In search of protective antibody for coronavirus disease 2019: A retrospective study
More details
Hide details
Medica Superspeciality Hospital, Kolkata, India
Department of Pharmacology, Burdwan Medical College, Burdwan, India
Department of Clinical and Experimental Pharmacology, School of Tropical Medicine, Kolkata, India
Department of Pharmacology, Netaji Subhash Medical College and Hospital, Bihta, Patna, India
Shambo Samrat Samajdar   

Department of Clinical and Experimental Pharmacology, School of Tropical Medicine, 108, Chittaranjan Avenue, Kolkata – 700073, West Bengal, India.
Submission date: 2021-11-22
Final revision date: 2022-02-23
Acceptance date: 2022-02-23
Online publication date: 2022-04-04
The search for a protective antibody titer level to prevent coronavirus disease 2019 (COVID-19) infection, progression, and death is far from over. To date, no specific cut-off values have been established for these protective antibodies or neutralizing antibody (NAb) titers. NAb titers inhibit viral replication.

To find out the prevailing NAb titre which might give protection from COVID-19 infection, or complication arising out of it.

Material and methods:
The data of COVID-19 patients with NAb titers who underwent reverse transcription polymerase chain reaction and presented with mild symptoms within 3 days after receiving the results were analyzed. The data were obtained from the clinic’s electronic database. Of the recruited patients, 63 were included in the final analysis. All statistical analyses were performed using SPSS v. 21.

Results and discussion:
A highly significant correlation (negative) existed between circulating NAb titer and duration of fever (P < 0.001); a positive significant correlation existed between the period from the 1st vaccine dose to the period of infection and the NAb titer level (P < 0.001). The NAb titer was significantly higher in the group that received both doses (P = 0.00016). Death and admission due to progression to moderate COVID-19 occurred in the group with a NAb titer of less than 10 U/L.

The risk of complications and death due to COVID-19 may increase if the protective antibody level remains less than 10 U/L. The sample size used in this study was relatively small; therefore, this finding cannot be generalized. Hence, more robust studies should be performed to determine the appropriate protective NAb titer levels.

The authors would like to acknowledge the help of Editage in helping perform editing.
The authors declare that they have no conflict of interest.
Khoury DS, Cromer D, Reynaldi A, et al. Neutralizing antibody levels are highly predictive of immune protection from symptomatic SARS-CoV-2 infection. Nat Med. 2021;27(7):1205–1211.
WHO. WHO COVID-19 Dashboard. Published 2021. Accessed: August 11, 2021.
Roy S. Journey so far with COVID 19 – a comprehensive review. Eur J Clin Exp Med. 2020;18(4):303–317.
NIH. Coronavirus disease 2019 (COVID-19) treatment guidelines covid-19 treatment guidelines. https://files.covid19treatment.... Accessed: August 11, 2021.
Roy S. COVID-19 reinfection in the face of a detectable antibody titer. Cureus. 2021;13(3):e14033.
Poland GA, Ovsyannikova IG, Kennedy RB. SARS-CoV-2 immunity: review and applications to phase 3 vaccine candidates. Lancet. 2020;396(10262):1595–1606.
Ogega CO, Skinner NE, Blair PW, et al. Durable SARS-CoV-2 B cell immunity after mild or severe disease. J Clin Invest. 2021;131(7):e145516.
CDC. Information for laboratories about coronavirus (COVID-19). 2020 Centers for Disease Control and Prevention. Accessed: August 11, 2021.
Gharbharan A, Jordans CCE, GeurtsvanKessel C, et al. Effects of potent neutralizing antibodies from convalescent plasma in patients hospitalized for severe SARS-CoV-2 infection. Nat Commun. 2021;12(1):3189.
Qu J, Wu C, Li X, et al. Profile of immunoglobulin G and IgM antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Clin Infect Dis. 2020;71(16):2255–2258.
Wolfel R, Corman VM, Guggemos W, et al. Virological assessment of hospitalized patients with COVID-2019. Nature. 2020;581(7809):465–469.
Garcia-Beltran WF, Lam EC, Astudillo MG, et al. COVID-19-neutralizing antibodies predict disease severity and survival. Cell. 2021;184(2):476–488.e11.
Addetia A, Crawford KHD, Dingens A, et al. Neutralizing antibodies correlate with protection from SARS-CoV-2 in humans during a fishery vessel outbreak with a high attack rate. J Clin Microbiol. 2020;58(11):e02107–02120.
Pray IW, Gibbons-Burgener SN, Rosenberg AZ, et al. COVID-19 outbreak at an overnight summer school retreat – Wisconsin, July-August 2020. MMWR Morb Mortal Wkly Rep. 2020;69(43):1600–1604.
Stangroom J. Mann-Whitney U Test Calculator. https://www.socscistatistics.c.... Accessed: February 15, 2022.
Ho MS, Chen WJ, Chen HY, et al. Neutralizing antibody response and SARS severity. Emerg Infect Dis. 2005;11(11):1730–1737.
Aziz NA, Corman VM, Echterhoff AKC, et al. Seroprevalence and correlates of SARS-CoV-2 neutralizing antibodies from a population-based study in Bonn, Germany. Nat Commun. 2021;12:2117.
Feng S, Phillips DJ, White T, et al. Correlates of protection against symptomatic and asymptomatic SARS-CoV-2 infection. medRxiv. 2021.06.21.21258528.
Dispinseri S, Secchi M, Pirillo MF, et al. Neutralizing antibody responses to SARS-CoV-2 in symptomatic COVID-19 is persistent and critical for survival. Nat Commun. 2021;12(1):2670.
Chen W, Zhang J, Qin X, et al. SARS-CoV-2 neutralizing antibody levels are correlated with severity of COVID-19 pneumonia. Biomed Pharmacother. 2020;130:110629.
FDA. Antibody testing is not currently recommended to assess immunity after COVID-19 vaccination: FDA safety communication. Published May 19, 2021.
Bhaskaran K, Bacon S, Evans SJ, et al. Factors associated with deaths due to COVID-19 versus other causes: population-based cohort analysis of UK primary care data and linked national death registrations within the OpenSAFELY platform. Lancet Reg Health Eur. 2021;6:100109.
Lanini S, Montaldo C, Nicastri E, et al. COVID-19 disease-temporal analyses of complete blood count parameters over course of illness, and relationship to patient demographics and management outcomes in survivors and non-survivors: A longitudinal descriptive cohort study. PLoS One. 2020;15(12):e0244129.
Zeng ZY, Feng SD, Chen GP, et al. Predictive value of the neutrophil to lymphocyte ratio for disease deterioration and serious adverse outcomes in patients with COVID-19: a prospective cohort study. BMC Infect Dis. 2021;21:80.
Moutchia J, Pokharel P, Kerri A, et al. Clinical laboratory parameters associated with severe or critical novel coronavirus disease 2019 (COVID-19): a systematic review and meta-analysis. PLoS One. 2020;15(10);e0239802.
Roy S, Samajdar SS, Tripathi SK, Mukherjee S, Bhattacharjee K. Outcome of different therapeutic interventions in mild COVID19 infection. J Clin Immunol Microbiol. 2021;2(2):1–10.
Yang J, Zheng Y, Gou X, et al. Prevalence of comorbidities and its effects in coronavirus disease 2019 patients: a systematic review and meta-analysis. Int J Infect Dis. 2020;94:91–95.
Cioni G. The role of angiotensin-converting-enzyme 2 in the age- and sex related poor prognosis of COVID-19. A comment on recent findings on novel coronavirus infection by SARS-CoV-2. Pol Ann Med. 2020;27(1):85–87.