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Molecular Identification and Seroprevalence of SARS-CoV2 IgG antibody among Health Care Workers in Peshawar

Pakistan

Mohsina Haq1*, Ihteshamul Haq2*, Fazli zahir3,Abbas Saleem khan4, Shabir Ahmad5, Tanveer Tara6, Muhammad Naveed Akhtar7, Kamran Shah8, Hina Ali5, Bahar Ali9,Seema zubair10, Zeeshan Ahmad11, Said Munir5, Abdul

Samad12,

1. Department of Microbiology Peshawar Medical college, Ripah International university Islamabad 2. Department of Biotechnology and Genetic Engineering Hazara University Mansehra Kp Pakistan,

3. Department of Allied Health Science Iqra National University Peshawar Kp Pakistan 4. Oral Peshawar Dental College , Ripah international university Islamabad Pakistan 5. Institute of Biological Science and Information Technology Peshawar Kp Pakistan 6. Department of Medical Lab Technology National skills university Islamabad Pakistan

7. Department of Biochemistry Hazara university mansehra Kp Pakistan

8. Department of Medical Lab Technology Sarhad University of Science and Information Technology Peshawar Kp Pakistan

9. College of Plant Science & Technology, Huazhong Agricultural University, Wuhan, Hubei, China 10. Department of statistics, mathematics and computer science, The university of Agriculture, Peshawar, Kp

Pakistan

11. Department of Microbiology Hazara University Mansehra Kp Pakistan 12. Department of Phlebotomy Islamabad Diagnostic Center Islamabad, Pakistan

Corresponding Author: Ihteshamul Haq2*

Email Address:[email protected] Co-Corresponding Author: Mohsina Haq1*

Email Address: [email protected]

Abstract

Covid19, the disease caused by SARS-CoV2, spread across the world during 2020. Health Care Workers (HCWs) are at higher risk for Covid19. Sero-surveillance among HCWs using IgG antibodies can add further value to the scientific findings. Purpose of the Current study to estimate seropositivity among HCWs and to correlate it with various factors affecting seropositivity.

Population based large scale Sero-surveillance among HCWs was carried out during second half of August‟2020 in Peshawar Pakistan using “Covid-Kavach” IgG Antibody Detection ELISA kits.

Seropositivity among HCWs was estimated and compared with various demographic & other factors to understand their infection & immunity status. Proportions and Z-test were used for statistical finding of result. As on August‟2020, Seropositivity among HCWs at Peshawar is 23.65% (95% Confidence Interval 21.70–25.73%). Seropositivity of 25.98% (95%CI 23.47–

28.66) among female HCWs is significantly higher than 19.48% (95%CI 16.53–22.80) among male HCWs. The zone wise positivity among HCWs closely correlate with cases reported from the respective zone. The sero-positivity among HCWs from the earliest and worst affected zones has lower level of seropositivity as compared to the zones affected recently. This might be pointing to- wards the fact that the IgG Antibodies may not be long lasting. As on August 2020, the seropositivity of 23.65% in HCWs indicates high level of disease transmission and higher risk

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of infection among HCWs in Peshawar. The seropositivity is significantly higher among female HCWs. Zone wise seropositivity, closely correlate with the reported cases from the respective zone. Their comparison also indicates the possibility of reducing IgG seropositivity, which necessitates further in-depth scientific research to generate greater scientific evidences

Introduction

Covid19, the disease caused by SARS-CoV2, spread across the world during 2020.1 In view of the asymptomatic infection of Covid19, we cannot rely on the data of identified cases as those who exhibit symptoms are more likely to get tested than asymptomatic individuals.2Sero- surveillance uncover the asymptomatic, subclinical infection and helps in understanding the disease transmission dynamics in a better way for planning an appropriate public health response.3Multiple sero-surveillance studies conducted during the pandemic have focused on antibodies against SARS-CoV2 in the general population.4,5 HCWs are exposed to suspected/confirmed cases and their contacts as part of their job-profile. This occupational exposure put them at a higher risk of infection.6 Frontline HCWs working in hospitals had a significantly higher Seroprevalence than HCW in other settings.7 None the less, HCWs working in the field, both from public sector and private sector, are still at higher risk of infection. These HCWs could be a source of infection as they can transmit the infection. Thus, Seroprevalence among field level HCWs is a crucial indicator giving better scientific insight into disease situation. Peshawar city was one of the earliest cities to witness the high number of cases during the initial months of the pandemic in India. We carried out a population based sero-surveillance during the second half of August‟2020. In this sero- surveillance, apart from the general population, HCW were also included as an additional category along with cases & contacts of cases. This article focuses and describes only the “HCWs” component of the sero-surveillance. Keeping estimation of Seroprevalence among HCWs as our primary objective, we also checked the correlation of seropositivity with various demographic and other factors affecting their immunity.

Materials and methods

Taking Permission from the administration of Lady Reading Hospital Peshawar for conducting IgG Antibody based ELISA test for Sero-surveys to monitor the pandemic, understand its progression and to take appropriate corrective public health measures. At Lady Reading Hospital Peshawar we conducted a sero- survey using population based stratified sampling during second half of August 2020. Result of the earlier sero-survey in general population of Peshawar was used for the purpose of calculating the sample size for the present study. Ward/Urban Primary Health Centre (UPHC) wise required minimum sample size for the general population category was determined based on population proportion with 95% confidence level with 1% margin of error. Along with the general population category, HCWs were also enrolled separately as an additional category along with cases and contact of cases. The sample size for the “HCWs” category was decided as at least 10% of general population sample target. This sample size was calculated for each ward/UPHC, and thus, the sample size for HCWs was also based on population proportion “Covid-Kavach” (Anti-SARS CoV2 IgG Antibody Detection capture ELISA) kits developed and manufactured by Zydus Diagnostics &

validated by National Institute of Virology, Pune, India was used for the purpose of this study. ICMR

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= =

±

±

±

±

has permitted its use for sero-surveillance of SARS-CoV2 as its results are quite reliable with sensitivity of 92.37% and specificity of 97.9% as per the validation reports.9 The manufacturer reported no cross-reactivity with other viruses in the serum from real-time RTPCR confirmed patients of various other infections. Testing procedures were followed as per the manufacturer‟s instructions. There are 75 UPHCs within 48 wards, across 7 zones in Peshawar. There are various categories of health workers posted at these UPHCs. There are other health care workers from the field area of UPHCs, who are working at private dispensaries, hospitals, other health care setup etc.

All such HCWs were eligible to get enrolled in the study in the HCW category. All UPHCs tried to enroll all such eligible under the Health Care Worker category for the purpose of serosurveillance.

Thus, the sample included a mix of doctors, nurses, paramedical, field level health care workers etc all directly or indirectly associated with the health care field. All these health care workers were enrolled without any bias of designation, work setting or affiliations, since estimation of Seroprevalence among HCWs was the primary objective. The study was carried out after the approval of ethics committee of Lady Reading Hospital Peshawar. Written informed consent was taken for the purpose of the study from all the participants before enrollment. Strict Confidentiality was ensured at all levels. For the purpose of testing and standardization, only those laboratories with national level accreditation and state of the art facilities and equipment were approved for testing the samples. To reduce the sample rejection rate, SST-Gel Vacutee was used for the collection of blood samples. Microsoft Excel and Epi-Info was used for the purpose of data management. The crude positivity in HCWs was considered as an indicator for the current level of immunity among field level HCWs. In-depth analysis of the data was carried out with focus on comparing seropositivity among HCWs with various demographic and other factors. Simple proportions and appropriate statistical tests were used wherever required. In this article, we have tried to focus only on the analysis of Seroprevalence among HCWs. The comparison of Seroprevalence among HCWs with the Seroprevalence among general population and other categories have been addressed in other articles and not discussed at stretch in the present study. We here with share the findings of our results for the detailed insight by the scientificcommunity.

Results

A total of 1710 (1098 female, 612 male) samples from HCWs were collected out of which 2 samples were rejected, one each from both the sex groups. Results were thus available for 1708 samples.

From these results 1288 (75.41%) were negative and 16 (0.94%) had indeterminate results. Thus, a total of 404 results were positive for the IgG antibodies against SARS-CoV2 giving an overall positivity of 23.65% [95% Confidence Interval (CI) 21.70–25.73%]. Detailed analysis of 1708 HCWs (Table- 1) show that there were 1097 female and 611 male HCWs for whom results were available. A total of 285 samples were positive among female giving a positivity rate of 25.98%

[95%CI 23.47–28.66%] whereas 119 samples were positive among male giving a positivity of 19.48% [95%CI 16.53–22.80%]. The percentage positivity is higher among female HCWs as compared to the male HCWs and the difference is statistically significant (Z=3.03, P= 0.002). The age distribution of the HCWs typically follows age-heaping bias (data not shown, only grouped data shown in Table- 1) as the age of the enrolled HCWs were approximate as replied by them and not verified with any official document. The age of the HCWs ranged from 16 to 82 years with a mode of 25, median of 33 and an average of 34.84 10.64 years. Among the sample, the mean age of

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females was 36.21 10.29 years whereas the mean age of males is 32.38 10.83 years. Considering the ±

Sero-positive HCWs, the mean age for females was 37,25, 10,19 years where as that of male is 31,55 10,31 years. The age group wise analysis of seropositivity among HCWs (Fig. 1) shows that the lowest seropositivity is for the 10–19 years age group (16.67%) and the highest seropositivity is for 50–59 years age group (27.22%). The linear trend line shows increasing trend from around 20%–

25% as the age-group increases from 10-19 to 60–69 years. When the same comparison of age-group and Sero-positivity is done for both the sex groups (Fig. 2) it shows that female HCWs have higher Sero- positivity for most of the age groups. The linear trend line when plotted for both the sex groups shows that while female HCWs have decreasing seropositivity as the age group increases male HCWs have increasing seropositivity with increase in the age group.The zone wise analysis of total tests and positive tests when compared to calculate percent positivity shows that the positivity in various zones varies widely. The zone wise positivity ranges from 10.14% to 29.72%. The zone wise positivity shows that the East Zone

Table-1 Analysis of Covid19 Sero-survey positivity in HCWs.

Female Male Total

Results Positive % Positivity

Results Positive % Positivity

Results Positive % Positivity

95% Confidence Interval

Total 1097 285 25.98 611 119 19.48 1708 404 23.65 21.67–25.70

Age group

10–19 6 2 33.33 18 2 11.11 24 4 16.67 04.74–37.38

20–29 327 67 20.49 294 64 21.77 621 131 21.10 18.07–24.48

30–39 342 102 29.82 174 31 17.82 516 133 25.78 22.19–29.72

40–49 291 73 25.09 59 11 18.64 350 84 24.00 19.82–28.74

50–59 118 38 32.20 51 8 15.69 169 46 27.22 20.67–34.59

60–69 11 2 18.18 13 3 23.08 24 5 20.83 07.13–42.15

70-79a 1 0 0.00 2 0 0.00 3 0 0.00 00.00–00.00

80-89a 1 1 100 0 0 0.00 1 1 100 02.50–100.0

Zone

CZ 109 25 22.94 59 13 22.03 168 38 22.62 16.53–29.70

EZ 269 83 30.86 54 13 24.07 323 96 29.72 25.00–34.92

NWZ 86 10 11.63 62 5 8.06 148 15 10.14 05.78–16.17

NZ 174 52 29.89 97 26 26.80 271 78 28.78 23.47–34.57

SWZ 79 16 20.25 69 4 5.80 148 20 13.51 08.45–20.10

SZ 210 55 26.19 122 22 18.03 332 77 23.19 18.97–28.02

WZ 170 44 25.88 148 36 24.32 318 80 25.16 20.70-30.20

Figure-1. Age group wise seropositivity in HCWs.

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Figure-2. Age group and sex wise seropositivity in HCWs.

(EZ–29.72%) had the highest seropositivity followed by North Zone (NZ–28.78%) whereas North West Zone (NWZ–10.14%) and the South West Zone (SWZ–13.51%) were the zones with lowest seropositivity. There is close correlation while comparing the reported covid19 cases and seropositivity in HCWs for each zone (Fig. 3). The zones with low number of reported cases (as on 31 Jul & 15 Aug „20) i.e., NWZ & SWZ, have lower seropositivity among HCWs whereas other zones with higher number of reported cases (either during recent past or at the beginning of the pandemic) have higher seropositivity among HCWs.

Discussion

Although the scientific community is aware of the general immune response after any viral infection, the information about immune response during and after covid19 infection is still largely evolving.10Multiple Sero-surveillance studies which have focused on antibodies against SARS- CoV2 among various categories have been found to be extremely useful in understanding the progress of the pandemic. Scientific studies have recommended continued surveillance through Seroprevalence studies to estimate and monitor the growing burden of Covid-19.11 The Seroprevalence varies markedly due to a variety of factors.12 For the same reason, understanding the factors affecting immunity-is extremely crucial while interpreting the results of the serosurveillance. The present study focuses on the seropositivity among HCWs from Peshawar city of \k\Kp, Pakistan. Seropositive HCWs are those who had been infected with SARS-CoV2 with/without symptom and who have developed IgG antibodies as a result of their clinical/subclinical infection, which is most likely to be due to an occupational exposure. Sero- prevalence among HCWs is an important indicator as it gives an idea of communicability of the infection & transmissibility of the infectious agent along with level of preventive/protective measures applied by the HCWs.As per our results, as of August ‟20, the average seropositivity for IgG antibodies against SARS-CoV2 among HCWs from Peshawar is 23.65% [95%CI 21.70–

25.73%]. As HCWs are aware of the transmission dynamics & provided with appropriate personal protective equipment, one would expect them to have low infection rate and thus with lower seropositivity. However, within just 4–5 months of pandemic with 23.65% positivity, a large number of HCWs have acquired symptomatic/asymptomatic infection and thus demonstrated antibodies. While comparing our study results with other studies among HCWs, the sero-prevalence

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varies greatly from around 1%–24.4%.13,14 However, depending on the type of setting, work profile, exposure risk etc t h e seropositivity varies a lot. So, comparison and interpretation of sero- positivity among HCWs must be extremely careful. Along with the seropositivity among HCWs (covered in this article), our study also measured seropositivity among general population. The seropositivity of 23.65% among HCWs, is quite close to the seropositivity among general population category (23.24%). The higher seropositivity among HCWs, as compared t o g e n e r a l p o p u l a t i o n i n d i c a t e w i d e s p r e a d d i s e a s e

Figure-3. Zone wise comparison of cases and seropositivity in HCWs.

transmission and justifies the high level of infection during the initial months of the pandemic in Peshawar as compared to other cities of Pakisan as also reported by NIH.15 Among the HCWs, females have higher positivity of 25.98% [95%CI23.47–28.66%] as compared to male HCWs who demonstrated positivity of 19.48% [95%CI 16.53–22.80%]. The significantly higher sero- positivity among female HCWs as compared to male HCWs, need to be scientifically analyzed in detail to identify reasons for the same. This is in contrast to other studies where the sex-wise difference is statistically not significant.16From the age analysis, the statistic of mode < median

<mean typically shows skewed distribution.17 This indicate that our study sample of HCWs included more of young adult HCWs as compared to the middle aged & elderly HCWs. Looking at the age-groups, 0–9 years age group is not applicable in HCWs. Only 4 HCWs above 70 years were enrolled and only 1 (from 8089 years age group) was sero-positive. So, we plotted the age-group wise analysis up to 60–69 years only, which covered most of the HCWs without any bias of the outliers.

The age group wise analysis

of seropositivity among HCWs (Fig. 1) shows that the seropositivity is seen in the range of 16.67%–

27.22%. The positivity is lower on both the extremes of the age groups, i.e. 10-19 and 60–69 years age groups. In both these age groups, the sample size is comparatively low. Moreover, health authorities at Peshawar have advised low risk work assignment to the 50 age groups particularly those HCWs with any of the known comorbid condition. So, in the HCWS with 50 age, there was reduced occupational exposure as compared to other HCWs, at least in the public health sector. Even

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in the private health care sector, during the early months of the pandemic, elderly health care workers particularly with comorbidity were avoiding practice and direct clinical exposure. All the above details could possibly explain the low seropositivity in the extremes of the age groups, from whatever little sample that we have enrolled. Seropositivity level is seen on higher side in the age groups representing young adults and middle aged HCWs. This may be related to their field work duty assigned to the health care workers in the public health sector. Even in the private sector, the young aged HCWs were more active in health care services and thus more at risk of having a contact and more likely to develop antibodies against SARS-CoV2 which reflected as seropositivity in the serosurveillance. While checking the trend of seropositivity with a linear trend line, it shows increasing seropositivity with increasing age group among HCWs. We noted that the scientific research studies have documented that young adults are more likely to be asymptomatic, have milder symptoms and for shorter duration, if at all, as compared to the elderly people.18–21 It is also documented that percent Sero conversion in asymptomatic cases is low.22 This phenomenon holds true not only for general population but also for HCWs and this may be the reason for higher Sero- conversion among middle aged as compared to the young adults, When the same comparison of age- group and sero-positivity is done for both the sex groups (Fig. 2) it shows that female HCWs have higher seropositivity for most of the age groups. The linear trend line when plotted for both the sex groups shows that female HCWs have decreasing seropositivity as the age group increases. On the other hand, male HCWs have increasing seropositivity with increase in the age group. This is a typical finding and in the absence of other details for the enrolled HCWs (designation, work setting or affiliations), we can only suggest that a further in-depth scientific study is required to find out the reasons for this difference.. HCWs are at a higher risk of contracting infection (& thus immunity) as the cases from their field-work area increases, and this holds true for public sector HCWs as well as Private sector HCWs, as both of them are involved in serving the local community. This is the reason why we compared the seropositivity among HCWs with the cases reported from their zone. So, although our sampling was population based & independent of the cases reported from the zone, but still, the positivity in HCWs closely correlate with the cases reported from their zone, higher for those zones with high current or past cases. The zone wise positivity ranged from 10.14% to 29.72%.Scientific studies have documented that antibodies take some time to develop after an infection, approximately 1–3 weeks, with an average 2 weeks (14 days).23,24 So, the rate of antibody positivity reflects the case scenario about 14 days prior to the study. Accordingly, since, our study was carried out during second half of August‟20, we took cases as on July end (around 2 weeks before the start of our study) & 15th August (around 2 weeks before the end of our study, coinciding with the starting point of our study). Comparing the zone wise cases with the seropositivity among HCWs (Figure- 3), it is seen that the zones with comparatively low number of cases [North West Zone (NWZ) & South West Zone (SWZ)] have low seropositivity among HCWs.

The comparison also shows that inspite of having similar number of cases in a narrow range, the sero-positivity among HCWs from the earliest and worst affected zones [Central Zone (CZ), South Zone (SZ)] have lower level of sero- positivity as compared to the zones affected recently [North Zone (NZ), East Zone (EZ)]. This might be pointing towards the fact that the IgG Antibodies may not be long lasting. Scientific studies have also documented declining level of antibodies, which vanishes over a period of time.25–27 This needs further research to cross verify with scientific evidence-to prove this observation.

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Conclusion

As on August 2020, the seropositivity of 23.65% in HCWs indicates high level of disease transmission and higher risk of infection among HCWs in Peshawar. The seropositivity is significantly higher among female HCWs. The zone wise seropositivity, closely correlate with the reported cases from the respective zone. Their comparison also indicates the possibility of reducing IgG seropositivity, which necessitates further in-depth scientific research to generate stronger scientific evidences.

References

1 Munster VJ, Koopmans M, Van Doremalen N, Van Riel D. PERSPECTIVE 692 A Novel Coronavirus Emerging in China A Novel Coronavirus Emerging in China-Key Questions for Impact Assessment. 2020.

2 Swaminathan A, Subramanian SV [cited 2021 Feb 12]. Reflections on Designing Population Surveys for COVID-19 Infection and Prevalence. vol. 42. GeroScience. Springer Science and Business Media Deutschland GmbH; 2020. https://doi.org/ 10.1007/s11357-020-00253-6, 1445–8. Available from:, [Internet].

3 Organization WH. Population-based Age-Stratified Seroepidemiological Investigation Protocol for COVID-19 Virus Infection. World Health Organization; 2020, 17 March 2020.

4 Qamar, Z., Anwar, F., Ahmad, R., & Haq, I. & Khan, J.(2021). Prevalence of Hepatitis C virus and determination of its genotypes in subjects of Tehsil Daggar District Buner, KP, Pakistan. Clinical Epidemiology and Global Health, 12(100809), 2. (8). https://doi.org/10.1038/s41591-020-0949- 6. Available from:, 1193–5.

5 Anwar, F., Tayyab, M., Haq, I., & Shah, O. U. (2021). Viral overload of COVID-19 pandemics:

Overweight people a soft target to get an infection. International Journal of Clinical Virology, 5(2), 070-071.

6 Anwarl, F., Khan, M., Rehman, N., Akbar, F., Ahmadl, S., Yousaf, M., ... & Zeeshan, M. (2021).

Review and forecasting on COVID-19 outbreak; An insight to in silico candidate drug discovery. Bioscience Research, 1198-1210.

7 Ahmad, I., Malik, M. S. M., Mustafa, A., Arif, H., Hassan, H., Shan, F., ... & Hassan, I. (2021).

COVID-19Awareness, Perceptions and Myths Among General Population of Pakistan During Pandemic. A survey-based study. Annals of the Romanian Society for Cell Biology, 25(6), 20086- 20097.

8 Ahmad, S. U., Khan, M. S., Jan, Z., Khan, N., Ali, A., Rehman, N., ... & Zahir, F. (2021). Genome wide association study and phylogenetic analysis of novel SARS-COV-2 virus among different countries. Pakistan Journal of Pharmaceutical Sciences, 34(4).

9 Haq, I., Zahir, F., & Khan, J. (2021). Epidemlogical Assessment and Frequency of Cardiovascular Diseases in Peshawar KP, Pakistan: A Cross-Sectional study. Annals of the Romanian Society for Cell Biology, 25(7), 1377-1388. Chirathaworn C, Sripramote M, Chalongviriyalert P, et al.

SARS-CoV-2 RNA shedding in recovered COVID-19 cases and the presence of antibodies against SARS- CoV-2 in recovered COVID-19 cases and close contacts. Thailand, April-June 2020 PLoS One [Internet]. 2020 Oct 1;15(10 October). Available from: https://pubmed.

ncbi.nlm.nih.gov/33119712/ [cited 2021 Feb 9].

10 Aizaz, M., Haq, I., Zahir, F., & Ullah, H. (2020). Vital Role of Medicinal Plant and Vitamin D in the

(9)

1854 http://annalsofrscb.ro

Treatment of Covid19 and other infectious diseases. GSJ, 8(7).

11 Rostami A, Sepidarkish M, Leeflang MMG, et al. SARS-CoV-2 seroprevalence worldwide:

a systematic review and meta-analysis [Internet]. Elsevier B.V. Clin Microbiol Infect. 2020.

https://doi.org/10.1016/j.cmi.2020.10.020 [cited 2021 Feb 12]. Available from:, Vol. 0 12 Brant-Zawadzki M, Fridman D, Robinson PA, et al. SARS-CoV-2 antibody prevalence in

health care workers: preliminary report of a single center study. PloS One. 2020;15 (11), e0240006. https://doi.org/10.1371/journal.pone.0240006.

13 Shields A, Faustini SE, Perez-Toledo M, et al. SARS-CoV-2 seroprevalence and asymptomatic viral carriage in healthcare workers: a cross-sectional study. Thorax. 2020;75:1089–1094.

14 Zahir, F., Haq, I., Haq, M., Khan, A. S., Naushad, W., Rajab, H., ... & Munir, I. (2021).

Epidemiological characteristics and genetic diversity of clinically isolated dengue vector in Khyber Pakhtunkhwa, Pakistan. Clinical Epidemiology and Global Health, 12, 100863.

15 Anwar, F. (2020). Serological and Epidemiological Evaluation of active HCV Infection in the Volunteer blood Donor at District Swat Khyber Pakhtunkhwa Pakistan. Bull. Env. Pharmacol. Life Sci, 9, 08-15.

16 von Hippel PT. Mean, median, and skew: correcting a textbook rule [cited 2021 Feb 12] J Stat Educ [Internet]. 2005 Jan;13(2). Available from https://www.tandfonline.

com/doi/full/10.1080/10691898.2005.11910556.

17 Wang X, Guo X, Xin Q, et al. Neutralizing Antibodies Responses to SARS-CoV-2 in COVID-19 Inpatients and Convalescent Patients [Internet]. medRxiv. medRxiv; 2020.

https://doi.org/10.1101/2020.04.15.20065623 [cited 2021 Feb 4], 2020.04.15.20065623.

Available from:.

18 Hu WT, Christina Howell J, Ozturk T, et al. Antibody Profiles According to Mild or Severe SARS-CoV-2 Infection [Internet]vol. 26. Atlanta, Georgia, USA: Emerging Infectious Diseases. Centers for Disease Control and Prevention (CDC); 2020. https://

pubmed.ncbi.nlm.nih.gov/32857691/, 2020 [cited 2021 Feb 4]. pp. 2974–8. Available from:.

19 Cervia C, Nilsson J, Zurbuchen Y, et al. Systemic and mucosal antibody responses specific to SARS-CoV-2 during mild versus severe COVID-19. J Allergy Clin Immunol. 2021 Feb 1;147(2):545–557.e9.

20 Nikolai LA, Meyer CG, Kremsner PG, Velavan TP. Asymptomatic SARS coronavirus 2 infection: invisible yet invincible [internet]. Elsevier B.V. Int J Infect Dis. 2020;100.

https://doi.org/10.1016/j.ijid.2020.08.076 [cited 2021 Feb 10], 112–6. Available from 21 Wellinghausen N, Plonn´e D, Voss M, Ivanova R, Frodl R, Deininger S. SARS-CoV-2- IgG

response is different in COVID-19 outpatients and asymptomatic contact persons [cited 2021 Feb 10] J Clin Virol [Internet]. 2020 Sep 1;130:104542. Available from https://pubmed.ncbi.nlm.nih.gov/32707511/.

22 Tripathi S, Deshmukh V, Patil A, Tipathi JP. COVID 19 diagnostic multiplicity and its role in community surveillance and control [Internet] [cited 2021 Feb 4] Infezioni Med Le;

2020:18–28. Available from: https://pubmed.ncbi.nlm.nih.gov/32532934/.

23 Amanat F, Stadlbauer D, Strohmeier S, et al. A serological assay to detect SARS-CoV-2 seroconversion in humans [cited 2021 Feb 10] Nat Med [Internet]. 2020 Jul 1;26 (7).

https://doi.org/10.1038/s41591-020-0913-5. Available from, 1033–6.

24 Sethuraman N, Jeremiah SS, Ryo A. Interpreting diagnostic tests for SARS-CoV-2 [internet]

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[cited 2021 Feb 10] JAMA - Journal of the American Medical Association. American Medical Association. 2020;323. Available from https://jamanetwork.com/, 2249–51.

25 Rosado J, Pelleau S, Cockram C, et al. Serological Signatures of SARS-CoV-2 Infection:

Implications for Antibody-Based Diagnostics [Internet]. medRxiv. medRxiv; 2020.

https://doi.org/10.1101/2020.05.07.20093963 [cited 2021 Feb 10]. p. 2020.05.07.20093963, Available from:.

26 Seow J, Graham C, Merrick B, et al. Longitudinal observation and decline of neutralizing antibody responses in the three months following SARS-CoV-2 infection in humans.

Available from Nat Microbiol [Internet]. 2020 Dec 1;5(12):1598–1607.

https://doi.org/10.1038/s41564-020-00813-8 [cited 2021 Feb 10].

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