Med Radiol 2022;34:176-9

How to cite this URL:
Goyal M, Jain M, Patel N, Sharma A. Quantitative estimation of anti-spike SARS-CoV-2 IgG antibody response after covishield vaccination in healthcare workers. J Indian Acad Oral Med Radiol [serial online] 2022 [cited 2023 Jan 31];34:176-9. Available from: http://www.jiaomr.in/text.asp?2022/34/2/176/347926

   Introduction Top

The emerging coronavirus disease has flounced all over the world. The first case was reported in Wuhan city (China) in December 2019.[1] The causative virus of this originated in bats and was transmitted to humans through the Wuhan seafood market.[2] The virus spreads from inhalation of infected droplets, aerosols, or direct contact with infected objects/surfaces.[3] The symptoms range from fever, cough, breathlessness, pneumonia, acute respiratory distress syndrome, and multi-organ dysfunction, with a mortality rate of 2 to 3%.[3],[4] Vaccination is considered the most effective means to prevent the risk of contracting a disease or developing severe forms of infection-related illness.[5] As vaccines for COVID-19 are being introduced worldwide, clinicians are interested to know the effectiveness of the vaccination and the necessity of booster doses in the future.[6] Here we study quantitative estimation of post-vaccination-induced ant spikes Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) IgG antibody response after the second dose of Covishield vaccine in 30 healthcare workers.

   Material and Methods Top

(a) Ethics: The study was conducted in the department of Oral Medicine and Radiology, with the informed consent of all participants. The declaration of Helsinki conducted the study (1975), and the Ethical institutional committee cleared its protocols.

(b) Study Design: This observational study evaluated the Covishield vaccine-induced antibody responses in 30 HCWs divided into three groups according to antibody responses after the second dose of vaccine in the first, third, and sixth month.

Sample size estimation: The sample size estimation was done using G power statistics. The test family was the F test. Software version is based on parameters or data from the previous literature. Using this software, the minimum required sample size was 15. To remove errors and attrition in the clinical trial, the sample size was proposed to include 30 subjects (i.e., 10 subjects per group). The study subjects were divided into groups. Each group comprises 10 subjects. Group 1 consists of individuals who received a second dose of the Covishield vaccine one month ago. Group 2 consists of individuals who received the second dose of the Covishield vaccine three months ago. Group 3 consists of individuals who received a second dose of the Covishield vaccine six months ago.

Inclusion and Exclusion criteria:

  • Subjects within the age range of 21-50 years who voluntarily accepted only the Covishield vaccine the second dose were included in the study.
  • Subjects with Covaxin dose, Covishield vaccine first dose, and another vaccine were excluded from the study.

Sample collection: Under aseptic conditions, 2 ml of Venous Blood was collected using absolute alcohol and bi-ended needle with a connector and was drawn directly into yellow capped sterile vacuumed Clot Activator Tubes (CAT), which contained Gel for serum separation. The blood was allowed to clot for 60 min and then centrifuged at 3000 rpm for 5 min. Serum was separated using a pipette and stored in a separate container. The samples were stored in a deep freezer at –20°C. Quantitative post-vaccine anti-spike SARS CoV-2 IgG antibody status was assessed using Chemiluminescent Microparticle Immuno Assay (CMIA). The assay cut-off is ≥50 AU/ml, with linear quantification of measurable results from 50 to 40,000 AU/ml. (reported by the manufacturer)

(c) Statistics: The statistical analysis was performed using the International Business Machines Corporation statistical package for social science version 20 (IBM, Armonk, New York). The data were analyzed for probability distribution using the Kolmogorov-Smirnov test. Non-parametric test of significance was applied. The inter-group comparisons were made using the Kruskal-Walli's and Mann-Whitney U tests. P value < 0.05 was considered statistically significant.

   Result Top

The study showed that the antibody titer of patients belonging to three groups based on the time elapsed after vaccination was found to be significant. The antibody titer of group one was 3615.3 (1507.45-5237.225) Arbitrary unit (AU/ml), group 2 was 996.35 (186.575-2968.275) AU/ml, and group 3 was 491.5 (66.175-1571.325) AU/ml. [Table 1]/[Figure 1]. These values differ significantly among the group, with the highest value being in group 1 and the lowest in group 3.
Figure 1: Inter-group comparison of antibody titer of participants belonging to different groups based on the time elapsed after vaccination.

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Table 1: Comparison of antibody titer of patients belonging to three groups based on the time elapsed after vaccination

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Intergroup comparison revealed a significant difference in the antibody titers. The antibody titer of patients of group 2 and 3 participants was significantly less than the antibody titer of group 1 participants. However, no statistically significant difference in antibody titer can be seen in groups 2 and 3 [Table 2].
Table 2: Intergroup comparison using post hoc analysis

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A comparison of age in gender and antibody titers using Mann-Whitney test revealed the median age of males and females and their antibody titers did not differ significantly; however, the values of antibody titers were more in females [Table 3]
Table 3: Comparison of age and antibody titers between two genders

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   Discussion Top

The present study assesses the humoral immune response developing after the Covishield vaccine by determining the Anti-Spike SARS-CoV-2 IgG neutralizing antibody in serological samples of 30 HCWs. COVID-19 has a serious impact on one's health, social life, and economy. Vaccination seems to play a crucial role in diminishing the outcomes of the current pandemic. Many epidemiological studies suggested a strong correlation between vaccine distribution and SARS-CoV-2 positive cases, hospitalization, and death reduction.[7] Circulating Anti-Spike SARS -CoV-2 IgG antibodies would act in synergy to deactivate the virus within or outside the host cells.[8] Our study noted that vaccination leads to measurable anti-spike IgG antibodies in 30 HCWs; only one HCW was seronegative (<50 AU/ml) as the assay cut-off results from 50 to 40,000 AU/ml. Our study shows a progressive decrease in antibody titer in individuals having both the doses of the Covishield vaccine with time. It has been seen that the development of antibodies was maximum after one month, with antibody titer being 3615.3 AU/ml (1507.45-5237.225), followed by three months, that is, 996.35 (186.575-2968.275) AU/ml and six months, that is, 491.5 (66.175-1571.325) AU/ml [Table 1]/[Figure 1]. When we compared the antibody titers among the three groups, the difference was statistically significant between group 1 and group 2 and group 1 and group 3 (p value < 0.05). The antibody titers differ between groups 2 and 3, but it was not significant. A study by Mat Makowski et al.[9] on antibody persistence through six months assumes a steady decay rate of neutralizing antibodies that decrease over time; similar observations were seen in our study. As the time duration increased after the second dose of the vaccine, there was a gradual decline in antibody titer. It has also been noted that different vaccines induce different antibody responses in the individuals, also the immune response varies with the history of previous infections. A study compared the SARS-CoV-2 Antibody Response following Vaccination with Comirnaty (Pfizer-BioNTech) and Moderna. Higher antibody titers were seen in subjects vaccinated with two doses of Moderna than those vaccinated with Comirnaty (Pfizer-BioNTech). Those infected subjects previously had higher antibody titers than uninfected subjects. In both groups, those vaccinated with the Moderna vaccine had higher antibody titers compared with those vaccinated with Comirnaty (Pfizer-BioNTech).[10] A comparison of age and gender and antibody titers using Mann-Whitney test revealed the median age of males was 30.0 (23.5-32.5) years and females were 29.0 (24.0-31.0) years, and antibody titers of males were 1569.2 (345.95-3768.9) AU/ml and females was 3200.6 (272.5-4467.0) AU/ml does not differ significantly, however, the values of antibody titer were more in females [Table 3] suggesting that antibody response was better in females than males. Studies show that humoral immune response is age-dependent and gender-dependent; it peaks at the highest level (independently of age or gender) 2 weeks post the second dose and starts to decline after four weeks. The data by Terpos Evangelos et al.[11] supports increased production of antibody titers after the first dose, which is similarly more robust in younger ages and females. These findings indicate that the second timely vaccination is critical, especially in the elderly. Another study revealed lower seroconversion rates in older HCWs (i.e., ~60 years). The Pfizer-BioNTech trial reported antibody concentrations were higher in younger (18-55 years) vs. older (56-85 years) participants, but however high seroconversion rates were observed in Oxford-AstraZeneca trials involving older adults (≥65 years) after their first and second doses.[12],[13] Another important aspect that has emerged from the studies is that the relative increase in anti-spike SARS-COV-2 antibody levels were inversely correlated with age. Our results were consistent with the results of other studies; however, few limitations could be observed in the study. The study's sample size was small, which could have affected the outcome. Also, the individuals included in the study were of a younger age group. Therefore, future studies with larger sample sizes and age groups should confirm the findings. It should be kept in mind that the generation of antibodies in an individual is multifactorial, affected by age, individual immune response, gender, previous infections, and the vaccine's dosing schedule. These parameters should be considered when assessing the potential of antibody development following vaccination. Study limitations include the smaller sample size, and as we have done in HCWs, it should be done in the general community, including children and older age groups. Further large-scale studies will be required to assess the protection from infection varies by antibody titer and regulate the period of antibody responses.

   Conclusion Top

Hence the study suggests that neutralizing antibody titer decreases with time after the increased duration of the second dose of the Covishield vaccine. Further prospective studies will be required for the proper estimation of changes in the immunity profile of an individual with the administration of various vaccine regimens. It is not clear how long protection might last with a single dose because follow-up is limited to the periods, and, for this reason, the second dose of vaccine is recommended. A second dose of Covishield induces increased neutralizing antibody levels and is probably necessary for long-lasting protection. With the evidence available, it is anticipated that a booster dose should be made mandatory to potentiate the long-lived immunity.

Patient consent form

Informed consent was obtained from all individuals included in this study.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

   References Top

Wang C, Horby PW, Hayden FG, Gao GF. A novel coronavirus outbreak of global health concern. Lancet 2020;395:470-3.  Back to cited text no. 1
Xinhua. China's CDC detects many new coronaviruses in the South China seafood market in Wuhan. 2020. Available from: https://www.xinhuanet.com/2020-01/27/c_1125504355.htm. [Last accessed on 2020 Feb 20].  Back to cited text no. 2
Singhal T. A review of corona virus disease-2019 (covid-19). Indian J Pediatr 2020;87:281–6.  Back to cited text no. 3
Coronavirusrus Outbreak. 2020. Available from: https://www.worldometers. info/coronavirus/. [Last acessed on 2020 Feb 23].  Back to cited text no. 4
Gian Luca S, Henry B, di Piazza G, Laura P, De Nitto S, Luca G, et al. Anti-spike S1 IgA, anti-spike trimeric IgG, and anti-spike RBD IgG response after BNT162b2 Covid-19 mRNA vaccination in healthcare workers. J Med Biochem 2021;40:327-34.  Back to cited text no. 5
Eyre DW, Lumley SF, Wei J, Cox S, James T, Justice A, et al. Quantitative SARS-CoV-2 anti-spike responses to Pfizer BioNTech and Oxford AstraZeneca vaccines by previous infection status. J Clin Microbiol Infect 2021;27:1516.e7–14.  Back to cited text no. 6
Borchering RK, Viboud C, Howerton E, Smith CP, Truelove S, Runge MC, et al. Modeling of future COVID19 cases, hospitalizations, and deaths, by vaccination rates and nonpharmaceutical intervention scenarios-United States. MMWR Morb Mortal Wkly Rep 2021;70:719–24.  Back to cited text no. 7
Xiaojie S, Yu L, Lei Y, Guang Y, Min Q. Neutralizing antibodies targeting SARS-CoV-2 spike protein. Stem Cell Res 2020;50:102125.  Back to cited text no. 8
Makowski M, Connell SO, McDermott AB, Flach B, Ledgerwood JE, Mascola JR, et al. Antibody persistence through 6 months after the second dose of m-rna-1273 vaccine for covid-19. N Engl J Med 2021;384:2259-61.  Back to cited text no. 9
Steensels D, Pierlet N, Penders J, Mesotten D, Heylen L. Comparison of SARS-CoV-2 antibody response following vaccination with BNT162b2 and mRNA-1273. J Am Med Assoc 2021;326:1533-5.  Back to cited text no. 10
Evangelos T, Ioannis P, Filia A, Ioanna C, Aimilia D, Nefeli M, et al. Age-dependent and gender-dependent antibody responses against SARS-CoV-2 in health workers and octogenarians after vaccination with the BNT162b2 mRNA vaccine. Am J Hematol 2021;96:E257-9.  Back to cited text no. 11
Department of Health and Social Care (DHSC). Public assessment report authorization for a temporary supply. COVID-19 mRNA Vaccine BNT162b2. Available from: https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/944544/COVID19_Mrna_Vaccine_BNT162b2UKPAR_PFIZER_BIONTECH_15.120.2020.pdf.  Back to cited text no. 12
Department of Health and Social Care (DHSC). Public assessment report authorization for a temporary supply. COVID-19 Vaccine Astra Zeneca. Covid 19 2021. Available from: https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/963928/UKPAR_COVID_19_Vaccine_AstraZeneca_23.02.2021.pdf.  Back to cited text no. 13


  [Figure 1]

  [Table 1], [Table 2], [Table 3]


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