https://orcid.org/0000-0003-2187-8894
Figures
Abstract
Background
Frontline healthcare workers (HCWs) are among the first professionals significantly impacted by epidemics and pandemics. During the COVID-19 pandemic, HCWs had an increased risk of infection. This study aimed to determine the seroprevalence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) among Nigerian HCWs.
Methods
A cross-sectional study of 1,247 randomly selected HCWs, was conducted across seven healthcare facilities in Nigeria, from August 2022 through December 2022 (Epi week 31−51). This study had two parts: the knowledge, attitude, and practices (KAP) survey and the seroprevalence of SARS-CoV-2 antibodies. Healthcare cadres enrolled were nurses, laboratorians, doctors, and pharmacists who provided informed consent before enrollment. An antigen-based COVID-19 rapid diagnostic test was used to screen all HCWs at enrollment, and a SARS-CoV-2 Multi-Antigen IgG assay was used to test for the presence of SARS-CoV-2 antibodies for the seroprevalence component of the study.
Findings
A total of 1,247 HCWs were enrolled 682 (54.6%) nurses, 286 (22.9%) laboratorians, 222(18.0%) doctors, and 57(4.5%) pharmacists. The majority HCWs were males (70.5%), lived in urban areas (90.2%), had tertiary education (64.0%), and were married (81.7%). The proportion of HCWs that used drugs or smoked was 0.2%. The seropositivity of SARS-CoV-2 amongst HCWs was 98.2% of which 80.6% where due to the Nucleocapsid protein and 17.6% due to the Spike protein. Nurses were three times more likely to be seropositive for COVID-19 than laboratorians (P < 0.05).
Interpretation
Our findings reveal a high prevalence of SARS-CoV-2 antibodies among HCWs, especially among nurses. At the time of this study, half of the HCWs were unvaccinated for COVID-19. As frontline HCWs remain at increased risk of occupational exposure, this study highlights the need to strengthen infection prevention strategies, particularly vaccination and infection prevention and control measures, to protect the healthcare workforce.
Citation: Iriemenam NC, Osawe S, Akanbi OA, Akinmulero O, Abubakar AG, Okoli M, et al. (2026) High prevalence of SARS-CoV-2 antibodies among frontline healthcare workers during the COVID-19 pandemic in three states of Nigeria from August to December 2022. PLoS One 21(8): e0354606. https://doi.org/10.1371/journal.pone.0354606
Editor: Anete Trajman, Federal University of Rio de Janeiro, BRAZIL
Received: October 14, 2024; Accepted: July 8, 2026; Published: August 10, 2026
This is an open access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication.
Data Availability: The data for this project are in custody of the government of Nigeria [Nigeria Centre for disease control and prevention (NCDC)] https://ncdc.gov.ng/ncdc.gov.ng/ and can be made available upon request to the Director General of NCDC. The NCDC can be contacted at info@ncdc.gov.ng.
Funding: U.S. Centers for Disease Control and Prevention (CDC) under cooperative agreement Strengthening Global Health Security Agenda in Nigeria NU2HGH000020-01-00.
Competing interests: The authors have declared that no competing interests exist.
Introduction
The coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), had a profound impact on global health and well-being, overwhelming healthcare systems and disrupting the delivery of essential health services worldwide. [1]. A socio-economic analysis in Nigeria reported that the COVID-19 pandemic affected the healthcare system and many socio-economic activities, resulting in an economic downturn [2]. The pandemic had a particularly huge impact on routine healthcare services as resources were redirected to control the surge of the virus across the population. As a result, management and care for other diseases were negatively impacted leading to delays in treatment and poor delivery of quality healthcare services [3]. The COVID-19 pandemic highlighted the need to ensure adaptable health systems that can absorb the demands in managing disease outbreaks while protecting the health and wellbeing of the healthcare workforce.
Healthcare workers (HCWs) are at the forefront of public health emergency response, providing care for the earliest cases of emerging infectious diseases. This frontline role places them at a significantly increased risk of occupational exposure to infectious pathogens. [4]. The United States Centers for Disease Control and Prevention (U.S. CDC) reported that 315,531 COVID-19 cases were reported between February and April 2020 in the United States of which 49,370 included information on whether patients were HCWs and 19% of these cases were HCWs [5]. With the high risk of COVID-19 infections among HCWs, tools were adopted to assess risk factors for the disease [6–8]. The knowledge, attitudes, and practices (KAP) model was adopted to collect information about HCWs [8]. KAP scores inform behaviors and measure the understanding and adherence to safety precautions among HCWs during pandemics like COVID-19. Although numerous studies have been conducted on the KAP of COVID-19 among HCWs, there is limited evidence about the relationship between KAP and the seroprevalence of COVID-19 among HCWs [9–12].
The COVID-19 vaccine protects against severe disease and has been recommended to general populations from > 6 months of age [13]. As of 26th November 2023, 13,516,282,548 COVID-19 vaccine doses were administered globally, of which 67% of the global population have been vaccinated with a complete primary series and only 32% with at least one booster dose [1]. Although COVID-19 vaccines were introduced and recommended for healthcare workers (HCWs) in Nigeria in March 2021, a study conducted between April and June 2022 found that only 44% of HCWs had received at least one dose of a COVID-19 vaccine, either partially or fully completing the vaccination schedule.[14]. Vaccine hesitancy amongst HCWs increases the risk of disease transmission within the healthcare setting and across the population.
While studies have been conducted in Nigeria and have reported a seroprevalence of SARS-CoV-2 between 9.3 and 94.0% among HCWs, most of these studies were conducted earlier, between the onset of the pandemic and 2021, or on smaller sample sizes [14–17]. Estimating SARS-CoV-2 seroprevalence among HCWs is critical for understanding the level of exposure and immunity which can be used to guide strategies to promote disease control amongst HCWs. This study aims to estimate SARS-CoV-2 seroprevalence among different cadres of HCWs during the fourth wave of COVID-19.
Methods
Study design
A multicenter cross-sectional study was conducted in seven health facilities in three Nigerian states (Plateau, Oyo, and Rivers), between August 2022 and December 2022 (Epi week 31–51). In collaboration with the U.S. CDC and the Nigerian Centre for Disease Control and Prevention (NCDC), these three states were purposively selected to represent the states that studies on seroprevalence were not conducted. Secondary and tertiary healthcare facilities were allocated sample quotas based on their pool of HCWs and according to probability proportional to size. The study utilized a state-stratified random sampling strategy to generate a line list of all HCWs at each selected health facility within the state.
Study participant
Frontline HCWs, including medical doctors, laboratorians, nurses, and pharmacists from the selected healthcare facilities, were randomly selected to participate in the study. Using a randomized line list of HCWs, every fourth name was consecutively invited to participate in the study. Invitations were sent via text messages and phone calls to the selected HCWs. Using a precision-based approach, the sample size estimation was 1,247 HCWs assuming a seroprevalence of 15%, 95% confidence level, precision level of ±3%, design effect of 1.5, projected 30% non-response rate, medium effect size of 10%, statistical power of 80% and a type 1 error rate of 5% for the comparison of prevalence estimates across the cadres of HCWs. A structured self-administered questionnaire designed on the Research Electronic Data Capture (REDCap) application was used to collect information on KAP to COVID-19, socio-demographic, epidemiological information (exposure, clinical and health-related characteristics) and COVID-19 vaccination data, from each participant.
Procedure
Five milliliters of venous blood were collected in EDTA tubes at designated phlebotomy sections by trained phlebotomists and transported to the processing laboratories in cold chain (2-8oC), at each selected health facility Whole blood samples were processed into plasma within four hours of sample collection, by centrifugation at 2,200−2,500 resolutions per minute for 20 minutes.. The plasma samples were separated, aliquoted into two 1 milliliter cryovials, and stored in a -20oC freezer until transported to the National Reference Laboratory (NRL) for testing. Shipments were temperature-controlled using Credo Cubes (M50 series) shipping container, through an authorized local courier provider. Additionally, nasopharyngeal swabs were collected for antigen-based rapid diagnostic test (RDT) COVID-19 testing (SD Biosensor COVID-19 Rapid Antigen Test Kit), following the manufacturer’s instructions [18]. Participants who tested positive by the SARS-CoV-2 rapid antigen test were referred for confirmatory testing using reverse transcription polymerase chain reaction (RT-PCR). [19].
SARS-CoV-2 Multi-Antigen IgG Bead Assay (SARS2MBA)
The SARS2MBA developed by the U.S. CDC was validated in Nigeria before use and described in previous studies [20,21]. Briefly, plasma samples were diluted to 1:400 in Buffer B (1X phosphate-buffered saline [PBS], 0.5% casein, 0.5% polyvinyl alcohol [PVA], 0.8% polyvinylpyrrolidone [PVP], 0.3% Tween-20, 0.02% sodium azide (NaN3) and 3 µg/ml Escherichia coli extract). The diluted sample (50 µl) was incubated with beads (1250 µl/well/antigen) in a 96-well flat bottom (Bio-Plex assay) plate for 1.5 hours. The beads were washed three times with 200 µl phosphate-buffered saline solution (PBST) (1X PBS + 0.05% Tween-20) using a magnetic 96-well separator (Thermofisher) to hold the beads to the plate while the liquid was decanted. They were incubated with 50 ng IgG (Southern Biotech, Birmingham, AL) and 20 ng IgG4 (Southern Biotech) to detect bound antibodies for 45 minutes, after which they were washed three times with PBST and incubated with 250 ng SAPE (Invitrogen, San Francisco, CA) for 30 minutes. The beads were washed three times with PBST and incubated with 1X PBS, 0.5% bovine serum albumin (BSA), 0.05% Tween-20, and 0.02% NaN3 for 30 minutes to remove any loosely bound antibodies. The beads were rewashed, suspended in 1X PBS, and stored overnight at 4°C. The next day, the beads were read on a Luminex MAGPIX® instrument with the average median fluorescence intensity (MFI) determined for each sample and seropositivity to SARS-CoV-2 antibodies decided if samples tested positive for the spike glycoprotein (S) and receptor-binding domain 591 (RBD591) within the spike glycoprotein.
Result interpretation for SARS-CoV-2 seropositivity
Antibodies against SARS-CoV-2 were previously established based on the validated U.S. CDC-established MFI cut-off values: S (125), RBD591 (971), and N proteins (1199), respectively. SARS-CoV-2 seropositivity was based on set median fluorescence intensity (MFI) cut off values for S, RBD591 and N proteins. Samples were reported as seronegative for SARS-CoV-2 if both S and RBD591 had cut-off MFI values were below the positivity threshold (S-/RBD591+ or S + /RBD591-), irrespective of the N values (N + /N-). SARS-CoV-2 seropositivity was defined as IgG antibody positive for both S and N proteins (S + N+). Additionally, current SARS-CoV-2 seropositivity was defined as a combination of S + /RBD591 + /N + . However, antibody positivity to S and RBD591 protein and negative to N protein could have four different interpretations: [1] the participants were vaccinated, [2] the participants with no natural infection or a natural infection with waning N antibodies, [3] the clients have antibodies from SARS-CoV-2 infection and failed to develop detectable N antibodies, or [4] a combination of antibodies from SARS-CoV-2 infection and vaccination (hybrid immunity).
Study instrument
A structured interviewer administered questionnaire was used to assess the knowledge, attitude, and practice (KAP) of HCWs towards COVID-19. The knowledge section had 24 questions assessing the awareness of the etiology, symptoms, transmission, prevention, control and management of COVID-19. Attitude section included nine questions assessing perceptions of HCWs about infection prevention and control (IPC), management of cases, mitigating strategies, and incentives in a 5 points Likert scale, and a 3 points scale for only two questions. The practice section included six questions assessing the use of personal protective equipment, adherence to IPC, individual treatment of flu-like symptoms in a 7 points scale, and 4 points scale for only one question. Good KAP towards COVID-19 was derived from the total score over the total obtainable score for each KAP multiplied by 100 (S1 Form).
Study variables
The primary outcome for this study was seropositivity of SARS-CoV-2 among HCWs. The characteristics of HCWs were further grouped into five sections, including the socio-demographic characteristics, household and facility information, exposure, clinical and health-related information, and lifestyle factors among the study participants. Exposure characteristics assessed include COVID-19 testing history, vaccination, self-reported diagnosis, and symptoms, exposure, travel history. Lifestyle characteristics like body mass index (BMI), smoking, alcohol, drug use, knowledge, attitude, and practices towards COVID-19 prevention and control were also evaluated. Occupational exposure was defined as contact with positive patients or infected sample. Also, good knowledge, attitude, and practice (KAP) towards COVID-19 was defined by ≥80% score to the KAP questions.
Statistical analysis
Data from RedCap was exported to Microsoft Excel version 365 for data cleaning and coding. Cleaned and coded data was then imported into the statistical software STATA (version 18) for statistical analysis. Descriptive analysis was presented in frequencies (percentages) for all the categorical variables and the mean (standard deviation) or equivalent median (interquartile range) for continuous variables. Normality was assessed via the Shapiro-Wilk test for anthropometric data (body mass index), and a graphical presentation (histogram) was reported. Socio-demographic characteristics, household and facility information, exposure, clinical and health-related information, and lifestyle factors were five classes of explanatory variables built-in models of five blocks, with each class constituting a block to identify factors associated with the seropositivity rate (due to current, previous and all infection) in a stepwise model selection approach. The block of model selection was performed based on the variable importance due to the significant change in the model likelihood ruled at p < 0.20 at the univariate level.
The 3-series of multivariable model analysis was conducted via the log-binomial model to evaluate the adjusted variable effect on the 3-distinct seropositivity outcome, respectively, and the variables identified from the five model blocks made up the predictors. The model block that minimizes information loss was determined from the minimum Akaike information criterion (AIC) statistics. The level of association and significance of the SARS-CoV-2 IgG positivity with the identified predictors was assessed, and the corresponding adjusted and crude risk ratio and the 95% confidence interval were reported at a 5% alpha significance level.
Ethical statement
Ethical approvals were received from the National Health Research Ethics Committee (NHREC/01/01/2007) and the institutional ethical committees at each healthcare facility. This activity was reviewed by the U.S. CDC and deemed not research. It was conducted consistent with applicable federal law and U.S. CDC policy.§. U.S. CDC staff did not contact participants nor access personal identifying information. Prior to sample collection, eligible HCWs in selected healthcare facilities were verbally recruited to participate in the survey. Interested HCWs were provided with adequate information on the study objectives, procedure and potential risk from participating in the study and were expected to sign an informed consent form. Participants that signed the informed consent form were included and data was deidentified to protect the confidentiality of the study participants. Also, participation in the study was completely voluntary and participants were allowed to withdraw from the study at any period they felt uncomfortable.
§ See, e.g., 45 C.F.R. part 46.102(l) [2], 21 C.F.R. part 56; 42 U.S.C. §241(d); 5 U.S.C. §552a; 44 U.S.C. §3501 et seq.
Results
Descriptive statistics of HCWs in the three Nigerian States
A total of 1,247 HCWs were enrolled, with 682 (54.6%) nurses and 56 (4.5%) pharmacists which were the least represented HCW group. The majority of the Majority of the doctors (65.8%) and pharmacists (60.7%) were female while nurses (90%) and laboratorians (60.7%) were male in majority. A total of 580 (46.6%) healthcare workers (HCWs) reported occupational exposure to COVID-19. Additionally, 40.9% had contact with suspected COVID-19 cases, while 36.8% reported contact with confirmed cases. Only 26 (2.1%) HCWs reported living with an individual suspected of having COVID-19.. Only 323 (26%) of the HCWs self-reported that they experienced symptoms of COVID-19, and 187 (15%) were previously diagnosed with COVID-19 infection. As part of the project, HCWs were tested for a current COVID-19 infection using RDT, and six (0.5%) tested positive (Table 1). Although the majority of the HCWs reported good knowledge (64.7%) and attitude (51.3%) about COVID-19 prevention and control measures, only 66 (5.3%) had good practices regarding COVID-19 infection prevention and control protocols. Laboratorians made up the highest proportion of HCWs with poor knowledge (40.9%), attitude (54.2%), and practice (97.9%) regarding COVID-19 prevention and control measures (Table 1).
SARS-CoV-2 IgG seropositivity by cadre of HCWs in Three Nigerian States
The SARS-CoV-2 seropositivity to S protein was 17.6% (95%CI = 15.5%−19.8%), while SARS-CoV-2 seropositivity to N protein was 80.6% (95%CI = 78.3%−82.6%). The overall SARS-CoV-2 seroprevalence [S + /RBD591 + /N+(N-)] of the HCWs in this study was 98.2%. (95%CI = 97.3%−98.8%), while SARS-CoV-2 seronegative prevalence (S-/RBD591-/N-) was only 1.8% (95%CI = 1.1%−2.7%) (Fig 1).
While SARS-CoV-2 seropositivity was high among all HCW cadres and across all the states, it was slightly lower among in Plateau State (95.8%) compared to those in Rivers (99.7%) and Oyo (99.3%) states (p < 0.001). SARS-CoV-2 seropositivity was slightly higher among vaccinated HCWs (98.6%) and HCWs with travel history to COVID-19-affected areas (98.3%). SARS-CoV-2 seropositivity was lower among HCWs that tested Ag-RBD positive during enrollment (p = 0.007), slightly higher among those with satisfactory knowledge (98.6%) than those with unsatisfactory knowledge (97.5%) (S2 Table).
Reported COVID-19 symptoms by cadre of HCWs in Three Nigerian States
Among healthcare workers (HCWs) who reported symptoms suggestive of COVID-19, the most frequently reported symptoms were body aches and pains (66.9%), tiredness (65.6%), nasal congestion (63.5%), and dry cough (60.0%). Fever was reported by 52.0% (n = 168) of symptomatic HCWs and was most common among doctors (72.0%) and pharmacists (70.0%). Additionally, loss of smell and loss of taste were reported by 40.0% and 37.8% of HCWs, respectively (S1 Table).
Bivariate analysis of factors associated with SARS-CoV-2 IgG seropositivity among HCWs in Three Nigerian States
Table 2 shows the demographics, facility, exposure, clinical, and lifestyle factors associated with SARS-CoV-2 IgG seropositivity among HCWs at p < 0.20. HCW’s facility of practice was associated with N seropositivity (LR-X2 = 32.7, p < 0.001). HCW’s years of practice (LR-X2 = 4.43, p = 0.035), occupational exposure (LR-X2 = 4.13, p = 0.042), living with a person suspected with COVID-19 infection (LR-X2 = 4.55, p = 0.032) and previous COVID-19 test by RDT (LR-X2 = 5.61, p = 0.018) were associated with SARS-CoV-2 IgG seropositivity to S protein. Age, facility ownership, being tested for COVID-19 were associated antibody seropositivity to S + /RBD591 + /N- (p < 0.10). Also, household type and size, cadre of HCWs, blood group, and HCW on medication as well as obesity status were associated with SARS-CoV-2 IgG seropositivity based on S+ (p < 0.20). Similar factors were associated with SARS-CoV-2 IgG seropositivity N protein. Facility of practice (LR-X2 = 14.16, p = 0.002), occupational exposure (LR-X2 = 4.20, p = 0.040), previous COVID-19 test by RDT (LR-X2 = 5.48, p = 0.019), and drug use (LR-X2 = 5.00, p:.025) were associated with SARS-CoV-2 IgG seropositivity based on N+ (p < 0.05). Other factors, including education, frequency of time spent away from work due to COVID-19, and knowledge of COVID-19, were associated with SARS-CoV-2 IgG seropositivity to the N protein p < 0.20 (Table 2).
Multivariate logistic regression analysis of factors associated with SAR-CoV-2 IgG seropositivity among HCWs in Three Nigerian States
The multivariable logistic regression explored in model blocks for each SARS-CoV-2 IgG seropositive natural (previous/current), and all infection versus seronegative is presented in Table 3. HCWs that were occupationally exposed to SARS-CoV-2 had a 96% lower risk of seropositivity from previous infection compared to their occupationally unexposed counterpart (aRR = 0.04, 95%CI = 0.004–0.58). Nurses were more likely to be seropositive due to natural infection than laboratorians (aRR = 386.33, 95%CI= (9.34–15978.8). Odds of seropositivity were reduced by 93% in HCWs with the A blood group compared to the O blood group. The likelihood of seropositivity due to previous infection was significantly higher among HCWs practicing at University of Port Harcourt Teaching Hospital (UPTH) compared to BUTH (aRR = 442.47, 95%CI = 3.59–54434.99, p < .05). The odds of SARS-CoV-2 IgG seropositivity due to previous infection were also higher among HCWs with 6–10 years working experience compared to those with >15 years’ experience. HCWs within age-group of 51–60 years compared to those in age-group 21–30 years had higher odds of SARS-CoV-2 IgG seropositivity. After adjusting for other factors, nurses’ odds of SARS-CoV-2 IgG seropositivity were three times higher than laboratorians (aRR = 3.02, 95%CI = 1.10–9.05) (Table 3).
Discussion
In this study, we assessed the seroprevalence of SARS-CoV-2 among healthcare workers (HCWs) across multiple health facilities and observed a high prevalence of SARS-CoV-2 IgG antibodies between August 2022 through December 2022. In contrast, a similar study conducted in Lagos during the early phase of the pandemic (December 2020 to July 2021) reported a lower seroprevalence of 30.9% [4]. Comparable findings were reported in another study, which documented a SARS-CoV-2 seroprevalence of 72.4% among HCWs in early 2021 [16]. Our study was conducted after the fourth pandemic wave where new variants such as delta (2021) and omicron (2022) were identified, providing more time for possible exposure among HCWs in Nigeria. Additionally, the scale up vaccination may have influenced the high seropositivity reported as approximately 50% of the HCWs were vaccinated prior to the study. This may have accounted for the higher seroprevalence of COVID-19 among HCWs. A previous study on HCWs indicated an increasing trend in SARS-CoV-2 seropositivity from 31% at baseline to 45% after three months and 70% after six months of follow-up [17].
Studies on pre-pandemic samples have been conducted in Nigeria, Gabon, and Senegal reporting data on cross-reactive humoral responses against SARS-CoV-2 S and N glycoproteins on pre-pandemic samples [22,23]. However, one of these studies used an ELISA based diagnostic method and found that these cross-reactive antibodies had no significant reduction on the SARS-CoV-2 viral load of lungs [24]. A previous study showed higher recognition of human coronaviruses in Tanzania and Zambia pre-pandemic samples than in the U.S [24]. These may suggest pre-existing humoral immunity distinct to sub-Saharan African populations. Another study from Mali in 2021 showed high SARS-CoV-2 seropositivity (61.8%) amongst frontline HCWs [25] and in a systematic review reported high SARS-CoV-2 seroprevalence in the African population, suggestive of high exposure to the virus and a potential for population immunity and lesser risk for severe diseases [26]. Our study adopted several multivariate logistic regression analyses in five model blocks. In model blocks IV and V, nurses were more likely to be seropositive for COVID-19 than laboratorians. Our findings are similar to those of other studies in the U.S. and Egypt that reported higher odds of COVID-19 seropositivity among nurses, with doctors as the reference cadre [27,28]. Nurses may have higher occupational exposure to COVID-19 infected patients with longer contact times during care and treatment making them have an increased risk of exposure and infection within the cadre compared to other HCWs.
We assessed the association between knowledge, attitudes, and practices (KAP) and SARS-CoV-2 seroprevalence, which, to the best of our knowledge, is the first such analysis conducted in a Nigerian population. A study conducted across eleven Nigerian states found that community healthcare workers (HCWs) demonstrated high levels of KAP, as well as a strong capacity to provide health education and promote adherence to national COVID-19 guidelines. [29]. Although most HCWs demonstrated good knowledge of COVID-19, this did not translate into appropriate IPC practices. Similar finding were reported by Harun et al [30]. These findings underscore the need for interventions that not only improve knowledge but also strengthen adherence to infection prevention and control measures and promote behavior change among healthcare workers [31]. Overall, our findings indicate that workplace-related factors, particularly occupational exposure and healthcare facility of practice, were the strongest correlates of SARS-CoV-2 seropositivity among healthcare workers. Strengthening IPC programmes in clinical sites, ensuring consistent access to appropriate personal protective equipment, and implementing facility-specific risk mitigation strategies remain critical.
A recent study following vaccination trends in the U.S. shows that COVID-19 vaccination reduced COVID-19-related cases and hospitalizations [32]. Vaccination is the most effective public health intervention and the cornerstone of the most cost-effective healthcare interventions, and addressing vaccine hesitancy is crucial to lessen the negative consequences of the COVID-19 [33,34]. Despite the availability of COVID-19 vaccines, vaccination coverage among HCWs in our study remained suboptimal. Previous studies in Nigeria have identified educational level, occupation, religion, and prior COVID-19 diagnosis as key determinants of vaccine uptake. [35].
We had some limitations in our study. The study was conducted in three states of the country which may not be representative of all HCWs in Nigeria. The study population was predominantly composed of experienced healthcare workers employed in urban public health facilities. The high COVID-19 seropositivity of HCWs may have introduced bias in the comparison between groups, either by masking variation in disease exposure or the level of immunity. We also did not differentiate seropositivity due to natural infection or COVID-19 vaccination. The scale-up of COVID-19 vaccines amongst HCWs and across the population may have also accounted for the higher seropositivity rate, as they were the first group to be vaccinated in Nigeria. We also do not have data on full or partial COVID-19 vaccinations received by HCWs in our study which limited our ability to determine if the detection of antibodies was due to natural infection or vaccination. However, this is a multi-state study and provides data on a larger proportion of HCWs compared to other studies conducted in one state. We are also the first to assess factors responsible for COVID-19 infection among HCWs using five model blocks. Thus, the statistical model incorporated in this study accurately assesses the factors responsible for SARS-CoV-2 seropositivity while considering potential confounding variables.
Our analysis indicates that HCWs’ attitudes and practices towards COVID-19 were relatively poor, and KAP was not associated with COVID-19 infection. Given the role of KAP in lowering the risk of infectious diseases, interventions towards enhancing HCWs’ attitude and practices of HCWs to infectious diseases and prevention strategies may be beneficial in ensuring disease prevention and control measures during disease outbreaks and pandemics. Also, interventions like infection control training, supply of personal protective equipment and surveillance testing are important in mitigating the risk of the seropositivity amongst high-risk groups.
Supporting information
S1 File. Questionnaire for Knowledge Attitudes and Practices of COVID-19 among Healthcare Workers in Nigeria.
https://doi.org/10.1371/journal.pone.0354606.s001
(PDF)
S1 Table. Self-reported Symptoms by Cadre HCWs.
https://doi.org/10.1371/journal.pone.0354606.s002
(PDF)
Acknowledgments
We thank all the HCWs who participated in this study. We also appreciate the support from the state government health sector leadership in the three states we implemented this project (Oyo, Plateau, and Rivers) and seven facilities (Rivers State University Teaching Hospital, University of Port-Harcourt Teaching Hospital, Plateau State Teaching Hospital, Jos University Teaching Hospital, Bingham University Teaching Hospital, University College Hospital Ibadan, Ladoke Akintola University Teaching Hospital Ogbomosho) that participated in this study. The authors also thank the Multiplex Bead Assay and Biorepository Teams at the National Reference Laboratory of the Nigeria Centre for Disease Control and Prevention for their professional assistance in this project. We also thank members of the SECURE Nigeria Project Team (Andrew Thomas, Timothy Attah, Samson Babatunde Adebayo, Temitope Olaleye, Felix Villeng, Item Inya Item, Samuel Awala, Felicia Nwatu, Loveth Akayi, Joseph Dattijo, Blessing Ugboaja, Ifeanyichukwu Udoh, Oluremi Are, Peace Samuel, Akinyemi Oyebanjo, Chinwe Ugwu, Michael Ajigo, Elonna Marylyn Obak, Elima Jedy-Agba) of the Institute of Human Virology Nigeria for their contribution to completion of this study.
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