COVID-19 mRNA vaccine allergy.

PURPOSE OF REVIEW: A known history of a severe allergic reaction (e.g., anaphylaxis) to any component of the vaccine is the only contraindication to coronavirus disease 2019 (COVID-19) mRNA vaccination. It is important for pediatricians to understand the likelihood of an allergic reaction to COVID-19 mRNA vaccines, including its excipients. RECENT FINDINGS: Episodes concerning for anaphylaxis were immediately reported following early administration of COVID-19 mRNA vaccines to adults. Although allergic type symptoms were reported equally in recipients of placebos and test vaccines in phase 3 clinical trials, post-authorization prospective studies state that 0.2-2% of vaccine recipients have experienced allergic reactions. Subsequent allergy testing of affected individuals has focused largely on evaluation of allergic sensitization to a novel vaccine excipient, polyethylene glycol (PEG). PEG is a polymer incorporated in numerous pharmaceutical products because of its favorable, inert properties. The results of allergy testing in adults to date indicate that IgE mediated anaphylaxis to PEG allergy is rarely identified after COVID-19 mRNA vaccine reactions. Numerous individuals with presumed anaphylaxis have tolerated a second vaccine after evaluation and testing by an allergist, suggesting either misdiagnosis or a novel immune mechanism. SUMMARY: Confirmed anaphylactic reactions to COVID-19 mRNA vaccines are rare, likely due to a lack of preexisting IgE against the vaccine components, including PEG.

Imprecision in adverse event reports following immunization against HPV in Japan and COVID-19 in the USA, UK, and Japan-and the effects of vaccine hesitancy and government policy.

INTRODUCTION: Erroneous reports of adverse events following immunization (AEFIs) likely exacerbated the 2013 collapse of Japan's HPV immunization program. A similar phenomenon characterized the first months of COVID-19 immunization programs in the USA, UK, and Japan with high rates of reported anaphylaxis. These reports illustrate the susceptibility of supposedly objective medical judgments to public anxiety. PURPOSE AND METHODS: This study documents inaccuracies in reported AEFIs using three quantitative methods. RESULTS: One of these quantitative methods revealed that false-positive rates for anaphylaxis reports following HPV and later COVID-19 vaccination ranged from 74 to 91 percent. However, unlike HPV vaccinations in Japan, anaphylaxis reports following COVID-19 vaccines fell in Japan, the USA and the UK in the latter months of 2021. Nevertheless, false-positive rates for anaphylaxis reports remained high, suggesting a high degree of imprecision in serious AEFI reports from many countries for many vaccines. Japan's HPV immunization program indicates that media reports, patient hesitancy, healthcare providers' perspectives on vaccine safety, and consistency of government messaging, all influence report number and accuracy. A parallel publication analyzes in depth how such factors affect AEFI reports. CONCLUSION: Confidence in the safety of the COVID-19 vaccines may have been bolstered trough rapid monitoring of AEFI reports and communication of these findings. This may partly explain the different trajectories of serious AEFI following HPV immunizations in Japan and COVID-19 immunizations in the USA, UK, and Japan.

Allergic reactions to the coronavirus disease 2019 vaccine (ARCOV) study: The McGill University Health Centre experience.

BACKGROUND: Messenger RNA coronavirus disease 2019 (COVID-19) vaccines have been associated with allergic reactions. A history of anaphylaxis has been suggested as a risk factor for such reactions. Polyethylene glycol (PEG) has been proposed as a possible culprit allergen. OBJECTIVE: To investigate possible PEG or polysorbate allergy among patients reporting prior reactions to COVID-19 vaccines or PEG and to report their subsequent tolerance of COVID-19 vaccines. METHODS: From January 1, 2021, to October 31, 2021, adult patients referred to the McGill University Health Centre allergy clinics who were considered at risk of anaphylaxis were prospectively recruited. The entry criteria were any documented history of reaction to a COVID-19 vaccine or reported allergy to PEG or polysorbate. Evaluated patients underwent skin prick testing (SPT) with PEG and polysorbate. After SPT, placebo-controlled vaccine challenges were carried out. RESULTS: Of the 44 patients recruited, 40 (90.1%) had reacted to the first vaccine dose, with 18 (45%) of them had anaphylactic reaction. All patients underwent SPT and 5 (11.3%) had a positive test result. A total of 39 patients (88.6%) underwent COVID-19 vaccine challenge at the allergy clinic. Most tolerated the vaccine, with 18 (40.1%) received a single full dose, 20 (45.4%) 2 split doses, and 6 (13.6%) a graded dosing protocol. Of the 40 patients who reacted to the first dose, 2 had immediate nonsevere allergic reactions to the second dose. CONCLUSION: In this cohort of patients with a history of anaphylaxis and increased risk of allergic reactions to the COVID-19 vaccines, after allergist evaluation, including negative PEG skin testing result, the vaccine was safely administered without any serious adverse events.

[Anaphylaxis caused by vaccines]. / Anafilaxia causada por vacunas.

Even though the SARS-CoV-2 pandemic represents a historical challenge, science has had an exponential development, and the current vaccination campaigns are proof of this. Unfortunately, along came misinformation and myths regarding their production and their adverse effects. For this reason, we have considered of utter importance to review anaphylaxis, one of the most feared vaccine adverse events.Anaphylaxis can be defined as a life-threatening acute and systemic allergic reaction, with a wide clinical spectrum, which can be explained by many immunological mechanisms, and whose diagnostic complexity demands the fulfillment of strict criteria. Though infrequent, any vaccine has the potential to trigger anaphylaxis. In the United States, for the new SARS-CoV-2 vaccines, rates from 1:200 000 (Pfizer-BioNTech) to 1:360 000 doses (Moderna) have been estimated. Vaccine adverse events can be mediated by hypersensitivity reactions, either allergic or not. Unlike a typical drug allergy, rarely is the active ingredient responsible for the reaction. Therefore, excipients must be considered during the approach to this problem. Vaccine associated anaphylaxis has to be referred to an allergist so as to guarantee the maximum benefit for the patient and improve the vaccines' security profile.

A pesar de la difícil situación que se enfrenta con la actual pandemia de COVID-19, la ciencia ha tenido un desarrollo exponencial. Si bien la inmunización contra esa enfermedad ha sido posible gracias a ello, desafortunadamente se ha acompañado de desinformación y mitos en torno a su fabricación y reacciones adversas. Por tal razón, es importante revisar una de las reacciones adversas a vacunas más temidas para el personal de salud y la población general, la anafilaxia. La anafilaxia se define como una reacción alérgica aguda y sistémica que puede poner en riesgo la vida; se asocia con distintos mecanismos inmunológicos, factores desencadenantes y manifestaciones clínicas. Su diagnóstico puede ser confuso, por lo que se han establecido diferentes criterios. Todas las inmunizaciones tienen el potencial de desencadenar anafilaxia, aunque este evento es poco frecuente. Respecto de las vacunas contra el coronavirus SARS-CoV-2, en Estados Unidos se ha reportado una tasa de anafilaxia de 1:200 000 para la vacuna Pfizer-BioNTech, y de 1:360 000 para la vacuna de Moderna. Al igual que un fármaco, las vacunas pueden presentar efectos adversos mediados por mecanismos de hipersensibilidad, pero a diferencia de lo que sucede con los medicamentos, el principio activo rara vez es el responsable; es más frecuente que las reacciones indeseadas se deban a los excipientes. La sospecha de una anafilaxia secundaria a su aplicación obliga a una oportuna referencia y a un correcto diagnóstico, tanto para el beneficio del paciente como para mejorar el perfil de seguridad de la vacuna.

Anaphylaxis rates following mRNA COVID-19 vaccination in children and adolescents: Analysis of data reported to EudraVigilance.

AIM: The present study aimed to estimate the anaphylaxis rates following mRNA COVID-19 vaccination in children and adolescents in Europe. METHODS: We retrieved data on 371 anaphylaxis cases following mRNA COVID-19 vaccination in children ≤ 17 years old notified to EudraVigilance as of October 8, 2022. Overall, 27,120,512 doses of BNT162b2 vaccine and 1,400,300 doses of mRNA-1273 vaccine have been delivered to children during the study period. RESULTS: The overall mean anaphylaxis rate was 12.81 [95% confidence interval (CI): 11.49-14.12] per 106 mRNA vaccine doses [12.14 (95% CI: 6.37-17.91) per 106 doses for mRNA-1273 and 12.84 (95% CI: 11.49-14.19) per 106 doses for BNT162b2]. Children 12-17 years old accounted for 317 anaphylaxis cases, followed by 48 cases in children 3-11 years old, and 6 cases in children 0-2 years old. Children 10-17 years old had a mean anaphylaxis rate of 13.52 (95% CI: 12.03-15.00) cases per 106 mRNA vaccine doses and children 5-9 years old had a mean anaphylaxis rate of 9.51 (95% CI: 6.82-12.20) cases per 106 mRNA vaccine doses. There were two fatalities, both in the 12-17 years age group. The fatal anaphylaxis rate was 0.07 cases per 106 mRNA vaccine doses. CONCLUSIONS: Anaphylaxis is a rare adverse event after receiving an mRNA COVID-19 vaccine in children. Continuous surveillance of serious adverse events is needed to guide vaccination policies as we move towards SARS-CoV-2 endemicity. Larger real-world studies on COVID-19 vaccination in children, using clinical case confirmation, are imperative.

Anaphylaxis and Related Events Following COVID-19 Vaccination: A Systematic Review.

The coronavirus disease 2019 (COVID-19), induced by the severe acute respiratory syndrome coronavirus 2, is responsible for a global pandemic following widespread transmission and death. Several vaccines have been developed to counter this public health crisis using both novel and conventional methods. Following approval based on promising efficacy and safety data, the AstraZeneca, Janssen, Moderna, Pfizer/BioNTech, and Sinovac vaccines have been administered globally among different populations with various reported side effects. Reports of life-threatening anaphylaxis following administration were of particular concern for both health care providers and the public. A systematic literature search using PubMed, Embase, Scopus, Web of Science, Science Direct, MedRxiv, and Lens.org databases identified relevant studies reporting anaphylaxis following vaccine administration. This systematic review includes 41 studies reporting anaphylaxis. A total of 7942 cases, including 43 deaths, were reported across 14 countries. Most cases occurred following the administration of the first dose. Importantly, the benefits of vaccination outweigh the risks of anaphylaxis. Subsequently, as populations continue to get vaccinated, it is important for health care providers to be able to recognize individuals at risk of developing anaphylaxis. Furthermore, they must be familiar with both the clinical hallmarks and treatment of anaphylactic reactions to minimize long-term sequalae and prevent death in vaccinated individuals.

Incidence and Risk Factors of Immediate Hypersensitivity Reactions and Immunization Stress-Related Responses With COVID-19 mRNA Vaccine.

BACKGROUND: With the implementation of mass vaccination campaigns against COVID-19, the safety of vaccine needs to be evaluated. OBJECTIVE: We aimed to assess the incidence and risk factors for immediate hypersensitivity reactions (IHSR) and immunization stress-related responses (ISRR) with the Moderna COVID-19 vaccine. METHODS: This nested case-control study included recipients who received the Moderna vaccine at a mass vaccination center, Japan. Recipients with IHSR and ISRR were designated as cases 1 and 2, respectively. Controls 1 and 2 were selected from recipients without IHSR or ISRR and matched (1 case: 4 controls) with cases 1 and cases 2, respectively. Conditional logistic regression analysis was used to identify risk factors associated with IHSR and ISRR. RESULTS: Of the 614,151 vaccine recipients who received 1,201,688 vaccine doses, 306 recipients (cases 1) and 2478 recipients (cases 2) showed 318 events of IHSR and 2558 events of ISRR, respectively. The incidence rates per million doses were estimated as IHSR: 266 cases, ISRR: 2129 cases, anaphylaxis: 2 cases, and vasovagal syncope: 72 cases. Risk factors associated with IHSR included female, asthma, atopic dermatitis, thyroid diseases, and a history of allergy; for ISRR, the risk factors were younger age, female, asthma, thyroid diseases, mental disorders, and a history of allergy and vasovagal reflex. CONCLUSION: In the mass vaccination settings, the Moderna vaccine can be used safely owing to the low incidence rates of IHSR and anaphylaxis. However, providers should be aware of the occurrence of ISRR. Although recipients with risk factors are associated with slightly increased risks of IHSR and ISRR, this is not of sufficient magnitude to warrant special measures regarding their vaccination.

Successful mRNA COVID-19 Vaccination and Colonoscopy After Oral Desensitization in a Patient With Polyethylene Glycol Allergy.

Anaphylaxis to polyethylene glycol (PEG) is rare and mainly occurs with the use of laxatives containing PEG. Recently, an increasing number of PEG allergies have been reported, particularly those related to coronavirus disease 2019 (COVID-19) vaccines. mRNA COVID-19 vaccines, such as the BNT162b2 (Pfizer-BioNTech) and mRNA-1273 (Moderna) vaccines, contain PEG2000 as an excipient and are contraindicated when allergy to a vaccine component exist. We report a 55-year-old woman's history as a case of successful mRNA COVID-19 vaccination and colonoscopy after oral desensitization to PEG in a patient with PEG allergy who required both COVID-19 vaccination and colon evaluation. Allergy to PEG was diagnosed based on clinical history, skin test results, and basophil histamine release testing. Oral desensitization effectively suppressed histamine release from basophils in response to PEG stimulation, suggesting that oral desensitization using PEG-based laxatives may be an effective treatment option for patients with allergy to the substance.

Anaphylaxis to SARS-CoV-2 Vaccines in the Setting of a Nationwide Passive Epidemiological Surveillance Program.

BACKGROUND: Information on anaphylaxis among recipients of vaccines against the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) remains scarce. OBJECTIVE: To identify the observed incidence of anaphylaxis in recipients of different anti-SARS-CoV-2 vaccines. METHODS: A nationwide observational study among recipients of 61,414,803 doses of seven different anti-SARS-CoV-2 vaccines, describing the incidence and characteristics of adult patients (age ≥ 18 years) who developed anaphylaxis as an adverse event following immunization (AEFI) against SARS-CoV-2 vaccines between December 24, 2020, and October 15, 2021, in Mexico. RESULTS: Sixty-six patients developed anaphylaxis as an AEFI, for an overall observed incidence of 1.07 cases per 1,000,000 (95% CI 0.84-1.37) administered doses. Eighty-six percent of the patients were female, consistent with previous reports of AEFI to COVID-19 vaccines. mRNA-based vaccine recipients had the highest frequency of anaphylaxis, followed by adenovirus-vectored vaccines and inactivated virus recipients, with an observed incidence of 2.5, 0.7, and 0.2 cases per 1,000,000 doses administered, respectively. Only 46% of the patients received correct treatment with epinephrine as the first-line treatment through the appropriate route and dose. We detected one case of anaphylactic reaction-related death occurring 5 min following immunization with ChAdOx1 nCov-19 for a mortality rate of 1.5% among those who developed this AEFI. CONCLUSIONS: In our population, anaphylactic reactions were infrequent. Our study provides further evidence supporting the security of these newly developed vaccines.

Allergic Reactions After the Administration of COVID-19 Vaccines.

Background: Data on allergic reactions after the administration of coronavirus disease (COVID-19) vaccines are limited. Our aim is to analyze reports of allergic reactions after COVID-19 vaccine administration. Methods: The Vaccine Adverse Event Reporting System database was searched for reported allergic reactions after the administration of any of the COVID-19 vaccines from December 2020 to June 2021. After data mapping, the demographic and clinical characteristics of the reported cases were analyzed. Potential factors associated with anaphylaxis were evaluated using multivariable logistic regression models. Results: In total, 14,611 cases were reported. Most cases of allergic reactions comprised women (84.6%) and occurred after the first dose of the vaccine (63.6%). Patients who experienced anaphylaxis were younger (mean age 45.11 ± 5.6 vs. 47.01 ± 6.3 years, P < 0.001) and had a higher prevalence of a history of allergies, allergic rhinitis, asthma, and anaphylaxis than those who did not (P < 0.05). A history of allergies (odds ratio (OR) 1.632, 95% confidence interval (CI) 1.467-1.816, P < 0.001), asthma (OR 1.908, 95%CI 1.677-2.172, P < 0.001), and anaphylaxis (OR 7.164, 95%CI 3.504-14.646, P < 0.001) were potential risk factors for anaphylaxis. Among the 8,232 patients with reported outcomes, 16 died. Conclusions: Female predominance in allergic reaction cases after the receipt of COVID-19 vaccines was observed. Previous histories of allergies, asthma, or anaphylaxis were risk factors for anaphylaxis post-vaccination. People with these risk factors should be monitored more strictly after COVID-19 vaccination.

Background incidence rates of adverse events of special interest related to COVID-19 vaccines in Ontario, Canada, 2015 to 2020, to inform COVID-19 vaccine safety surveillance.

BACKGROUND: Background incidence rates are critical in pharmacovigilance to facilitate identification of vaccine safety signals. We estimated background incidence rates of 11 adverse events of special interest related to COVID-19 vaccines in Ontario, Canada. METHODS: We conducted a population-based retrospective observational study using linked health administrative databases for hospitalizations and emergency department visits among Ontario residents. We estimated incidence rates of Bell's palsy, idiopathic thrombocytopenia, febrile convulsions, acute disseminated encephalomyelitis, myocarditis, pericarditis, Kawasaki disease, Guillain-Barré syndrome, transverse myelitis, acute myocardial infarction, and anaphylaxis during five pre-pandemic years (2015-2019) and 2020. RESULTS: The average annual population was 14 million across all age groups with 51% female. The pre-pandemic mean annual rates per 100,000 population during 2015-2019 were 191 for acute myocardial infarction, 43.9 for idiopathic thrombocytopenia, 28.8 for anaphylaxis, 27.8 for Bell's palsy, 25.0 for febrile convulsions, 22.8 for acute disseminated encephalomyelitis, 11.3 for myocarditis/pericarditis, 8.7 for pericarditis, 2.9 for myocarditis, 2.0 for Kawasaki disease, 1.9 for Guillain-Barré syndrome, and 1.7 for transverse myelitis. Females had higher rates of acute disseminated encephalomyelitis, transverse myelitis and anaphylaxis while males had higher rates of myocarditis, pericarditis, and Guillain-Barré syndrome. Bell's palsy, acute disseminated encephalomyelitis, and Guillain-Barré syndrome increased with age. The mean rates of myocarditis and/or pericarditis increased with age up to 79 years; males had higher rates than females: from 12 to 59 years for myocarditis and ≥12 years for pericarditis. Febrile convulsions and Kawasaki disease were predominantly childhood diseases and generally decreased with age. CONCLUSIONS: Our estimated background rates will permit estimating numbers of expected events for these conditions and facilitate detection of potential safety signals following COVID-19 vaccination.

Rapid progress in our understanding of COVID-19 vaccine allergy: A cause for optimism, not hesitancy.

Anaphylaxis is a life-threatening condition and when associated with vaccination, leads to vaccine hesitancy. The concerns around vaccine-related anaphylaxis have become even more important during the coronavirus disease 2019 (COVID-19) pandemic where the COVID-19 vaccines remain one of our most important tools. Although rates of anaphylaxis to COVID-19 vaccines are not significantly different from those to other vaccines, Centers for Disease Control and Prevention guidance recommends avoidance of the same COVID-19 vaccine in individuals who had an allergic reaction or are allergic to a COVID-19 vaccine component. Fortunately, our understanding of COVID-19 vaccine allergic reactions has improved dramatically in the past year in large part due to important research efforts from individuals in the allergy community. Initially, researchers published algorithmic approaches using risk stratification and excipient skin testing. However, as our experience and knowledge improved with ongoing research, we have better data showing safety of repeat vaccination despite an initial reaction. We review our progress starting in December 2020 when the Food and Drug Administration approved the first COVID-19 vaccine in the United States through early 2022, highlighting our success in understanding COVID-19 vaccine reactions.

COVID-19 vaccination including 198 patients with history of severe anaphylactic reaction - own observations.

INTRODUCTION: The SARS-CoV-2 pandemic has taken a heavy toll of 4 million deaths. We were all looking forward to the authorisation of safe vaccines. Soon after vaccination programmes started, the reports about anaphylaxis began to emerge. Growing anxiety has urged regulatory agencies and academic societies to issue adequate recommendations regarding patient eligibility to vaccination. AIM OF THE STUDY: Observation of patients who had a history of a severe anaphylactic reaction and/or anaphylactic shock and were vaccinated against COVID-19. MATERIAL AND METHODS: A single-centre, prospective, observational study was conducted at the Department of Infectious Diseases and Paediatrics at Stefan Zeromski Specialist Hospital in Krakow, Poland. Adult patients with a history of a severe anaphylactic reaction and/or anaphylactic shock and patients without it were administered the Comirnaty vaccine by Pfizer-BioNTech or the ChAdOx1-S vaccine by AstraZeneca in a two-dose schedule at the department. The patients were then observed at the department for 60 minutes. A week after each vaccination dose, the patients were contacted by telephone in order to collect data about a late allergic reaction. RESULTS: In total, 403 patients were enrolled. For the Pfizer BioNTech Comirnaty vaccine, the study group (i.e. patients with a history of severe anaphylactic reactions to various substances, other than those present in the vaccine) included 151 patients, and there were 161 controls. For the AstraZeneca ChAdOx1-S vaccine, the study group included 47 patients, and 44 patients formed the control group. Nine cases of severe anaphylactic reactions were reported: 3 in the study groups (1.5%) and 6 in the control groups (3%). Anaphylactic shock after vaccine administration occurred in one patient from the control group. CONCLUSIONS: COVID-19 vaccination with using Pfizer-BioNTech Comirnaty and AstraZeneca ChAdOx1-S is safe also for patients with a history of a severe anaphylactic reaction and/or anaphylactic shock. Severe anaphylactic reactions and anaphylactic shock, although rare, may also develop in patients without a prior history of allergic conditions. The Personnel od vaccination centres should be therefore trained to provide medical help. Incorrect patient exclusions delay the attainment of the goal determined for the vaccination programme.

COVID-19 vaccine-related presumed allergic reactions and second dose administration by using a two-step graded protocol.

Background: Acute allergic reactions to messenger RNA (mRNA) vaccines are rare but may limit public health immunization efforts. Objectives: To characterize suspected allergic reactions to the first dose of coronavirus disease 2019 (COVID-19) mRNA vaccine and to assess the safety and utility of a two-step graded-dose protocol for the second dose of the Pfizer-BioNTech vaccine in patients with a history of low suspicion of anaphylaxis to their first dose. Methods: This was a retrospective evaluation of referrals to the allergy and immunology clinic for a presumed allergic reaction to the first dose of the COVID-19 mRNA vaccine (Pfizer-BioNTech or Moderna) between December 17, 2020, and February 28, 2021. Recommendations for the second dose and outcomes were evaluated by trained board-certified allergists. Results: Seventy-seven patients presented with a Pfizer-BioNTech reaction (56 [72.7%]) or with a Moderna reaction (21 [27.3%]). Most patients (69.7%) had symptom onset within 4 hours. Most commonly reported symptoms were cutaneous (51.9%), cardiovascular (48.1%), and respiratory (33.8%) symptoms. Recommendations included to proceed with the single dose (70.1%), two-step graded dose (19.5%), or deferral (10.4%). Twelve of 15 patients completed the second dose with a graded-dose protocol. Of these patients, five reported at least one or more similar symptoms as experienced with their first dose. Conclusion: Of the patients with presumed allergic reactions to their first dose of COVID-19 mRNA vaccine, most were able to safely receive the second dose. For those with a low suspicion of anaphylaxis, the two-step graded protocol with the Pfizer-BioNTech vaccine was well tolerated. A graded-dose protocol could be an effective strategy for second-dose vaccination in those who may otherwise defer the second dose.

Monitored COVID-19 mRNA vaccine second doses for people with adverse reactions after the first dose.

Background: After Emergency Use Authorization of the coronavirus disease 2019 (COVID-19) vaccines, guidance was provided by the Centers for Disease Control and Prevention that persons with an immediate allergic reaction to a messenger RNA (mRNA) COVID-19 vaccine should be evaluated by an allergist/immunologist before receipt of the second dose. Methods: In vaccinating health-care personnel, we referred those with significant reactions to allergy/immunology specialists so that they could safely receive the second dose. Results: We found that many reactions after the first dose were nonallergic but could be debilitating and a barrier to the second dose. We created a protocol of premedications to allow health-care personnel to safely receive their second mRNA COVID-19 vaccine dose. Conclusion: This protocol is adaptable and can be used in settings where allergy/immunology referral is not immediately available.

Analysis of COVID-19 Vaccine Type and Adverse Effects Following Vaccination.

Importance: Little is known about the factors associated with COVID-19 vaccine adverse effects in a real-world population. Objective: To evaluate factors potentially associated with participant-reported adverse effects after COVID-19 vaccination. Design, Setting, and Participants: The COVID-19 Citizen Science Study, an online cohort study, includes adults aged 18 years and older with a smartphone or internet access. Participants complete daily, weekly, and monthly surveys on health and COVID-19-related events. This analysis includes participants who provided consent between March 26, 2020, and May 19, 2021, and received at least 1 COVID-19 vaccine dose. Exposures: Participant-reported COVID-19 vaccination. Main Outcomes and Measures: Participant-reported adverse effects and adverse effect severity. Candidate factors in multivariable logistic regression models included age, sex, race, ethnicity, subjective social status, prior COVID-19 infection, medical conditions, substance use, vaccine dose, and vaccine brand. Results: The 19 586 participants had a median (IQR) age of 54 (38-66) years, and 13 420 (68.8%) were women. Allergic reaction or anaphylaxis was reported in 26 of 8680 participants (0.3%) after 1 dose of the BNT162b2 (Pfizer/BioNTech) or mRNA-1273 (Moderna) vaccine, 27 of 11 141 (0.2%) after 2 doses of the BNT162b2 or mRNA-1273 vaccine or 1 dose of the JNJ-78436735 (Johnson & Johnson) vaccine. The strongest factors associated with adverse effects were vaccine dose (2 doses of BNT162b2 or mRNA-1273 or 1 dose of JNJ-78436735 vs 1 dose of BNT162b2 or mRNA-1273; odds ratio [OR], 3.10; 95% CI, 2.89-3.34; P < .001), vaccine brand (mRNA-1273 vs BNT162b2, OR, 2.00; 95% CI, 1.86-2.15; P < .001; JNJ-78436735 vs BNT162b2: OR, 0.64; 95% CI, 0.52-0.79; P < .001), age (per 10 years: OR, 0.74; 95% CI, 0.72-0.76; P < .001), female sex (OR, 1.65; 95% CI, 1.53-1.78; P < .001), and having had COVID-19 before vaccination (OR, 2.17; 95% CI, 1.77-2.66; P < .001). Conclusions and Relevance: In this real-world cohort, serious COVID-19 vaccine adverse effects were rare and comparisons across brands could be made, revealing that full vaccination dose, vaccine brand, younger age, female sex, and having had COVID-19 before vaccination were associated with greater odds of adverse effects. Large digital cohort studies may provide a mechanism for independent postmarket surveillance of drugs and devices.

Acute unsolicited adverse events following BNT162b2 vaccine in Saudi Arabia, a real-world data.

BACKGROUND: Acute adverse events and anaphylaxis were reported after the administration of coronavirus disease (COVID-19) mRNA vaccines. We aim to explore the nature and outcome of adverse events following BNT162B2 vaccine in a community vaccination center, Riyadh, Saudi Arabia. METHOD: Within 30 min post vaccination, all acute adverse events (AAEs) that occurred before March 31st, 2021, and in people older than 16 years were reviewed (AAE group). We used the case definition of Brighton collaboration on vaccine safety to define anaphylaxis. Patients' demographics, comorbidities, allergy history, and outcome at disposition were collected. Observation duration after vaccination was short (<15 min) or extended (<3 h). Statistical analysis was performed to study AAEs association with the study variables and outcomes. RESULTS: Out of 71,221 vaccine recipients, 144 (0.002%) had developed 345 AAEs, at a rate of 48.4 events per 10,000 dose administered. The majority of cases in AAE group were first dose recipients (93.8%) and previously healthy (59%), while the minority had a previous history of allergy (6.3%) or a laboratory-confirmed COVID-19 (4.2%). We found a significant association between female gender and the occurrence of any AAE (p-value = 0.002). Per every 10,000 doses administered, non-anaphylactic AAEs were dizziness (17.8), headache (9.7), nausea (7.1), or syncope (3.2). Only one in every ten AAEs was considered serious and resulted in an extended observation (4.8 per 10,000 doses), but only 1/144 required hospitalization for non-anaphylaxis reasons (0.1 per 10,000 doses). According to the Brighton collaboration definition of anaphylaxis, no single case of high certainty anaphylaxis was recorded. No death was documented in this cohort. CONCLUSION: Acute adverse events due toBNT162b2 vaccinewere rare andmostlynon-seriouswith a tendency to occur more in women. Further prospectivestudieson largervaccine recipientsto evaluatethe incidenceof anaphylaxis in the Saudi population are warranted.

Anaphylaxis rates associated with COVID-19 vaccines are comparable to those of other vaccines.

We retrieved data on 8940 anaphylaxis cases post-COVID-19 vaccination from the US Vaccine Adverse Event Reporting System and the European EudraVigilance from week 52/2020 through week 31/2021 and compared them with those of other vaccines. Overall, 837,830,000 COVID-19 vaccine doses were delivered in the US and Europe during the study period, for which the vaccine name was known. The mean anaphylaxis rate was estimated at 10.67 cases per 106 doses of COVID-19 vaccines (range: 7.99-19.39 cases per 106 doses depending on the vaccine). COVID-19 vaccines ranked fifth in reported anaphylaxis rates, behind rabies, tick-borne encephalitis, measles-mumps-rubella-varicella, and human papillomavirus vaccines (70.77, 20, 19.8, and 13.65 cases per 106 vaccine doses, respectively). COVID-19 vaccines are within the range of anaphylaxis rates reported across several common vaccines in these two passive reporting systems. These data should be communicated to reassure the general population about the safety profile of COVID-19 vaccines.