|Year : 2016 | Volume
| Issue : 2 | Page : 79-85
A survey of knowledge and reporting practices of primary healthcare workers on adverse experiences following immunisation in alimosho local government area, Lagos
Riyike Alaba Ogunyemi1, Olumuyiwa O Odusanya2
1 Onilekere Primary Healthcare Center, Ikeja Local Government, Ikeja, Lagos, Nigeria
2 Department of Community Health and Primary Healthcare, Lagos State University College of Medicine, Ikeja, Lagos, Nigeria
|Date of Web Publication||13-Jul-2016|
Riyike Alaba Ogunyemi
Onilekere Primary Healthcare Center, Ikeja Local Government, Ikeja, Lagos
Source of Support: None, Conflict of Interest: None
Background: A descriptive cross-sectional survey was conducted among healthcare workers offering immunisation services in primary healthcare facilities in Alimosho Local Government Area, Lagos, Nigeria, on knowledge and reporting practices of healthcare workers on adverse events following immunisations (AEFIs).
Materials and Methods: A pre-tested, close-ended, self-administered questionnaire was used to assess knowledge and reporting practices on AEFI. Data were analysed using Statistical Package for Social Sciences (SPSS) version 16. Knowledge of healthcare workers was scored and graded as <50% - poor, 50–74% - fair and ≥75% - good. Reporting practices on AEFI was classified as good if it was reported within 24 h of seeing one.P= 0.05 was considered statistically significant.
Results: One hundred and sixty-four healthcare workers duly completed and returned their questionnaires. The mean age was 39.5 ± 2.64 years and mean post-qualification experience was 12.2 ± 2.33 years. Over 80% of the healthcare workers knew that fever, pain, redness and swelling at injection site were clinical signs and symptoms of AEFI, and 93% knew about filling an adverse event form to report an AEFI. Overall, nearly 80% of respondents had fair/good knowledge on AEFI. Fifty-five (33.5%) healthcare workers had encountered an AEFI and 31 (56.4%) reported such within 24 h. There was a significant relationship between being younger healthcare workers and knowledge on AEFIs (P = 0.029). No healthcare worker characteristics were significantly associated with good reporting practices on AEFI.
Conclusion: Respondents' knowledge and reporting practices on AEFI were average.
Keywords: Adverse events following immunisation, healthcare workers, knowledge, reporting practices
|How to cite this article:|
Ogunyemi RA, Odusanya OO. A survey of knowledge and reporting practices of primary healthcare workers on adverse experiences following immunisation in alimosho local government area, Lagos. Niger Postgrad Med J 2016;23:79-85
|How to cite this URL:|
Ogunyemi RA, Odusanya OO. A survey of knowledge and reporting practices of primary healthcare workers on adverse experiences following immunisation in alimosho local government area, Lagos. Niger Postgrad Med J [serial online] 2016 [cited 2019 Mar 26];23:79-85. Available from: http://www.npmj.org/text.asp?2016/23/2/79/186300
| Introduction|| |
Immunisation is the process by which a person is made immune or resistant to an infectious disease, typically by the administration of a vaccine. Immunisation is estimated to avert between 2 and 3 million deaths globally each year  and is stated by the American Center for Disease Control as one of the 'ten great public health achievements in the 20th century'. Adverse events following immunisation (AEFI) is an untoward event temporally associated with immunisation that might or might not be caused by the vaccine or the immunisation process.
AEFIs are divided into five categories: first, vaccine product-related reactions (AEFIs that are caused or precipitated by a vaccine due to one or more of the inherent properties of the vaccine product); second, vaccine quality defect-related reactions (AEFIs that are caused or precipitated by a vaccine that is due to one or more quality defects of the vaccine product including its administration device as provided by the manufacturer). The remaining categories are immunisation error-related reactions (AEFIs which occur when there is inappropriate vaccine handling, prescribing or administration); immunisation anxiety-related reactions (AEFIs arising from anxiety about the immunisation) and coincidental events (AEFIs from other factors other than the vaccine product, immunisation error or immunisation anxiety).
Under recommended conditions, vaccines should cause no adverse events and completely prevent the intended infections. However, the current technology does not allow for such perfection. In the United States of America, of every 10,000 cases of vaccination, 1.14 cases of AEFIs were reported and deaths accounted for 1.4% of such AEFIs. In Zhejiang province of China, the overall reporting rate of AEFI was 9.2 per 100,000 doses of vaccination, and in Australia, 14.1 cases of AEFIs were reported per 100,000 doses in 2009, 129.5 per 100,000 vaccine doses in Sri Lanka as at 2012, and 19.3% in a tertiary hospital in Ilorin, Kwara State, Nigeria, in 2005. In that institution, the more common AEFIs were local swelling (50.9%), cellulitis (29.7%), injection abscesses (19.3%) and were reported more with diphtheria, pertussis and tetanus vaccine. A study of occurrence of AEFIs among children of mothers in Port-Harcourt, Rivers State, Nigeria, reported that up to 57% admitted to having at least one or more AEFIs in their children following administration of the pentavalent vaccine. The main adverse experiences were fever (88%), swelling (34%) and irritability (40%).
The clinical spectrum of AEFI is wide with fever being the most frequently reported 'serious' and 'non-serious' AEFI for all age groups. Fever was the most commonly reported general adverse event among Nigerian infants who received the 10-valent pneumococcal non-typeable Haemophilus influenzae protein D conjugate vaccine. In Sri Lanka, the AEFI reporting rate for the pentavalent vaccine was 296.8 per 100,000 doses administered in 2012. High fever, allergic reactions, nodules, severe local reactions, seizures and injection site abscesses were the leading AEFIs reported in one study. Also on the clinical spectrum of AEFI is anaphylaxis – an acute hypersensitivity reaction with multi-organ systemic involvement that may rapidly progress to a life threatening reaction. Although rare, with an incidence rate of 0.65 cases per million doses of vaccine, anaphylaxis is a well-known AEFI that may occur following immunisation without a prior warning.
Even though AEFIs are well-known, not much is known about how healthcare workers recognise or report them. Reporting AEFIs is important in recognising the occurrence of rare events for new vaccines which may not be known during clinical trials or to monitor the rates of such events for well-established vaccines. Poor knowledge of AEFI among healthcare workers will result in many cases of AEFI going unreported and unaddressed, which may undermine confidence in national immunisation programmes, as well as reduce immunisation uptake and have a negative public health impact. A study examining Canadian family physicians awareness of vaccine-associated adverse events showed that less than half of the study respondents were aware of a monitoring system for AEFI, one-third knew of the reporting criteria and only one in four had received vaccine adverse events education during medical training. A study in the United States of America among physicians, pharmacists and nurses that examined reporting systems, the frequency of reporting of vaccine adverse events, beliefs and awareness of AEFI found that 71% had never reported AEFI, and 17% indicated they were not aware of how to report. A study from the United Kingdom on AEFI reporting of meningococcal serogroup C conjugate vaccine found that nurses reported AEFIs more frequently than general practitioners and hospital doctors.
Among mothers in Awe Local Government Area (LGA) of Kwara State, Nigeria, concerns about safety of vaccines were major reasons for non-completion of immunisation. It would then seem that adverse experiences may be a limiting factor to full uptake of vaccines. However, this was not so in Enugu among about 80% of mothers who would not allow adverse experiences deter them from immunizing their children. Immunisation services are received by the majority of children at primary healthcare facilities, and knowing that AEFIs may occur is important and, therefore, should be known and reported by the healthcare workers administering vaccines at these facilities. Thus, the objective of this study was to determine the knowledge and reporting practices of healthcare workers on AEFI in primary healthcare facilities in Alimosho LGA.
| Materials and Methods|| |
Alimosho LGA is a densely populated suburb of Lagos State with a population of 1,288,714 as at the 2006 national census. It is one of the 57 LGAs/Local Council Development Areas (LCDAs) in Lagos. Alimosho is a semi-rural area and one of the largest LGAs in Lagos. It is divided into six administrative zones: Alimosho Local Government, Agbado-Okeodo LCDA, Ayobo-Ipaja LCDA, Egbe-Idimu LCDA, Ikotun-Igando LCDA and Mosan-Okunola LCDA. The people of Alimosho enjoy a rich supply of healthcare services from both private and government providers. The government-owned health facilities include the Alimosho General Hospital, Igando, and the 29 primary healthcare centres which are located within the six administrative zones of the LGA. There were 214 health workers offering clinical services at the primary healthcare centres in the LGA.
Sample size determination and selection of participants
The minimum sample size for the study (n = 178) was determined using Fisher's formula, with standard normal deviation at 95% confidence interval (1.96), prevalence rate of 0.71 (proportion of healthcare workers who were aware of the reporting system for AEFIs) and precision of ± 7% (0.07). However, only healthcare workers directly involved with vaccination and management of AEFI were eligible. Non-consenting staff involved in vaccination were excluded. All eligible (n = 176) healthcare workers were included in the study.
Study instrument, data collection and analysis
A self-administered, close-ended questionnaire was developed for this study from a review of literature. The instrument enquired on demographic details, knowledge of healthcare workers on signs and symptoms of AEFI, reportable AEFIs and methods of reporting AEFI. It also took to cognizance trainings on AEFI that healthcare workers might have received. Furthermore, the healthcare workers were asked about encounters with AEFIs and their reporting practices. Perceived barriers to reporting AEFI were also sought for. The questionnaire was pre-tested among 53 (30% of the intended sample size) healthcare workers at Orile Agege LGA. The pre-test was carried out to fine-tune the study instrument and to remove ambiguities in the phraseology. Face validity of the instrument was done by the study supervisor through repeated checking of the instrument with relevant literature to ensure that it could achieve the objectives of the study. The reliability of the instrument was determined using the Cronbach's coefficient alpha which was 0.7.
The questionnaires were distributed to the eligible healthcare workers after immunisation clinic sessions at each health facility over a 2-week period in February 2015, and were collected as soon as the questionnaires were filled. The duly completed questionnaires were analysed using the Statistical Package for the Social Sciences (SPSS Inc., Chicago, IL) software, version 16. Descriptive statistics was computed to generate frequencies, means and standard deviations. The knowledge of the healthcare workers was determined using a total of 34 questions; each correct answer was scored one mark giving a maximum score of 34. Scores of 75% and greater (26–34 marks) were graded as good knowledge, scores between 50% and 74% (17–25) were graded as fair knowledge and scores below 50% (0–16) were graded as poor knowledge. Reporting practices on AEFI was classified as good if it was reported within 24 h of seeing one. Statistical significance was asset at P ≤ 0.05. Chi-square test was used to measure the association between dependent variables (knowledge and reporting practices on AEFI) and independent variables (demographic data of healthcare workers and training on AEFI).
A letter of introduction was obtained from the Department of Community Health and Primary Health Care of the Lagos State University College of Medicine, Ikeja for the Medical Officer of Health of Alimosho LGA. The Medical Officer of Health of Alimosho LGA granted permission for the conduct of the study. Each eligible healthcare worker was approached to inform him/her about the study objectives and written informed consent was obtained before recruitment into the study.
| Results|| |
A total of 176 questionnaires were distributed, of which 164 were duly completed, retrieved and analysed, giving a response rate of 93.2%. [Table 1] shows the sociodemographic characteristic of the healthcare workers. The mean age was 39.5 ± 2.64 years, the largest age group was 30–39 years and most (88.4%) were females. Nurses were the largest group (47%) of healthcare workers. The mean post-qualification experience was 12.2 ± 2.33 years, and most (54.2%) of the respondents had post-qualification working experience of 0–9 years.
|Table 1: Sociodemographic variables of healthcare workers in Alimosho Local Government Area|
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Knowledge of various aspects of AEFI is shown in [Table 2]. The most common AEFI symptoms identified by the respondents were fever (84.8%), redness (82.9%), swelling at injection site (89.6%) and pain (83.5%). Less than half of the respondents were familiar with encephalopathy/encephalitis, hypotonic-hyperresponsive episodes and convulsion/seizure as symptoms of AEFI. More than two-thirds of the respondents knew correctly that all cases of immunisation-related hospitalisations (69.5%), immunisation-related unusual medical incidents (69.5%) and immunisation-related deaths (67.1%) were reportable AEFIs. Over half (57.9%) of the respondents were also aware that low-grade fever (<38°C) was not a reportable AEFI. Two-thirds (68.9%) of the respondents, however, wrongly acknowledged that redness around injection site was a reportable AEFI. Most of the respondents (92.7%) knew about filling an adverse event form as a method of reporting AEFI, as well as reporting through telephone calls (65.2%). Over half of the respondents (56.1%), however, knew talking about AEFI with colleagues was not a method of reporting AEFI.
|Table 2: Knowledge of various aspects of adverse events following immunisation among healthcare workers in Alimosho Local Government Area|
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The relationship between some characteristics of the healthcare workers and knowledge score on AEFI is shown in [Table 3]. One hundred and thirty-one (79.90%) healthcare workers obtained more than 50% of the marks on knowledge of AEFIs and were classified as having either fair (55.5%) or good (24.3%) knowledge. Younger age of healthcare workers was found to have a significant relationship (P = 0.029) with knowledge. Gender, post-qualification experience and the cadre of the healthcare worker (doctor vs. non-doctor) did not have significant relationship (P > 0.05) with knowledge. When the knowledge scores were dichotomised into poor and fair/good knowledge, previous training received by health workers was not found to be significant with knowledge (Fisher's exact test, P = 0.175).
|Table 3: Health worker's characteristics and knowledge score on adverse events following immunisation in Alimosho Local Government Area|
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About one-third of the respondents had encountered AEFI in their practice. The AEFIs encountered were fever, pain, swelling which constituted minor reactions (40%); screaming and prolonged crying, abscess formation at injection site, febrile illness constituted severe adverse reactions seen (10.9%), while acute flaccid paralysis and urticarial rash were serious AEFIs (10.9%). All healthcare workers who had encountered AEFI in their practice reported (51.5%) or treated/reassured the patient (47%). Of the 34 respondents who reported the AEFI encountered, more than half of the healthcare workers used a reporting form, 20% made telephone calls and 5% reported using electronic mails. About 56% of respondents reported AEFI encountered either immediately or within 24 h [Table 4]. Of 55 healthcare workers, 31 who had encountered an AEFI reported within 24 h of seeing such. However, no health worker characteristics were found to have any significant association with good reporting practices [Table 5].
|Table 4: Adverse events following immunisation reporting practices of healthcare workers in Alimosho Local Government Area|
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|Table 5: Association between healthcare workers' characteristics and their reporting practices on adverse events following immunisation in Alimosho Local Government Area|
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The most common perceived barriers to not reporting AEFIs are 'not considering the event as related to immunisation' (56.1%) and 'inability to find reporting form' (50.6%) whereas the least perceived barrier to reporting AEFIs was 'lack of time' (48.2%) [Table 6].
|Table 6: Barriers to reporting adverse events following immunisation among healthcare workers in Alimosho Local Government Area|
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| Discussion|| |
Surveillance of AEFI is the bedrock to the sustenance of quality immunisation services in any country. The sensitivity of any AEFI surveillance lies in the awareness, knowledge and reporting practices of healthcare workers, consumers and manufacturers of vaccines. The availability of knowledgeable healthcare workers on the subject, who pay enough attention to observing and reporting AEFIs, is important to assuring continuing public confidence in immunisation programmes. Healthcare workers in this study were found to be fairly knowledgeable on the clinical spectrum and several aspects of AEFI. Four out of five respondents knew the common symptoms of AEFIs such as fever, pain and swelling at injection site. The high level of knowledge of the health workers on the clinical signs of AEFI is in keeping with the high frequency of these symptoms in children post-vaccination as reported from Port-Harcourt, Rivers State, Nigeria. Expectedly, the knowledge of the healthcare workers in this study is much higher than those of mothers in Enugu, where up to 34% of them could not mention any AEFI even though a large proportion of the mothers in Enugu had tertiary level of education.
However, more serious symptoms such as convulsions/seizures and encephalopathy/encephalitis were not as well-known. This suggests some gaps in knowledge and that such not well-known symptoms may be missed or not reported. Two-thirds of respondents knew that unusual conditions thought to be related to immunisation were reportable AEFIs including cases requiring hospitalisation, deaths resulting from AEFI and injection site abscesses. A similar report was also demonstrated in a study by Parrella et al. where most participants opined that events that were life-threatening, rare or previously unknown were reportable AEFIs.
Younger age of healthcare workers was the only factor found to be significantly associated with the knowledge score. This may suggest the influence of exposure to more up-to-date knowledge or personal development on the part of the healthcare workers. The lack of difference in the knowledge between doctors and non-doctors may be difficult to explain or may be attributable in part to the small numbers of healthcare workers studied. The similar performance on knowledge between healthcare workers who had received training on AEFIs and those who had not been trained contrasts with a study on AEFI study among nurses in Kenya where respondents with previous training on AEFI were more likely to have good knowledge on AEFI. The reasons for a lack of effectiveness are uncertain but could be that the trainings on AEFIs received by the healthcare workers in this study were not recent, what was taught had been forgotten or were not impactful. However, our study did not attempt to evaluate the effectives of the training received.
Respondents were conversant with processes of reporting AEFIs in keeping with a quantitative study on healthcare workers' knowledge of AEFI where all the nursing cadre in that study were familiar with paper and telephone reporting procedures. The use of electronic format for reporting AEFIs in this study was low and may be a reflection of limited access to the internet available at the facilities. It should be noted that the frequency of occurrence of serious AEFI is low and it is easy for them to be under-reported or missed completely. Therefore, it is not surprising that only a third of the respondents had ever seen an AEFI in their practice. However, a study by Meranus et al. on AEFI showed that over half (63%) of the healthcare providers in their study had never diagnosed an AEFI. The reporting rate documented in this study was 62% among the 55 respondents who had encountered an AEFI in practice (although not all were within 24 h). This was lower than an Australian study where 93% of the healthcare providers had diagnosed or been involved in the management of a person with AEFI, and 65% of them reported the AEFI.
The proportion of healthcare workers in this study who had seen an AEFI and reported them is slightly higher than the rates reported from an American study on knowledge, attitude and beliefs of healthcare workers on AEFI, in which of the 1607 participants, 40% had diagnosed at least one AEFI and only 19% had reported to the vaccine adverse event reporting system, and in Kenya where 32% of the nurses in that study had diagnosed a reportable AEFI but only 2.3% of them reported. Unlike a report from the UK where nurses reported AEFIs more frequently than other groups, we did not find any significant differences in the reporting practices of doctors and other cadre of healthcare workers including nurses. This may be because our study utilised self-reports rather than observed data of reporting as was done in the UK study. Our inability to find any significant determinants of good reporting practices on AEFIs may be in part to the small numbers of healthcare workers who had encountered them in clinical practice.
The most frequently cited barriers to reporting AEFIs were lack of knowledge of the event and of reporting processes. This is similar to findings in a Zimbabwean study were respondents reported that not being familiar with reporting system significantly affected the reporting rates of AEFI. Likewise in Nigeria, where up to 26% of public sector physicians did not know who to report notifiable infectious diseases to, and 29% did not know about the reporting systems, while 57% reported constraints of time/resource as obstacles to reporting AEFIs. This study similar to all questionnaire surveys suffers from recall bias and an attempt was made at overcoming this by re-phrasing and repeating some questions in the study instrument. Furthermore, reporting practices have been by self-reports which may be overestimated. Although the number of recruited healthcare workers (164) was lower than the planned sample size (178), it was higher than the actual number required without adding the anticipated non-response rate (10%). Furthermore, Noordzij et al. have shown that for a type-1 (alpha) error of 0.05 and type-2 (beta) error of 0.2 (power of 80%), a sample size of 100 would be relatively adequate.
| Conclusion|| |
Although healthcare workers in Alimosho LGA were knowledgeable on several aspects of AEFIs, there were knowledge gaps in recognising more serious AEFIs and low usage of electronic format for reporting AEFIs. Younger age of healthcare workers was found to have a significant relationship with knowledge on AEFIs. We recommend that frequent training of healthcare workers on all aspects of AEFI, especially on injection safety will minimise the occurrence of injection abscess. Musa et al. had demonstrated the effectiveness of a health education intervention to improve both the knowledge and injection safety practices of health worker in Ilorin, Kwara State, Nigeria. We also recommend the use of short messaging services or a short code be made known to mothers patronising health facilities for immunisation so that they can promptly inform healthcare workers should they observe any adverse experiences in their children post-vaccination. This may initially lead to an increase in reporting but will serve as the beginning of a sustainable surveillance system for AEFI. In addition, internet access should be provided to healthcare workers to facilitate the use of electronic methods of reporting AEFIs.
Financial Support and Sponsorship
Conflicts of Interest
There are no conflicts of interest.
| References|| |
Centre for Disease Control and Prevention. Adverse Events Following Immunization: Interpretation and Clinical Definitions Guide – 2011. Available from:http//:www2.gnb.ca>CDC>Healthprofesssionals.
[Last accessed on 2013 Sep 05].
Puliyel J. AEFI and the pentavalent vaccine: Looking for a composite picture. Indian J Med Ethics 2013;10:142-6.
Hu Y, Li Q, Lin L, Chen E, Chen Y, Qi X. Surveillance for adverse events following immunization from 2008 to 2011 in Zhejiang Province, China. Clin Vaccine Immunol 2013;20:211-7.
Aderibigbe SA, Osagbemi GK, Bolarinwa OA. Adverse events following immunization in a Nigerian tertiary health institution. Am J Sci Ind Res 2010;1:496-9.
Maduka O, Tella A, Tobin A, Akpan M. Caregiver experiences with the introduction of pentavalent vaccines in two centers in Port-Harcourt, South-South Nigeria. BJMMR 2015;6:1086-95.
Kohl KS, Marcy SM, Blum M, Connell Jones M, Dagan R, Hansen J, et al.
Fever after immunization: Current concepts and improved future scientific understanding. Clin Infect Dis 2004;39:389-94.
Odusanya OO, Kuyinu YA, Kehinde OA, Francois N, Yarzabal JP, Moreira M, et al.
Immunogenicity, safety and reactogenicity of the 10-valent pneumococcal non-typeable Haemophilus influenzae
protein D conjugate vaccine (PHiD-CV) in Nigerian Infants: A randomised trial. Niger Postgrad Med J 2013;20:272-81.
Erlewyn-Lajeunesse M, Hunt LP, Heath PT, Finn A. Anaphylaxis as an adverse event following immunisation in the UK and Ireland. Arch Dis Child 2012;97:487-90.
Duclos P, Hockin J, Pless R, Lawlor B. Reporting vaccine-associated adverse events. Can Fam Physician 1997;43:1551-6, 1559-60.
McNeil MM, Li R, Pickering S, Real TM, Smith PJ, Pemberton MR. Who is unlikely to report adverse events after vaccinations to the Vaccine Adverse Event Reporting System (VAERS)? Vaccine 2013;31:2673-9.
Ranganathan SS, Houghton JE, Davies DP, Routledge PA. The involvement of nurses in reporting suspected adverse drug reactions: Experience with the meningococcal vaccination scheme. Br J Clin Pharmacol 2003;56:658-63.
Abdulraheem IS, Onajole AT, Jimoh AA, Oladipo AR. Reasons for incomplete vaccination and factors for missed opportunities among rural Nigerian children. J Public Health Epidemiol 2011;3:194-203.
Nnenna TB, Davidson UN, Babatunde OI. Mothers' knowledge and perception of adverse events following immunization in Enugu, South-East, Nigeria. J Vaccines Vaccin 2013;4:202.
Parrella A, Braunack-Mayer A, Gold M, Marshall H, Baghurst P. Healthcare providers' knowledge, experience and challenges of reporting adverse events following immunisation: A qualitative study. BMC Health Serv Res 2013;13:313.
Wanjala CM. Knowledge, Perception and Practice of Nurses on Surveillance of Adverse Event Following Childhood Immunization in Nairobi County, Kenya. Mph thesis. Kenyatta University; 2014. Available from: http://www.ir-library.ku.ac.ke/handle/12345678/12002.
[Last accessed on 2015 Aug 04].
Meranus D, Stergachis A, Arnold J, Duchin J. Assessing vaccine safety communication with healthcare providers in a large urban county. Pharmacoepidemiol Drug Saf 2012;21:269-75.
Hutchinson P, Nelson M, Hill S, Duran L, Engler R. Knowledge, attitudes and beliefs (KAB) regarding reporting of adverse events following immunization (AEFI). J Allergy Clin Immunol 2007;119:S96.
Muchekeza M, Chimusoro A, Nomagugu N, Kafakwanguzvarova WP. Adverse event following immunization (AEFI) surveillance in Kwekwe district, Midlands Province, Zimbabwe, 2009-2010. J Vaccines Vaccin 2014;5:232.
Lafond K, Dalhatu I, Shinde K, Ekanem EE, Ahmed S, Peebles P, et al
. Notifiable disease reporting system among public sector physicians in Nigeria: A cross-sectional survey to evaluate possible barriers and identify best sources of information. BMC Health Serv Res 2014;14:568.
Noordzij M, Tripepi G, Dekker FW, Zoccali C, Tanck MW, Jager KJ. Sample size calculations: Basic principles and common pitfalls. Nephrol Dial Transplant 2010;25:1388-93.
Musa OI, Parakoyi DB, Akanbi AA. Evaluation of health education intervention on safe immunization injection among health workers in Ilorin, Nigeria. Ann Afr Med 2006;5:122-8.
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]