Impact of age, sex and medical history on adverse reactions to the first and second dose of BNT162b2 mRNA COVID-19 vaccine in Japan: a cross-sectional study

Effects of age and gender on immunogenicity and reactogenicity of SpikoGen recombinant spike protein vaccine: a post-hoc analysis

SpikoGen® COVID-19 vaccine is based on the spike protein extracellular domain of the ancestral Wuhan-Hu-1 strain modified by removal of the furin cleavage site and addition of stabilising mutations expressed as a recombinant protein in insect cells. It is formulated with Advax-CpG55.2™ adjuvant to ensure optimal immunogenicity. In this study, data from several SpikoGen® clinical trials was retrospectively analysed to assess for any effect of gender or age on seroconversion, neutralizing antibody levels or the incidence of adverse events. Following the 1st dose, older age was associated with a reduced rate of fatigue (RR 0.97, p < 0.001), headache (RR 0.98, p = 0.034) and myalgia (RR 0.97, p=0.016), following the 2nd dose, the rate of fatigue (RR 0.98, p = 0.017) but following the 3rd dose no effect of age on adverse events was evident. Similarly, following the 1st dose, men reported a 19% lower incidence of fatigue, 36% lower incidence of headache and 28% lower incidence of myalgia when compared to women. Interestingly, there was no relationship between age or gender and serum neutralizing antibody levels, although after each vaccine dose there was a consistent trend to women having a higher seroconversion rate. There was no correlation between neutralizing antibody levels and adverse events. Unlike what is seen with mRNA vaccines, reactogenicity trended lower after each subsequent SpikoGen® dose. Overall, SpikoGen® exhibited positive immunogenicity and low reactogenicity, indicating that a low incidence of adverse events does not equate to poor immunogenicity. SpikoGen® remains a promising protein-based vaccine platform for COVID-19 protection.

Medical occurrence and safety of SARS-CoV-2 vaccination outside of the hospital setting

During COVID-19 pandemic, vaccination has been strongly recommended and advocated to prevent COVID-19 infection and adverse outcomes, particularly among at-risk populations. The vaccination against SARS-CoV-2 (COVAC) occurred at off-site locations capable of accommodating large crowds, distinct from the hospital setting, where a team of intensivists, emergency physicians, and nurses, ensuring prompt medical attention (medical occurrences, MO) in cases of adverse event following immunization. Our aims were to estimate the incidence of MO, and to assess its association with demographics, and vaccine characteristics. Our retrospective cohort study included all subject aged 12 years and older who received vaccinations at two large out-of-hospital vaccination hubs (Fiera Milano City, Palazzo delle Scintille), between April 12th and August 31st, 2021. Nine hundred and ninety-five thousand and twenty-eight vaccinations were administrated. MOs incidence rate was 278/100,000 doses (95% confidence interval (CI) 268-289). Most MOs were mild (86.27%) and mainly observed in subjects who received the Comirnaty vaccine; 92 MOs (3.32%) were severe and mostly occurred in recipients of the Vaxzeria vaccine. The incidence rate for hospital transfers following vaccination was 4.7/100,000 doses (95% CI 3.5-6.2) and any level of anaphylaxis occurred in 0.4 cases per 100,000 administrated doses (95% CI 0.3.-0.7). Sex, age, type of vaccine and first dose were associated with incidence of MO. Our results showed a low incidence rate in MOs after COVAC, mainly mild and support the feasibility, effectiveness and safety of vaccinations administered in hubs with a dedicated SEU located outside of the hospital setting.

Safety profiles of homologous and heterologous regimens containing three major types of COVID-19 vaccine among people living with HIV

BACKGROUND

Existing data on adverse effects (AEs) of homologous and heterologous COVID-19 vaccine regimens among people living with HIV (PLHIV) are limited.

METHODS

A prospective cohort study was conducted among Thai PLHIV during 2021-2022. Vaccine types and AEs were collected using an online survey.

RESULTS

Of the 398 vaccinated PLHIV, 92% had CD4 count ≥200 cells/µL and 96% were virologically suppressed at enrolment; 38% received two doses and 62% received three doses of COVID-19 vaccines. Inactivated, viral vector and mRNA were the most common vaccine types received as the first, second, and booster doses, respectively. For the first and second vaccine doses, the most common AEs were fever (15% and 11%) and injection site pain (11% and 11%). The mRNA vaccine significantly caused more overall AEs, injection pain, fatigue, and rashes than the other two types. For a booster dose, viral vector vaccine significantly caused more injection site pain and headache than the other two types. The majority of AEs of the first, second and booster doses spontaneously recovered without treatment. By multivariable analysis, receipt of viral vector or mRNA vaccine and age less than 40 years were independently associated with AEs of the primary series vaccines, while having AEs from the previous dose and female sex were independent factors associated with AEs of a booster vaccine.

CONCLUSIONS

Our study suggested the safety of homologous and heterologous regimens containing the three types of COVID-19 vaccines among PLHIV and identified those who required close monitoring for vaccine AEs.

Association Between Electronic Device Use at Bedtime and COVID-19 Vaccine-Related Adverse Events During the COVID-19 Pandemic in Korean Adults: A Nationwide Cross-Sectional Population-Based Study

BACKGROUND

The coronavirus disease 2019 (COVID-19) pandemic has led to heightened mood disturbances linked to increased electronic device use at bedtime (EUB). General anxiety may contribute to an increased likelihood of experiencing nocebo responses, which have been reported to be associated with COVID-19 vaccine-related adverse events (CAEs). However, no related studies have been conducted to examine this association to date.

METHODS

We executed a nationwide cross-sectional study to explore these correlations during the pandemic. Using data from the 2022 National Sleep Survey of South Korea, we analyzed the sleep health of 4,000 adults aged 20-69 years between January and February 2022. Shift workers and those with severe sleep disorders were excluded. Participants with EUB more than four days a week were labeled as high frequency EUB, and those reporting CAEs after both vaccine doses were marked as having a presence of CAEs. The survey also included details about anthropometric data, socioeconomic status, and sleep status.

RESULTS

Of the 3,702 participants, 92.6% had received two or more vaccine doses, with 41.2% experiencing CAEs. Furthermore, 73.7% had a high EUB frequency. Factors associated with CAE reporting included younger age, female sex, and high EUB frequency, while heavy alcohol use was found to be less likely to be associated with CAE reporting. Notably, a high EUB frequency was significantly associated with reported CAEs (odds ratio, 1.223; 95% confidence interval, 1.028-1.455; P = 0.023).

CONCLUSION

A nationwide online survey conducted in South Korea during the pandemic found that individuals who engaged in the relatively frequent use of electronic devices during bedtime had worse sleep quality and increased COVID-19-related adverse events compared with those using these devices less frequently. These findings have the potential to enhance our understanding of the impact of the use of electronic devices at bedtime on health.

Risk and characteristics of Bell's palsy in adults as an adverse event following COVID-19 vaccination: a retrospective study

BACKGROUND

Although an association between COVID-19 vaccination and Bell's palsy (BP) has been reported, a clear causal relationship has not been elucidated. We investigated the risk and clinical characteristics of BP after COVID-19 vaccination.

METHODS

This retrospective chart review evaluated the association between COVID-19 vaccination and BP by comparing the number of patients diagnosed with BP during the pre-COVID-19 vaccination period (March 2018-February 2021) and the COVID-19 mass vaccination period (March 2021-February 2022). We then compared vaccine-related (time between vaccination and BP onset < 42 days) and -unrelated (time interval ≥ 42 days or non-vaccination) clinical characteristics in newly diagnosed patients with BP.

RESULTS

BP occurred more during the COVID-19 vaccination period than in the previous three pre-vaccination years. Thirteen patients developed BP within 42 days of vaccination. All patients, except one, developed BP after mRNA-based vaccination, with most cases (9/13, 69.2%) occurring after the second or third dose. Thirteen patients with vaccine-related BP were younger (age 43.92 ± 13.14 vs. 54.32 ± 16.01 years; p = 0.033) and more frequently experienced taste changes (58.8% vs. 10.9%; p = 0.002) than 52 patients with vaccine-unrelated BP. Patients with vaccine-related BP had a greater likelihood of good and faster (p = 0.042) facial nerve function recovery than those with vaccine-unrelated BP (100% vs. 78%).

CONCLUSION

COVID-19 vaccines, especially mRNA-based vaccines, may be associated with BP cases with distinctive clinical characteristics, which occur more frequently in young individuals, are frequently accompanied by taste changes, and have fast and good recovery.

Multivariate Analysis of Adverse Reactions and Recipient Profiles in COVID-19 Booster Vaccinations: A Prospective Cohort Study

BACKGROUND

This study investigated the impact of vaccinated population profiles, vaccine type/interval, and the number of vaccine doses on adverse reactions to receiving a coronavirus disease 2019 (COVID-19) booster vaccination.

METHODS

A survey of adverse reactions was conducted from January 2022 to December 2022 among Osaka University Dental Hospital employees who received their third or fourth doses. The study included 194 third-dose recipients and 131 fourth-dose recipients. Comparisons of the occurrence of adverse reactions between the third- and fourth-dose groups were analyzed via a chi-squared test. The relationships between each adverse reaction occurrence and recipient profiles, vaccine type/interval, and the number of vaccine doses were analyzed via a logistic regression analysis.

RESULTS

No significant differences were found in the occurrence of adverse reactions between the third and fourth doses. Younger recipients often developed injection site reaction, fatigue, chills, fever, arthralgia, headache, diarrhea, and any adverse reactions more often. Females had higher frequencies of fatigue, chills, headache, and nausea compared to males. Recipients without underlying diseases had higher frequencies of fever and nausea than those with underlying diseases.

CONCLUSIONS

Younger recipients and females were at higher risk for adverse reactions to a COVID-19 booster vaccination, while the number of vaccinations, vaccination interval, vaccine type, and cross-vaccination showed no significant associations.

Barriers to COVID-19 vaccine surveillance: the issue of under-reporting adverse events

OBJECTIVES

This study investigated the reporting rates of adverse events following immunization (AEFIs) to the spontaneous reporting system (SRS) and its predictors among individuals with AEFIs after coronavirus disease 2019 (COVID-19) vaccination.

METHODS

A cross-sectional, web-based survey was conducted from December 2, 2021 to December 20, 2021, recruiting participants >14 days after completion of a primary COVID-19 vaccination series. Reporting rates were calculated by dividing the number of participants who reported AEFIs to the SRS by the total number of participants who experienced AEFIs. We estimated adjusted odds ratios (aORs) using multivariate logistic regression to determine factors associated with spontaneous AEFIs reporting.

RESULTS

Among 2,993 participants, 90.9% and 88.7% experienced AEFIs after the first and second vaccine doses, respectively (reporting rates, 11.6 and 12.7%). Furthermore, 3.3% and 4.2% suffered moderate to severe AEFIs, respectively (reporting rates, 50.5 and 50.0%). Spontaneous reporting was more prevalent in female (aOR, 1.54; 95% confidence interval [CI], 1.31 to 1.81); those with moderate to severe AEFIs (aOR, 5.47; 95% CI, 4.45 to 6.73), comorbidities (aOR, 1.31; 95% CI, 1.09 to 1.57), a history of severe allergic reactions (aOR, 2.02; 95% CI, 1.47 to 2.77); and those who had received mRNA-1273 (aOR, 1.25; 95% CI, 1.05 to 1.49) or ChAdOx1 (aOR, 1.62; 95% CI, 1.15 to 2.30) vaccines versus BNT162b2. Reporting was less likely in older individuals (aOR, 0.98; 95% CI, 0.98 to 0.99 per 1-year age increment).

CONCLUSIONS

Spontaneous reporting of AEFIs after COVID-19 vaccination was associated with younger age, female sex, moderate to severe AEFIs, comorbidities, history of allergic reactions, and vaccine type. AEFIs under-reporting should be considered when delivering information to the community and in public health decision-making.

Prolonged angioedema after Pfizer-BioNTech COVID-19 vaccine

This case reports a woman in her 40s with a history of allergic reaction to shellfish and iodine who presented with tongue angioedema, difficulty breathing and chest tightness after receiving the first dose of the Pfizer-BioNTech (BNT162b2) COVID-19 vaccine. Her angioedema remained for 10 days post-exposure to the vaccine, requiring 3 days of epinephrine infusion. She was discharged with advice to avoid further mRNA vaccines. This case highlights the increasing awareness needed of polyethylene glycol (PEG) allergy and the protracted nature of her reaction. A firm conclusion cannot be reached based on a single case report. More research is needed to understand whether there is a causal relationship between the BNT162b2 vaccine and PEG allergy. Awareness regarding PEG allergy and the complexities associated with it is important and needs to be raised due to its prevalent use in diverse industries.

Sex-disaggregated outcomes of adverse events after COVID-19 vaccination: A Dutch cohort study and review of the literature

Background

Albeit the need for sex-disaggregated results of adverse events after immunization (AEFIs) is gaining attention since the COVID-19 pandemic, studies with emphasis on sexual dimorphism in response to COVID-19 vaccination are relatively scarce. This prospective cohort study aimed to assess differences in the incidence and course of reported AEFIs after COVID-19 vaccination between males and females in the Netherlands and provides a summary of sex-disaggregated outcomes in published literature.

Methods

Patient reported outcomes of AEFIs over a six month period following the first vaccination with BioNTech-Pfizer, AstraZeneca, Moderna or the Johnson&Johnson vaccine were collected in a Cohort Event Monitoring study. Logistic regression was used to assess differences in incidence of 'any AEFI', local reactions and the top ten most reported AEFIs between the sexes. Effects of age, vaccine brand, comorbidities, prior COVID-19 infection and the use of antipyretic drugs were analyzed as well. Also, time-to-onset, time-to-recovery and perceived burden of AEFIs was compared between the sexes. Third, a literature review was done to retrieve sex-disaggregated outcomes of COVID-19 vaccination.

Results

The cohort included 27,540 vaccinees (38.5% males). Females showed around two-fold higher odds of having any AEFI as compared to males with most pronounced differences after the first dose and for nausea and injection site inflammation. Age was inversely associated with AEFI incidence, whereas a prior COVID-19 infection, the use of antipyretic drugs and several comorbidities were positively associated. The perceived burden of AEFIs and time-to-recovery were slightly higher in females.

Discussion

The results of this large cohort study correspond to existing evidence and contribute to the knowledge gain necessary to disentangle the magnitude of the effect sex in response to vaccination. Whilst females have a significant higher probability of experiencing an AEFI than males, we observed that the course and burden is only to a minor extent different between the sexes.

Association between COVID-19 vaccines and the menstrual cycle in young Japanese women

INTRODUCTION

Although several studies have investigated the association between coronavirus disease 2019 (COVID-19) vaccines and the menstrual cycle, available data are limited. Therefore, this study investigated the effect of COVID-19 vaccines on the menstrual cycle and the effect of the menstrual cycle phase on the vaccine side effects during vaccine administration in Japan.

METHODS

A self-administered questionnaire was used to collect data on the date of vaccination; type of vaccine; type, grade, and duration of the side effects; regularity of menstruation; normal length of the menstrual cycle; and the day one date of menstruation around vaccination. The survey was conducted from October 2021 to March 2022.

RESULTS

The difference between the predicted and actual menstrual cycle length was 1.9 ± 3.0, 1.6 ± 2.8 (p = 0.557), and 2.5 ± 3.8 (p = 0.219) days before vaccination and after the first and second dose of the vaccine, respectively. In participants who received vaccinations twice within a single menstrual cycle, this difference was 1.3 ± 3.5 and 3.9 ± 3.3 (p = 0.045) days before and after vaccination, respectively. The grade and proportion of the side effects after the second dose of the vaccine was highest during the menstrual period and lowest during the ovulation period, with a significant effect on headache and chills.

CONCLUSION

COVID-19 vaccines tended to prolong the menstrual cycle. The side effects of the COVID-19 vaccine tended to be at a maximum when vaccination occurred during the menstrual period and minimal during the ovulation period.

Psychological Distress and Physical Adverse Events of COVID-19 Vaccination among Healthcare Workers in Taiwan

The COVID-19 pandemic places high pressure on everyone, including healthcare workers (HCWs), thus causing them to experience psychological distress. HCWs have priority in receiving the COVID-19 vaccine. However, few studies have identified adverse events (AEs) and psychological distress in the HCWs group. Therefore, we investigated the association between psychological distress and AEs and the determinants of protective behaviors in Taiwanese HCWs. A longitudinal measurement was conducted among HCWs at National Cheng Kung University Hospital (NCKUH), Tainan, Taiwan (n = 483, mean age = 37.55 years). All HCWs completed an online questionnaire on psychological distress, COVID-19 vaccination AEs, and protective behaviors. We used generalized estimating equations (GEE) to analyze the correlation between psychological distress and AEs, and used multivariable logistic regressions to explore the predictors of protective behaviors. Depression and distress and anger were significantly associated with various physical AEs (p = 0.045 to p < 0.001). Suicidal thoughts became a significant independent variable of systemic AEs after COVID-19 vaccination (p = 0.014 to p < 0.001). People of older ages or females engaged more in washing their hands, wearing masks, and reducing their presence in crowded places. Suicidal thoughts were related to the occurrence of systemic AEs among HCWs. Doctors performed better at preventive behaviors compared to nurses and other HCWs. HCWs who experienced anxiety and nervousness tended to avoid crowds.

Will Omics Biotechnologies Save Us from Future Pandemics? Lessons from COVID-19 for Vaccinomics and Adversomics

The COVID-19 pandemic had cross-cutting impacts on planetary health, quotidian life, and society. Mass vaccination with the current gene-based vaccines has helped control the pandemic but unfortunately it has not shown effectiveness in preventing the spread of the virus. In addition, not all individuals respond to these vaccines, while others develop adverse reactions that cannot be neglected. It is also a fact that some individuals are more susceptible to infection while others develop effective immunization post-infection. We note here that the person-to-person and population variations in vaccine efficacy and side effects have been studied in the field of vaccinomics long before the COVID-19 pandemic. Additionally, the field of adversomics examines the mechanisms of individual differences in the side effects of health interventions. In this review, we discuss the potential of a multi-omics approach for comprehensive profiling of the benefit/risk ratios of vaccines. Vaccinomics and adversomics stand to benefit planetary health and contribute to the prevention of future pandemics in the 21st century by offering precision guidance to clinical trials as well as promoting precision use of vaccines in ways that proactively respond to individual and population differences in their efficacy and safety. This vision of pandemic prevention based on personalized instead of mass vaccination also calls for equity in access to precision vaccines and diagnostics that support a vision and practice of vaccinomics and adversomics in planetary health.

Impact of Sex and Age on mRNA COVID-19 Vaccine-Related Side Effects in Japan

mRNA COVID-19 vaccination was initiated worldwide in late 2020, and its efficacy has been well reported. However, studies about vaccine-related side effects are sparse. A total of 262 health care workers who received mRNA COVID-19 vaccine BNT162b2 were recruited, and their vaccine-related side effects were investigated. Impact of sex and age on the side effects was statistically analyzed. A higher number of vaccine-related side effects among females versus males was identified (median 3 versus 2, P < 0.05, after the first dose, and 5 versus 2.5, P < 0.01, after the second dose). General fatigue, headache, chills, and fever were the culprit adverse symptoms. In multivariate analysis, females had an increasing number of side effects after receiving their first (B = 0.7; 95% confidence interval [CI], 0.2 to 1.2) and second (B = 1.5; 95% CI, 0.7 to 2.2) vaccine doses compared to that of males. In age analysis, the older group (≥60 years old) had a lower number of side effects than the younger group (B = -0.5 with a 95% CI of -1.1 to -0.02 after the first vaccine dose, and B = -2.1 with a 95% CI of -2.9 to -1.2 after the second vaccine dose). Additionally, prolonged time to recovery was found among females (P = 0.003 after the first dose; P = 0.008 after the second dose). Specifically, symptoms of general fatigue, headache, itching, swelling at the injection site, and dizziness were the culprit symptoms affecting recovery time. Several cutaneous and membranous symptoms, including "COVID arm," were identified among females. These results highlight the impact of sex and age on side effects from mRNA COVID-19 vaccine and will aid in creating a safer vaccine. IMPORTANCE We demonstrate sex- and age-related impact on mRNA COVID-19 vaccine-related side effects, with a higher number and frequency of side effects and prolonged time to recovery in females compared to males and negative correlation between age and vaccine-related side effects. Identification of unique age- and sex-specific adverse symptoms will provide the opportunity to better understand the nature of sex- and age-associated immunological differences and develop safer and more efficacious vaccines.

Seroconversion rate after COVID-19 vaccination in patients with solid cancer: A systematic review and meta-analysis

Patients with solid cancer have an increased risk of severe coronavirus disease 2019 (COVID-19) and associated mortality than the general population. This meta-analysis aimed to investigate the currently available evidence about the efficacy of COVID-19 vaccines in patients with solid cancer. We included prospective studies comparing the immunogenicity and efficacy of COVID-19 vaccines between patients with solid cancer and healthy individuals. Relative risks of seroconversion after the first and second dose of a COVID-19 vaccine were separately pooled with the use of random effects meta-analysis. Thirty studies with 11,245 subjects met the inclusion criteria. After first vaccine dose, the pooled RR of seroconversion in patients with solid cancer vs healthy individuals was 0.54 (95% CI 0.38-0.78, I2 = 94%). After a second dose, the pooled RR of seroconversion in patients with solid cancer vs healthy controls was 0.87 (0.86-0.88, I2 = 87%). Our review suggests that, compared with healthy individuals, COVID-19 vaccines show favorable immunogenicity and efficacy in patients with solid cancer. A second dose is associated with significantly improved seroconversion, although it is slightly lower in patients with solid cancer compared with healthy individuals.

Adverse events after administration of the first and second doses of messenger RNA-based COVID-19 vaccines in Japanese subjects aged 12-18 years

OBJECTIVE

Using a prospective observational design, we assessed adverse events (AEs) after COVID-19 vaccination in Japanese patients.

METHODS

Two doses of the mRNA-1273 (SPIKEVAX®) or BNT162b2 (COMIRNATY®) vaccine were administered to participants aged 12 to 18 years, and AEs after each dose were recorded for 14 days. Data on the duration and nature (local vs. systemic) of AEs were collected using a questionnaire. Sex-based differences in AE frequency were also analyzed.

RESULTS

After the first and second doses, 152 and 135 vaccinees were enrolled, respectively. After the first dose, fever (>37.1°C) occurred in 38.9% of males and 50.0% of females, whereas local pain occurred in 89.8% and 97.7% of males and females, respectively (only SPIKEVAX® was used as the first dose). After the second dose, fever (>37.1°C) occurred in 77.8% and 82.6% of males vaccinated with COMIRNATY® and SPIKEVAX®, respectively, and 82.6% of females (all received SPIKEVAX®). The local pain rates in these groups were 80.6%, 76.3%, and 100%, respectively. After the second dose, local pain, fever (>38.1°C) and headache were significantly more common in female participants, and the median symptom duration was 3 days.

CONCLUSIONS

AEs were more frequent after the second dose and in females.

Common adverse events following immunization with the COVID-19 comirnaty vaccine (Pfizer-BioNTech) among adult population in Hanoi, Vietnam, 2021

Rationale

To prevent and control the COVID-19 pandemic, the biggest immunization campaign in history had been deployed worldwide. Therefore, it is important to inform the adverse events following immunization (AEFI) to populations.

Objectives

To prevent vaccine hesitancy, this study focused on finding the common AEFI with the COVID-19 Comirnaty vaccine (Pfizer-BioNTech) among participants aged 18 and above and related factors in Hanoi, Vietnam.

Methods

A cross-sectional study was carried out to collect participants’ data and AEFI after being vaccinated at Hanoi Medical University, Vietnam, in 2021. Logistic regression was utilized for analyzing the correlated factors of AEFI.

Results

We recruited a random sample of 820 participants who received both basic doses of Pfizer vaccine in September and October 2021. The proportion of AEFI after the first dose, second dose, and both doses of Pfizer vaccine was 24.4%, 64.2%, and 18.5%, respectively. AEFI mostly appeared within 1 day and lasted for 1 to 2 days. The AEFI were more common in females (OR=1.7; 95%CI=1.25–2.29) and younger age groups (OR=1.9; 95%CI=1.37–2.58). History of allergy, allergic diseases, chronic diseases, and occupations were not statistically significant with AEFI.

Conclusion

Our findings indicated that the COVID-19 Comirnaty vaccine is safe to be injected. Gender and age group are important factors influencing AEFI.

Young Age, Female Sex, and No Comorbidities Are Risk Factors for Adverse Reactions after the Third Dose of BNT162b2 COVID-19 Vaccine against SARS-CoV-2: A Prospective Cohort Study in Japan

Background: This study compared the adverse events (AEs) of the second and third doses of BNT162b2, as well as investigated the impact of vaccine recipients’ background and vaccination interval on the AEs of the third dose. Methods: We conducted a questionnaire survey of AEs among health care workers at Osaka University Dental Hospital. Chi-square tests were performed to compare AEs to the administration of second and third vaccine doses. Logistic regression analyses were conducted to identify factors influencing the presence of AEs using age, sex, comorbidities, and the vaccination interval. Spearman’s rank correlation coefficient was calculated to investigate the correlation between age, vaccination interval, and severity of each AE. Results: The third dose of BNT162b2 was associated with significantly more frequent or milder AEs than the second dose. Logistic regression analyses detected significant differences in six items of AEs by age, three by sex, two by comorbidities, and zero by vaccination interval. Consistently, the risk of AEs was greater among younger persons, females, and those without comorbidities. Significant negative correlations were detected between age and vaccination interval, and between age and the severity of most AEs. Conclusions: Young, female, and having no comorbidities are risk factors for AEs after the third dose of BNT162b2, while vaccination interval is not.

Adverse events after BNT162b2 mRNA COVID-19 vaccination in health care workers and medical students in Japan

To control the coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the promotion of vaccination is important. However, adverse reactions following vaccination remain a concern. To investigate adverse events in the vaccinated Japanese population, we conducted a survey-based study among health care workers, including medical doctors and nurses; other medical staff; and medical university faculty, staff, and students in a single medical school and affiliated hospital in Japan. In addition, we analyzed the association of different adverse events with individual factors (e.g., age, sex) by performing network analysis. While young age and female sex are often considered risk factors for more severe adverse events, the regression models showed neither age nor sex was associated with local injection-site reactions after the second dose in this study. In contrast to local reactions, systemic adverse events were associated with young age and female sex. However, myalgia was unique in that it was not associated with younger age even though the network analysis showed that myalgia was consistently related to arthralgia and belonged to the group of systemic events after both the first and second vaccine doses. Further study is needed to ensure safe and effective vaccination to aid in controlling the COVID-19 pandemic.