|Year : 2023 | Volume
| Issue : 1 | Page : 101-105
Effectiveness and adverse effects of astrazeneca and pfizer COVID-19 vaccines among medical students in Oman: A comparative study
Mohan Bilikallahalli Sannathimmappa1, Vinod Nambiar1, Rajeev Aravindakshan2, Muqeet Fauzan Baig1, Ahmed Kifah Hassan1, Maryam Saud Mohammed Al-Balushi1
1 Department of Microbiology, College of Medicine and Health Sciences, National University of Science and Technology, Sohar, Oman
2 Department of Community Medicine, All India Institute of Medical Sciences, Mangalagiri, Andhra Pradesh, India
|Date of Submission||12-Nov-2022|
|Date of Decision||26-Jan-2023|
|Date of Acceptance||10-Feb-2023|
|Date of Web Publication||14-Mar-2023|
Mohan Bilikallahalli Sannathimmappa
Department of Microbiology, College of Medicine and Health Sciences, P O Box: 391, PC: 321, Al Tareef, Sohar
Source of Support: None, Conflict of Interest: None
Background: Immunization against severe acute respiratory syndrome coronavirus 2 became necessary to control the menace of COVID-19. However, the safety of COVID-19 vaccines must be monitored continuously. The present study aims at comparing the effectiveness and adverse effects of Pfizer and AstraZeneca vaccines among the cohort of medical students. Methods: It was a single-cohort comparative study, and the data were collected using an online survey from participants who took at least two doses of AstraZeneca or Pfizer vaccines. The data included demography, breakthrough infections, and adverse effects following vaccination. Bivariate and logistic regression models were used to find associations between effectiveness and independent variables. Statistical significance was considered at P < 0.05. Results: In total, 115 students who had received Pfizer or AstraZeneca vaccines were included in the study. The mean age of the participants was 21.52. Female (n = 90) participants were more compared to males (n = 25). The majority of them received Pfizer vaccine (95), while AstraZeneca was received by only 20 participants. Overall effectiveness of both AstraZeneca and Pfizer was nearly 85%, while almost 100% protection was observed among those who were vaccinated after contracting the disease. Logistic regression revealed an independent effect of COVID-19 before any vaccination dose offered 66% protection against any subsequent breakthroughs (odds ratio 0.44, 95% confidence interval [CI]: 0.095–2.08). At least one adverse effect was reported by 96 (83.5%) participants (95% CI: 75.4%–89.75%). Pain at the site of injection, fever, generalized weakness, and headache were the most common adverse effects. Fever (P < 0.001), body ache (P < 0.001), generalized weakness (P = 0.002), and joint pain (P = 0.014) were significantly more common in AstraZeneca as compared to Pfizer. Conclusion: Coronavirus vaccines were well tolerated, safe, and induced protection in most participants. Most postvaccine adverse events were mild to moderate, mainly due to induction of immune response by the body for protection. Furthermore, these mild to moderate adverse effects should not be hindrance to vaccination.
Keywords: Adverse effects, Astrazeneca, breakthrough infection, effectiveness, Pfizer
|How to cite this article:|
Sannathimmappa MB, Nambiar V, Aravindakshan R, Baig MF, Hassan AK, Al-Balushi MS. Effectiveness and adverse effects of astrazeneca and pfizer COVID-19 vaccines among medical students in Oman: A comparative study. Biomed Biotechnol Res J 2023;7:101-5
|How to cite this URL:|
Sannathimmappa MB, Nambiar V, Aravindakshan R, Baig MF, Hassan AK, Al-Balushi MS. Effectiveness and adverse effects of astrazeneca and pfizer COVID-19 vaccines among medical students in Oman: A comparative study. Biomed Biotechnol Res J [serial online] 2023 [cited 2023 Jun 5];7:101-5. Available from: https://www.bmbtrj.org/text.asp?2023/7/1/101/371703
| Introduction|| |
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) since its emergence in December 2019 has had negative impact on global health and the economy.,, Up to May 23, 2022, more than 527 million were reported to be infected by SARS-CoV-2 and it has claimed more than 6.3 million lives globally. In response to this adversity, many candidate vaccines have been tried, but few of them were approved for human use after they passed efficacy and safety standards. Pfizer–BioNTech mRNA vaccine (BNT162b2) and the Oxford–AstraZeneca adenovirus-vectored vaccine (ChAdOx1 nCoV-19) were the two most widely administered vaccines worldwide. Both vaccines target the surface “S” protein and vaccination induces the production of antibodies against S protein. These antibodies adhere to S protein and prevent the virus from entering the cells. The two-dose AstraZeneca and Pfizer vaccination campaigns substantially reduced hospitalization and deaths globally. Despite the successful development of COVID-19 vaccines, none of the vaccines provide absolute or lifelong protection in vaccinated individuals. In some cases, vaccines fail to induce protective levels of antibodies or result in the gradual waning of immunity within a few weeks to months of vaccination. However, protection against severe disease, hospitalization, and death remained high even for 6 months after vaccination for both AstraZeneca and Pfizer vaccines., A systemic review showed effectiveness against symptomatic SARS-CoV-2 infection in the general population to be 87%–97% and 92% for Pfizer and AstraZeneca vaccines, respectively. However, the protection rate dropped to 44% and 62.5%, respectively, for AstraZeneca and Pfizer vaccines by 20 weeks.,, In addition, an Israeli National Database reported a considerable increase in the risk of infection after 6 months of vaccination. With the recent emergence of variants of SARS-CoV-2, several countries recommended booster doses after 6 months of the second dose for high-risk individuals to mitigate COVID-19.
Following the approval and use of these vaccines, several studies across the globe were conducted. They revealed both Pfizer and AstraZeneca have a good safety profile with some minor, short-lived, and self-limiting adverse effects. Pain at the site of injection, headache, fever, fatigue, lymphadenopathy, nausea, vomiting, loss of smell, dyspnea, and others were the common adverse effects observed. In addition, some rare but serious adverse effects such as myocarditis, blood clots, anaphylaxis, and others were also reported. The aim of this study was to investigate the adverse effects and infection rates among vaccinated undergraduate medical students.
| Methods|| |
The present single-cohort comparative study was conducted in the Department of Microbiology and Immunology, College of Medicine and Health Sciences (COMHS), National University. The study participants were medical students of COMHS. All students were briefed about the study and the students who showed a willingness to participate were included in the study. Participants were invited to participate in the online survey-based study during November–December 2021.
Students who received Pfizer or AstraZeneca vaccine were included in the study.
Students who received COVID-19 vaccines other than Pfizer and AstraZeneca were excluded from the study.
The questionnaire was constructed by the research team based on the available literature. A draft questionnaire was validated by a group of experts to provide their feedback and the questions were modified accordingly. The final draft was tested on 30 participants regarding the comprehensibility of the questions. The questions were then modified as required. The final questionnaire was prepared in Google Forms and sent to all the participants to fill in and submit the filled-in form. Participants were asked questions regarding their demography, details of vaccination, and history regarding COVID-19 disease.
Data were downloaded from Google Sheets and cleaned for logical errors. The final dataset was analyzed using Statistical Package for the Social Sciences (SPSS) software, version 22 (SPSS Inc., Armonk, NY: IBM Corp). Frequency analysis of all the categorical variables was done and percentages were calculated. Graphical analysis was performed wherever necessary. Groups were defined by the vaccine used in the 1st and 2nd doses and also by the experience of COVID-19 before the vaccinations as hybrid immunity. Effectiveness was deemed as the percentage of those unaffected by breakthroughs in each group. Logistic regression was carried out to explain the effect of the combined effect of previous infection along with subsequent vaccination for COVID-19 on immunity against breakthrough infections.
| Results|| |
[Table 1] represents the demographic characteristics of the study participants. Of the total 115 participants, 90 (78.3%) and 25 (21.7%) were females and males, respectively. The mean age of the participants was 21.52. Female (n = 90) participants were more compared to males (n = 25). Nationalities were mixed with the majority belonging to the Sultanate of Oman (62.6%)). There were 15 (13%) from Iraq and the remaining (24.4%) were variously from 11 countries. Majority of them received Pfizer vaccine (95), while AstraZeneca was received by only 20 participants. Overall effectiveness of both AstraZeneca and Pfizer was nearly 85%, while almost 100% protection against breakthrough infection was observed among those who were vaccinated after contracting the disease. Logistic regression produced a significant model (Nagelkerke R Square = 0.022) when variable on COVID-19 before any vaccination dose was included in the model which seemingly offered 66% protection against any subsequent breakthroughs (odds ratio 0.44, 95% confidence interval [CI]: 0.095–2.08). Comorbidities were present in 24 participants and 9 of them had been infected with COVID-19 before starting vaccination (P < 0.001). All participants were immunized with vaccines, predominantly by Pfizer (95). Twenty were immunized with AstraZeneca vaccine which was available a little earlier than the former, i.e., by February 2021.
[Figure 1] depicts the month-wise administration of vaccination to the participants. The vaccination was initiated in January 2021 and 21 of them got infected before the doses could be completed as per the original schedule. Hence, 21 of the 115 became the hybrid immunity group by way of being infected before vaccination. Majority of the students took the vaccine during the months of June and July 2021.
[Figure 2] displays various vaccine adverse effects that our study participants experienced. Among 115 vaccinated individuals, 96 (83.5%) experienced at least one adverse effect (95% CI: 75.4%–89.75%). Pain at the site of injection (90) was the most reported local adverse effect, followed by generalized weakness, fever, headache, joint pains, and others. Pain, fever, body ache, generalized weakness, and joint pain were significantly more common in AstraZeneca as compared to Pfizer.
|Figure 2: Comparison of adverse effects of Pfizer and AstraZeneca vaccines|
Click here to view
[Table 2] highlights the occurrence of COVID-19 following Pfizer or AstraZeneca vaccination among the participants. Three out of 20 (15%) and 12 out of 90 (14.4%) participants developed COVID-19 following 1 week to more than 2 weeks of vaccination with AstraZeneca and Pfizer vaccines, respectively. All of them developed an infection after the second dose of vaccination after 2 weeks except in one who got infected within 1–2 weeks of AstraZeneca vaccine. All of them had mild infection except one who developed moderate infection and was treated at home.
| Discussion|| |
The COVID-19 vaccine drive in Oman was started in December 2020, initially prioritizing high-risk individuals such as health-care workers, the elderly, and people with immunocompromised individuals. Subsequently, the vaccine drive targeted all nationals and expatriates of age more than 12 years. AstraZeneca and Pfizer were the two vaccines widely administered in Oman. All medical students of COMHS completed their academic year 2020–21 through online education. Ministry of Health in Oman gave directives to all higher education institutes in Oman to mandate the in-person session to students in the academic year 2021–22 that started from September 2021 and made it compulsory to allow students to enter the campuses only if they were fully vaccinated with COVID-19 vaccines. Therefore, all our participants were fully vaccinated with COVID-19 vaccines. Majority of them were vaccinated with Pfizer vaccine since it was easily available though it was expensive compared to AstraZeneca vaccine, which was another vaccine widely administered in Oman. Majority of them took in the months of June and July 2021 because of the strict orders from the Ministry of Health.
Literature studies indicate no COVID-19 vaccines give complete protection and breakthrough infection was reported among the small percentage of vaccinated individuals. A systematic review of 39 studies reported a high level of protection by Pfizer (87%–97%) and AstraZeneca (92%) against symptomatic SARS-CoV-2 infection. However, the duration of protection is short-lived and vaccine effectiveness gradually drops after a few weeks of vaccination and the risk of infection considerably increases after 6 months of vaccination.,, Studies by Andrews et al. and Mahase reported a dropping of protection rate to 44% and 63% for AstraZeneca and Pfizer vaccines, respectively, by 20 weeks after the second dose of vaccination., Similar to these studies, the vaccine protection rate observed in our participants was nearly 85% for both types of vaccines. Despite the high efficacy, rare breakthrough infections have been reported among health-care workers and the general population. In about 15% of our participants, breakthrough infections were noticed after 2 weeks of the second dose of vaccination in all except in one who developed an infection within 1–2 weeks of the second dose. Breakthrough infections in fully vaccinated individuals are generally of mild-to-moderate degree. Thus, vaccination plays a key role in reducing hospitalization and mortality. In line with this, breakthrough infections in our study participants were mild to moderate in nature.
Knowledge about COVID-19 vaccine benefits and adverse effects is crucial for improving public vaccine acceptance. Most people develop immunity following vaccination regardless of the presence or absence of adverse effects. In general, COVID-19 vaccines are well tolerated with most developing only mild-to-moderate self-limiting adverse effects. According to World Health Organization, the most common adverse effects following COVID-19 vaccines are pain at the site of injection, fever, headache, generalized body aches, joint pains, and others. A recently published study reported postvaccine mild-to-moderate adverse effects more common among younger age groups and the adverse effects result from the body's immune response to vaccine antigen to induce the production of protective antibodies. Therefore, the benefits from vaccination are many folds compared to mild-to-moderate well-tolerable adverse effects. In our study participants, pain at the site of injection, fever, generalized weakness, and headache were the most observed adverse effects. They were significantly high among those who received AstraZeneca compared to Pfizer. Rarely, COVID-19 vaccines can lead to more serious adverse effects such as myocarditis, blood clots, and anaphylaxis. Fortunately, none of our study participants developed serious vaccine-related complications. Therefore, these mild-to-moderate adverse effects should not be a hindrance to subsequent booster vaccination, especially for individuals with comorbidity as they are at high risk of developing serious COVID-19 infection.
Our study has several limitations, and we advise caution in the interpretation of the findings. First, the sample size was small, and all participants were young medical students and hence it is difficult to extrapolate the results to the broader population. Second, based on such a small sample size, it is difficult to conclude the eventual adverse effect profile of the Pfizer and AstraZeneca vaccines. Third, the study did not distinguish the severity of adverse effects following 1st and 2nd dose, though adverse effects are more common after the second dose. Finally, the study was survey-based, and hence results need to be confirmed by experimental studies.
| Conclusion|| |
From the study results, it can be concluded that both Pfizer and AstraZeneca have a significantly higher rate of protection against SARS-CoV-2 infection. Moreover, they significantly reduce the occurrence of severe infection and thus reduce hospitalization and mortality. Most of the vaccine adverse effects were mild to moderate, indicating they are well tolerated, and these adverse effects should not be a hindrance for vaccination. However, to have a clearer picture of the adverse effects, large sample sizes, and multicenter studies are highly recommended.
The current study was approved by the Institutional Research and Ethic Committee [Approval no: NU/COMHS/EBC0017/2022].
We acknowledge all participants of College of Medicine and Health Sciences, National University of Science and Technology for their active participation and helping us to complete the study.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]
[Table 1], [Table 2]