The acceptability and side effects of COVID-19 vaccine among health care workers in Nigeria: a cross-sectional study [version 2; peer review: 2 approved with reservations]

Background : The COVID-19 pandemic is global public health crisis. Mass vaccination, until herd immunity is achieved, is one of the most effective ways of combating the deadly infectious virus. The disposition of health workers towards the AstraZeneca vaccine will most likely determine if other members of the community will be willing to get vaccinated or not. Thus, the purpose of this study is to determine the attitudes of healthcare workers to the COVID-19 vaccine, as well as determine the various side effects experienced by those who have already been vaccinated. Method : Frequency tables were created, and Chi-square was used to determine the relationship between respondents' socio-demographic characteristics, as well as their acceptance or rejection of the COVID-19 vaccine and attitude towards it. Using IBM SPSS Statistics for Windows, version 22.0, multinominal logistic regression was used to determine the key factors which influenced respondents’ decision to have the vaccine. Result : There was a statistically significant relationship between the pain at the injection site. Public awareness of the vaccine and its benefits should be increased, and the vaccine should be made available in all health care facilities. This article is included in the Emerging Diseases and Outbreaks gateway. This article is included in the Coronavirus collection. calculated mean were considered to have a positive attitude towards the AstraZeneca vaccine, while those who scored lower than the calculated mean were considered to have a negative attitude toward the vaccine. The questions on the respondents ’ willingness to accept the vaccine and the readiness to recommend same for others were scored 1 for a ‘ yes ’ answerand0fora ‘ no ’ answer.Vaccineacceptabilitywasdeterminedbyaddingthescoresfor willingnesstobevaccinated and readiness to recommend the vaccine to patients. The mean was calculated after adding up all the scores. Respondents with scores lower than the mean were considered to have poor acceptability, while those with scores higher than the mean wereconsideredtohavegoodacceptability.DatawasanalysedusingSPSSversion22,aftersorting.Frequencytableswerecreated,andtheChisquaretestwasusedtodeterminetherelationshipbetweenrespondents ’ socio-demographic characteristics, as well as their attitude and acceptability of the AstraZeneca COVID-19 vaccine. The factors influencing COVID-19acceptabilitywere identified usingmultinominallogistic regression.Tribeofrespondents,cadreaswellaspast involvement in management of COVID-19, were tested for their association with vaccine acceptability at the multivariate level. This study aims to determine the willingness and acceptability of COVID-19 vaccination among Nigerian health care workers, as well as the potential side effects among those who have already been vaccinated. A higher proportion of health workers were willing to get vaccinated with AstraZeneca vaccine available in Nigeria than a similar study done among health workers in France and the French-speaking part of Belgium, which had a 46.8% acceptance rate of the same AstraZeneca vaccine. 7 Our findings could be attributed to increased vaccine awareness. Despite the widespread misconception about vaccination, health care worker ’ s acceptance of the COVID-19 vaccine will go a long way toward informing patients about the importance of getting vaccinated.


Introduction
Following its emergence in Wuhan, China, in November 2019, the coronavirus disease (COVID-19) was declared a global pandemic in March 2020. 1 Globally, there were 126,359,540 confirmed COVID-19 cases and 2,769,473 deaths as of 28 th March 2021. On the 30 th January 2020, COVID-19 was declared as Public Health of International concern (PHEIC) by the World Health Organization (WHO). The disease has ravaged more than 200 countries worldwide, which necessitated its declaration as a global pandemic in March 2020.
COVID-19 was first detected in Nigeria on 24 th March 2020. Since then, the pandemic has spread rapidly throughout the country, with over 146,000 cases and 2402 deaths as of 16 th March 2021. The Nigerian healthcare system was unprepared for the pandemic; facing issues such as a lack of training and retraining of health workers on disease preparedness, lack of personal protective equipment, lack of testing centres in many cities, and unwillingness to be tested. 2 Different national governments have imposed a number of measures and protocols to help halt the spread of COVID-19, including the mandatory wearing of face masks, lockdowns, social distancing, and frequent hand washing with soap and water, among other measures. Following the introduction of the non-pharmaceutical interventions, vaccines have been developed to curb the spread of COVID-19 infection. 2 Herd immunity is defined as the indirect protection from an infectious disease that happens when a large proportion of a population is immune to an infection either through vaccination or immunity developed through previous infection.
Vaccination is an effective method of combating infectious diseases by training the immune system to recognize and combat pathogens, either viruses or bacteria. 3 Pharmaceutical companies and researchers around the world have collaborated to develop safe and effective vaccines. Pfizer, Sinovac, Janssen, Oxford/AstraZeneca, Moderna, Sputnik V, and Sinopharm are among the companies that have produced COVID-19 vaccines to combat the virus's spread. 4 The AstraZeneca vaccine was the only vaccine available for use in Nigeria as at the time of this study and it is the vaccine still currently being given. AstraZeneca was rolled out in Nigeria on the 18 th of February 2021, however at the time of study, vaccinations had not commenced in some states. The vaccine is available free of charge to all, at government health facilities throughout Nigeria. The availability of a vaccine does of course not guarantee its uptake, and the acceptance of the COVID-19 vaccination is entirely voluntary in Nigeria. In a study done among healthcare providers in Nigeria on COVID-19 vaccine acceptability, 53.5% of respondents were willing to get vaccinated against the disease and the reason why 69.4% of respondents will not receive the COVID-19 vaccine was because of fear of side effects. 5 To curb COVID-19, experts estimate that herd immunity would require around 80-90% of the population to have COVID-19 immunity. Hence there is a need to get the populace immunized. 6 Health care workers are an important group to consider, as they are in a pivotal position to determine if other members of the populace will be willing to get vaccinated or not. 7 Health care workers are a reliable source of vaccination information to the general public and thus their acceptance or rejection of the COVID-19 vaccine may be critical to its uptake among the general population. 7 Identifying the reasons why healthcare workers may be hesitant to take the COVID-19 vaccine could be used to inform policy makers, in modifying such factors to ensure better attitudes towards vaccination, and thus increased herd immunity. 8 The purpose of this study is to determine the acceptability of the COVID-19 vaccine among healthcare workers, as well as the various side effects experienced by those who have already been vaccinated. Knowledge of the side effect will help pharmaceutical companies modify the production of the vaccines in order to limit the side effects.

REVISED Amendments from Version 1
Second line under methods in abstract, "or rejection" was deleted. The second sentence under methods was restructured to portray the actual meaning intended. The third paragraph under introduction have been restructured. Methods have been changed to methodology. Study design and data collection has been added as a subtitle under methodology. Ethical consideration has been removed from under data collection and moved towards the end of methodology, just before the result. Limitation of the study has been included in the manuscript. Major side effect has discovered from the study has been included to the conclusion.
Any further responses from the reviewers can be found at the end of the article Methodology Study design and data collection Respondents took part in a cross-sectional study by filling out an online survey through Google forms; all participants were health workers from Nigeria's six geopolitical zones. Health care workers in different health institutions across the six geopolitical zones in Nigeria who were colleagues and former colleagues of the authors were randomly selected and contacted through their already known phone numbers. They helped to circulate the link on their various hospital health workers' WhatsApp groups. Respondents' WhatsApp details were obtained from their colleagues. Some participants also shared the link via e-mails to colleagues who were not active on WhatsApp. The respondents did not undergo any form of screening before they were recruited. The introductory part of the Google form contained a statement on the aim and details of the study and it also contained a request for the patient's consent to be part of the study. The Google form was designed to learn about the participants' attitudes towards the vaccine, side effects experienced by those already vaccinated, and willingness to get vaccinated (Extended data (Ilori et al., 2021)). The survey was available to participants from the 23 rd March 2021 to the 3 rd May 2021. Only responses that were completed were counted and recorded. Surveys completed by respondents with the same email address were disqualified because they were deemed to be overlapping responses.

Sample size and analysis
A total of 309 responses were collected and analysed using SPSS version 22. 9 Questions 1-6 were on sociodemographic characteristics of respondents, questions 7-19 handled the willingness to get vaccinated and questions 20-27 answered the attitudinal questions. After data collection, numbers were assigned to answers for the purpose of computing. Respondents' attitudes were graded by assigning scores to the likert scale responses. All the likert scale questions were negative except the penultimate and the last questions which were neutral and positive respectively. For the negative statements, strongly agreed, agree, indifferent, disagree and strongly disagree corresponds to scores of 1,2,3,4,5 respectively. For the positive statement, strongly agreed, agree, indifferent, disagree and strongly disagree corresponds to 5,4,3,2,1 respectively. The mean was calculated by adding the sum of all the scores for all respondents. Respondents who scored higher than the calculated mean were considered to have a positive attitude towards the AstraZeneca vaccine, while those who scored lower than the calculated mean were considered to have a negative attitude toward the vaccine. The questions on the respondents' willingness to accept the vaccine and the readiness to recommend same for others were scored 1 for a 'yes' answer and 0 for a 'no' answer. Vaccine acceptability was determined by adding the scores for willingness to be vaccinated and readiness to recommend the vaccine to patients. The mean was calculated after adding up all the scores. Respondents with scores lower than the mean were considered to have poor acceptability, while those with scores higher than the mean were considered to have good acceptability. Data was analysed using SPSS version 22, after sorting. Frequency tables were created, and the Chi square test was used to determine the relationship between respondents' socio-demographic characteristics, as well as their attitude and acceptability of the AstraZeneca COVID-19 vaccine. The factors influencing COVID-19 acceptability were identified using multinominal logistic regression. Tribe of respondents, cadre as well as past involvement in management of COVID-19, were tested for their association with vaccine acceptability at the multivariate level.

Ethical consideration
The research team obtained approval from the Ethical Review Committee of LAUTECH Teaching Hospital, Ogbomoso.

Limitation of the study
Being an online study, it may not have covered other prospective respondents who do not have internet facilities. Table 1 shows that 195 respondents were female, while 114 (36.9 %) were male. The majority (82.2%) were Yorubas, and 237 (76.7%) were Christians. The majority of the respondents came from the geopolitical zone of the South West. 121 respondents (39.2%) were Doctors, 89 (28.8%) were Community Health Extension Workers (CHEWs) and 57 (18.4%) were Nurses. Physiotherapists, Pharmacists, and Porters were among the 17% (5.4 percent). Table 2: At the time of this research, 238 respondents (80.3%) were willing to be vaccinated, and 117 (37.9%) were already vaccinated; the majority of whom were only one week away from the day of vaccination. The reason given by 127 (66.2%) of those who had not been vaccinated was that the vaccine was not yet available in their facility. Even if the vaccine was made available, 41 (60.3%) of respondents would not get vaccinated because they are not just at peace with the vaccine. Table 3 shows that 250 (80.9%), 250 (80.9%), and 111 (35.9%) of respondents can recommend COVID-19 vaccine to their patients, have attended COVID-19 seminars, and have been involved in the care of COVID-19 patients. Table 4 shows that 85 respondents (72.6%) experienced side effects after receiving the COVID-19 vaccine, while 32 (27.4%) did not. 73 participants (85.9%) reported pain at the injection site, while 36 (42.3%) and 34 (40.0%) reported fever and headache, respectively. Table 5 shows that 168 (54.4%) of respondents had a positive attitude toward COVID-19 vaccination, while 141 (45.6%) had a negative attitude. Table 6 shows that 237 (76.7%) of respondents thought the COVID-19 vaccine was acceptable, while 72 (23.3%) had a poor acceptability of the vaccine. Table 7 shows a statistically significant relationship between respondent's tribe and cadre, and their attitude toward COVID-19 vaccination. More males and respondents of Christian religion had good attitude towards COVID-19 vaccination Table 8: When compared to their acceptability of COVID-19 vaccination, there is a statistically significant association between tribe and cadre of respondents; more laboratory scientists had poor acceptability of the COVID-19 vaccination, while a high proportion of CHEWs had good acceptability of the COVID-19 vaccination. Table 9 lists the predictors of COVID-19 vaccine acceptability among health workers, which include Tribe, Cadre, and involvement in the care of a COVID-19 patient. The Igbo and other tribes are 3.962 and 3.631 times more likely, respectively, to accept the COVID-19 vaccine, than the Yoruba tribe. When compared to Doctors, CHEWS are 0.048 times less likely to accept COVID-19 vaccination. Participants who have been involved in the care of a COVID-19 patient are 1.824 times more likely than those who have not to accept the vaccine.

Discussion
This study aims to determine the willingness and acceptability of COVID-19 vaccination among Nigerian health care workers, as well as the potential side effects among those who have already been vaccinated. A higher proportion of health workers were willing to get vaccinated with AstraZeneca vaccine available in Nigeria than a similar study done among health workers in France and the French-speaking part of Belgium, which had a 46.8% acceptance rate of the same AstraZeneca vaccine. 7 Our findings could be attributed to increased vaccine awareness. Despite the widespread misconception about vaccination, health care worker's acceptance of the COVID-19 vaccine will go a long way toward informing patients about the importance of getting vaccinated.  Our findings are quite different from another study conducted in Ghana, where there was a self-reported, low intention of health workers to accept the AstraZeneca vaccine. 4 The reason for this similarity may because of several myths about the vaccine as well as the rapidity in the development of the vaccine. Some of the myths and misconception about the vaccine are that there was inadequate clinical trials to support its usage, mutation of gene etc. 10 Many respondents may have been sceptical about the Nigerian government's ability to intervene by providing a liable vaccine within a year of the commencement of the pandemic in such a short period of time. Continuous public sensitization about the benefits of getting vaccinated against this infectious disease will go a long way toward convincing health workers and the general population in this category to reconsider accepting the vaccine. In study conducted in Saudi Arabia between 8 th December to 14 th December 2020, out of 673 health workers sampled, half were willing to receive the COVID-19 vaccine, and 49.71% planned to do so as soon as it became available. 11 Their findings are comparable to those in this study, in which more than three-quarters of respondents said they would get vaccinated as soon as they could. This is very encouraging because a high vaccination rate is essential to achieving herd immunity within the global population and working towards managing the spread of the virus.   The AstraZeneca COVID-19 vaccine's side effects have been widely documented within research. In a study conducted in the United Kingdom, among Pfizer-BioNTech vaccine recipients, two-thirds of those polled reported one or more side effects, with fatigue and headache being the most common. 12 This is in contrast to the findings of the current study, which found that pain at the injection site was the most common side effect experienced. The likely reason for this is due to the different types of vaccines used in both study areas. There is an urgent need for the manufacturers to ensure that the side effects of these vaccines, regardless of type, are kept to a minimum to encourage greater acceptance.
In a similar study conducted among health care workers in New York, USA, gender, age, and place of residence were statistically significant with the willingness to get vaccinated with BioNTech Pfizer COVID-19 vaccine. 10 However, in this study, the statistically significant factors were cadre of health care workers and their tribe. The probable reason why tribe is statistically significant may be because tribal values are held in high esteem in African communities. Thus, people of the same tribe tend to share similar views about general health issues including vaccination. Furthermore, when compared to CHEWs, doctors were more willing to accept the vaccination. The reason for this among the various cadres of health workers may be that doctors are more likely have had the opportunity to treat as well as witness complications associated with COVID-related illnesses, than the other cadres of health care workers. This could explain why those who had previously been involved in the care and management of COVID-19 patients were significantly more likely to accept COVID-19 vaccination than those who have never treated COVID-19 patients.
In terms of the limitations of the study, considering the fact that the study was conducted online, only respondents who got the link through WhatsApp or e-mail alone were able to respond to the questions. Thus, it is not every health worker that is active on WhatsApp and there is no common data base where email of all health workers could be assessed.

Conclusion
In this study, the rate of acceptance of COVID-19 vaccination among health workers was quite high, especially among doctors when compared with other cadres. The acceptability of COVID-19 vaccination was statistically significant by tribe and cadre of respondents, and health workers who had been involved in COVID-19 management were more likely to accept the vaccine. The main reason respondents would not get vaccinated was the fear of side effects which was closely linked to various myths accrued to AstraZeneca vaccines available in Nigeria, such as getting infected with the virus through the vaccine, alteration of recipient's gene etc. Pain at injection site was the most common side effect experienced by health workers who had been vaccinated with the COVID-19 vaccine. To encourage vaccine acceptability by the general population, side effects from COVID-19 vaccine, regardless of the brand, should be kept to a minimum.

Open Peer Review
Current Peer Review Status:

Version 1
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