Surveillance for Guillain-Barré syndrome after influenza vaccination among U.S. Medicare beneficiaries during the 2017-2018 season

Surveillance of COVID-19 vaccine safety among elderly persons aged 65 years and older

BACKGROUND

Monitoring safety outcomes following COVID-19 vaccination is critical for understanding vaccine safety especially when used in key populations such as elderly persons age 65 years and older who can benefit greatly from vaccination. We present new findings from a nationally representative early warning system that may expand the safety knowledge base to further public trust and inform decision making on vaccine safety by government agencies, healthcare providers, interested stakeholders, and the public.

METHODS

We evaluated 14 outcomes of interest following COVID-19 vaccination using the US Centers for Medicare & Medicaid Services (CMS) data covering 30,712,101 elderly persons. The CMS data from December 11, 2020 through Jan 15, 2022 included 17,411,342 COVID-19 vaccinees who received a total of 34,639,937 doses. We conducted weekly sequential testing and generated rate ratios (RR) of observed outcome rates compared to historical (or expected) rates prior to COVID-19 vaccination.

FINDINGS

Four outcomes met the threshold for a statistical signal following BNT162b2 vaccination including pulmonary embolism (PE; RR = 1.54), acute myocardial infarction (AMI; RR = 1.42), disseminated intravascular coagulation (DIC; RR = 1.91), and immune thrombocytopenia (ITP; RR = 1.44). After further evaluation, only the RR for PE still met the statistical threshold for a signal; however, the RRs for AMI, DIC, and ITP no longer did. No statistical signals were identified following vaccination with either the mRNA-1273 or Ad26 COV2.S vaccines.

INTERPRETATION

This early warning system is the first to identify temporal associations for PE, AMI, DIC, and ITP following BNT162b2 vaccination in the elderly. Because an early warning system does not prove that the vaccines cause these outcomes, more robust epidemiologic studies with adjustment for confounding, including age and nursing home residency, are underway to further evaluate these signals. FDA strongly believes the potential benefits of COVID-19 vaccination outweigh the potential risks of COVID-19 infection.

Environmental factors influencing the risk of ANCA-associated vasculitis

Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is a group of diseases characterized by inflammation and destruction of small and medium-sized blood vessels. Clinical disease phenotypes include microscopic polyangiitis (MPA), granulomatosis with polyangiitis (GPA), and eosinophilic granulomatosis with polyangiitis (EGPA). The incidence of AAV has been on the rise in recent years with advances in ANCA testing. The etiology and pathogenesis of AAV are multifactorial and influenced by both genetic and environmental factors, as well as innate and adaptive immune system responses. Multiple case reports have shown that sustained exposure to silica in an occupational environment resulted in a significantly increased risk of ANCA positivity. A meta-analysis involving six case-control studies showed that silica exposure was positively associated with AAV incidence. Additionally, exposure to air pollutants, such as carbon monoxide (CO), is a risk factor for AAV. AAV has seasonal trends. Studies have shown that various environmental factors stimulate the body to activate neutrophils and expose their own antigens, resulting in the release of proteases and neutrophil extracellular traps, which damage vascular endothelial cells. Additionally, the activation of complement replacement pathways may exacerbate vascular inflammation. However, the role of environmental factors in the etiology of AAV remains unclear and has received little attention. In this review, we summarized the recent literature on the study of environmental factors, such as seasons, air pollution, latitude, silica, and microbial infection, in AAV with the aim of exploring the relationship between environmental factors and AAV and possible mechanisms of action to provide a scientific basis for the prevention and treatment of AAV.

Guillain-Barre syndrome following COVID-19 vaccination: a case report and an updated review

Background

Coronavirus disease-2019 (COVID-19) has caused a pandemic that has recently affected every aspect of life. Fortunately, many vaccines with high safety and efficacy profiles were developed timely to face this pandemic. In a very short time, billions of people were vaccinated. In the meantime, a wide range of neurological syndromes are being reported. Guillain-Barré syndrome (GBS) which is a rare immune-mediated post-infectious peripheral neuropathy was reported after both the COVID-19 infection itself and many types of its vaccines.

Methods

We are reporting a case of post-AstraZeneca vaccine GBS and reviewing the literature of all reported post-COVID-19 vaccines GBS till July 2021.

Results

29 adult patients were reported. Of them 58.6% were males. Their mean age is 58.2 years. The median time to clinical onset after vaccine administration was 13.2 days. 86.2% of patients had their symptoms following immunization with the 1^st dose of AstraZeneca vector-based covid vaccine. Facial palsy was the most predominant single symptom in 75.8% of patients.

Conclusion

Guillain-Barré syndrome is a well-recognized but still rare adverse event following vaccination against COVID-19. Although preliminary data incriminates viral vector-based vaccines more than the other types, active post-vaccination surveillance and more powerful statistics are mandatory to reach a solid conclusion regarding the presence of a causal relation.

Risk of Guillain-Barré Syndrome Following Recombinant Zoster Vaccine in Medicare Beneficiaries

IMPORTANCE

Guillain-Barré syndrome can be reported after vaccination. This study assesses the risk of Guillain-Barré syndrome after administration of recombinant zoster vaccine (RZV or Shingrix), which is administered in 2 doses 2 to 6 months apart.

OBJECTIVE

Use Medicare claims data to evaluate risk of developing Guillain-Barré syndrome following vaccination with zoster vaccine.

DESIGN, SETTING, AND PARTICIPANTS

This case series cohort study included 849 397 RZV-vaccinated and 1 817 099 zoster vaccine live (ZVL or Zostavax)-vaccinated beneficiaries aged 65 years or older. Self-controlled analyses included events identified from 2 113 758 eligible RZV-vaccinated beneficiaries 65 years or older. We compared the relative risk of Guillain-Barré syndrome after RZV vs ZVL, followed by claims-based and medical record-based self-controlled case series analyses to assess risk of Guillain-Barré syndrome during a postvaccination risk window (days 1-42) compared with a control window (days 43-183). In self-controlled analyses, RZV vaccinees were observed from October 1, 2017, to February 29, 2020. Patients were identified in the inpatient, outpatient procedural (including emergency department), and office settings using Medicare administrative data.

EXPOSURES

Vaccination with RZV or ZVL vaccines.

MAIN OUTCOMES AND MEASURES

Guillain-Barré syndrome was identified in Medicare administrative claims data, and cases were assessed through medical record review using the Brighton Collaboration case definition.

RESULTS

Amongst those who received RZV vaccinees, the mean age was 74.8 years at first dose, and 58% were women, whereas among those who received the ZVL vaccine, the mean age was 74.3 years, and 60% were women. In the cohort analysis we detected an increase in risk of Guillain-Barré syndrome among RZV vaccinees compared with ZVL vaccinees (rate ratio [RR], 2.34; 95% CI, 1.01-5.41; P = .047). In the self-controlled analyses, we observed 24 and 20 cases during the risk and control period, respectively. Our claims-based analysis identified an increased risk in the risk window compared with the control window (RR, 2.84; 95% CI, 1.53-5.27; P = .001), with an attributable risk of 3 per million RZV doses (95% CI, 0.62-5.64). Our medical record-based analysis confirmed this increased risk (RR, 4.96; 95% CI, 1.43-17.27; P = .01).

CONCLUSIONS AND RELEVANCE

Findings of this case series cohort study indicate a slightly increased risk of Guillain-Barré syndrome during the 42 days following RZV vaccination in the Medicare population, with approximately 3 excess Guillain-Barré syndrome cases per million vaccinations. Clinicians and patients should be aware of this risk, while considering the benefit of decreasing the risk of herpes zoster and its complications through an efficacious vaccine, as risk-benefit balance remains in favor of vaccination.

Safety of vaccines used for routine immunization in the United States: An updated systematic review and meta-analysis

BACKGROUND

Understanding the safety of vaccines is critical to inform decisions about vaccination. Our objective was to conduct a systematic review of the safety of vaccines recommended for children, adults, and pregnant women in the United States.

METHODS

We searched the literature in November 2020 to update a 2014 Agency for Healthcare Research and Quality review by integrating newly available data. Studies of vaccines that used a comparator and reported the presence or absence of key adverse events were eligible. Adhering to Evidence-based Practice Center methodology, we assessed the strength of evidence (SoE) for all evidence statements. The systematic review is registered in PROSPERO (CRD42020180089).

RESULTS

Of 56,603 reviewed citations, 338 studies reported in 518 publications met inclusion criteria. For children, SoE was high for no increased risk of autism following measles, mumps, and rubella (MMR) vaccine. SoE was high for increased risk of febrile seizures with MMR. There was no evidence of increased risk of  intussusception with rotavirus vaccine at the latest follow-up (moderate SoE), nor of diabetes (high SoE). There was no evidence of increased risk or insufficient evidence for key adverse events for newer vaccines such as 9-valent human papillomavirus and meningococcal B vaccines. For adults, there was no evidence of increased risk (varied SoE) or insufficient evidence for key adverse events for the new adjuvanted inactivated influenza vaccine and recombinant adjuvanted zoster vaccine. We found no evidence of increased risk (varied SoE) for key adverse events among pregnant women following tetanus, diphtheria, and acellular pertussis vaccine, including stillbirth (moderate SoE).

CONCLUSIONS

Across a large body of research we found few associations of vaccines and serious key adverse events; however, rare events are challenging to study. Any adverse events should be weighed against the protective benefits that vaccines provide.

Postmarketing safety surveillance of quadrivalent recombinant influenza vaccine: Reports to the vaccine adverse event reporting system

On October 7, 2016, the Food and Drug Administration approved recombinant hemagglutinin quadrivalent influenza vaccine (RIV4) (Spodoptera frugiperda cell line; Flublok Quadrivalent) for active immunization for the prevention of influenza disease in individuals 18 years of age and older. Clinical trials did not reveal any major differences in adverse events or serious adverse events following Flublok Quadrivalent versus standard-dose quadrivalent inactivated influenza vaccine. To improve our understanding of the safety profile of this vaccine, we reviewed and summarized adverse event reports after Flublok Quadrivalent administration to the Vaccine Adverse Event Reporting System (VAERS). Through June 30, 2020, VAERS received 849 reports after RIV4 vaccination. The vast majority (810; 95%) were non-serious. Among serious events, there were 10 cases of Guillain-Barré syndrome, including 5 people who required mechanical ventilation and 2 people who died. Many allergic reactions were reported as non-serious, but required interventions to treat a life-threatening event, e.g., epinephrine, nebulizers, albuterol, glucocorticoids, and supplemental oxygen. Two people experienced a positive rechallenge (i.e., allergic reactions after repeated vaccination with RIV4), including a person who-despite premedication with antihistamines-developed respiratory difficulties, required epinephrine, and was transported to the emergency department. The occurrence of anaphylaxis and other allergic reactions in some individuals may reflect an underlying predisposition to atopy that may manifest itself after an exposure to any drug or vaccine, and does not necessarily suggest that Flublok Quadrivalent is particularly allergenic. Postmarketing safety surveillance will continue to be vital for understanding the benefits and risks of quadrivalent recombinant influenza vaccine.

Introductory paper: High-dose influenza vaccine

Seasonal influenza has a significant impact on global public health each year, especially in older adults 65 years of age and above. This paper presents the evolution of high-dose influenza vaccine and the quantity as well as quality of evidence on this vaccine. Its introduces other peer-reviewed manuscripts included in this supplement covering the benefits high-dose influenza vaccine over ten consecutive influenza seasons. The development of the high-dose influenza vaccine represents an important step in the evolution of influenza vaccines, offering an advancement in prevention of influenza and a step in encouraging healthy aging in older adults. A video summary of the article can be accessed via the Supplementary data link at the end of this article.

Guillain-Barré Syndrome After High-Dose Influenza Vaccine Administration in the United States, 2018-2019 Season

BACKGROUND

The Vaccine Safety Datalink (VSD) identified a statistical signal for an increased risk of Guillain-Barré syndrome (GBS) in days 1-42 after 2018-2019 high-dose influenza vaccine (IIV3-HD) administration. We evaluated the signal using Medicare.

METHODS

We conducted early- and end-of-season claims-based self-controlled risk interval analyses among Medicare beneficiaries ages ≥65 years, using days 8-21 and 1-42 postvaccination as risk windows and days 43-84 as control window. The VSD conducted chart-confirmed analyses.

RESULTS

Among 7 453 690 IIV3-HD vaccinations, we did not detect a statistically significant increased GBS risk for either the 8- to 21-day (odds ratio [OR], 1.85; 95% confidence interval [CI], 0.99-3.44) or 1- to 42-day (OR, 1.31; 95% CI, 0.78-2.18) risk windows. The findings from the end-of-season analyses were fully consistent with the early-season analyses for both the 8- to 21-day (OR, 1.64; 95% CI, 0.92-2.91) and 1- to 42-day (OR, 1.12; 95% CI, 0.70-1.79) risk windows. The VSD's chart-confirmed analysis, involving 646 996 IIV3-HD vaccinations, with 1 case each in the risk and control windows, yielded a relative risk of 1.00 (95% CI, 0.06-15.99).

CONCLUSIONS

The Medicare analyses did not exclude an association between IIV3-HD and GBS, but it determined that, if such a risk existed, it was similar in magnitude to prior seasons. Chart-confirmed VSD results did not confirm an increased risk of GBS.

Antigenic Variability a Potential Factor in Assessing Relationship Between Guillain Barré Syndrome and Influenza Vaccine - Up to Date Literature Review

Guillain-Barré syndrome (GBS) is a possible serious adverse event of the influenza vaccine but it is yet to be proven. The objective of our traditional literature review is to assess the potential relationship between GBS and influenza vaccine. A traditional literature review has been carried out by selecting 26 articles from PubMed published between 2011 and 2020. Twenty-six articles met the selection criteria (eight observational studies, four systematic literature review, three meta-analyses, two case-control, two retrospective cohort, and seven case series). Selected studies were focused on monitoring the safety of influenza vaccines, the relative safety of pandemic and seasonal influenza vaccines, influenza vaccine a potential etiology of GBS, and pathogenesis of post-vaccination GBS. Few studies have shown a higher incidence of GBS with a pandemic influenza vaccine compared to the seasonal influenza vaccine, while several studies have concluded a small increase in the possibility of GBS following any type of influenza vaccine. There were some studies that estimated no association possibly due to the presence of confounding factors such as influenza-like illness, low power of the study, and reporting bias in post-vaccination surveillance programs. GSB should be taken into consideration as one of the less common but serious side effects of the influenza vaccine but it should not adversely affect the acceptance of the influenza vaccination program. Continuous monitoring of influenza vaccine safety should be performed regularly.

Establishing and Maintaining a Vaccine-Positive Practice Culture

A vaccine-positive practice culture encourages immunization against vaccine-preventable diseases by supporting policies and practices that reduce barriers and improve efficacy for vaccine delivery. Key components of a vaccine-positive practice include a well-trained, knowledgeable, collaborative health care practice team; access to immunizations in the practice; and a vaccine practice champion. Leveraging these encourages a provaccine environment and fosters productive dialogue, even among vaccine-hesitant patients/parents.

Safety review of tetanus toxoid, reduced diphtheria toxoid, acellular pertussis vaccines (Tdap) in adults aged ≥65 years, Vaccine Adverse Event reporting System (VAERS), United States, September 2010-December 2018

INTRODUCTION

The Advisory Committee on Immunization Practices (ACIP) recommends vaccination with tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis vaccine (Tdap) in persons ≥65 years of age. To date, few studies have assessed the safety of Tdap in this population. We aimed to summarize reports submitted to the Vaccine Adverse Event Reporting System (VAERS) following receipt of Tdap in this age group.

METHODS

We searched for and analyzed U.S. VAERS reports of Tdap among individuals ≥65 years of age submitted from September 1, 2010 through December 31, 2018. We classified reports according to concurrent vaccination, seriousness, and outcome (death, non-death) and determined the frequency of reported adverse events (AEs). For serious reports, we reviewed available medical records. Data mining analyses were undertaken to detect disproportionality in reporting.

RESULTS

VAERS received a total of 1,798 reports following Tdap, of which 104 (6%) were serious. The most common AEs were injection site erythema (26%; n = 468), injection site pain (19%; n = 335), injection site swelling (18%; n = 329), and erythema (18%; n = 321). We identified seven deaths; none were attributed to Tdap. Among serious non-death reports, nervous system disorders (35.1%; n = 34) and infections and infestations (n = 18.6%; n = 18) were most commonly reported. Data mining did not identify any vaccine-AE combination reported more frequently than expected.

CONCLUSIONS

We did not identify any new safety concern over nearly a decade of recommended Tdap use among adults ≥65 years of age. Findings from this post-marketing review are consistent with prior post-marketing observations and pre-licensure studies.

Surveillance for Guillain-Barré syndrome after 2015-2016 and 2016-2017 influenza vaccination of Medicare beneficiaries

BACKGROUND

Guillain-Barré syndrome (GBS) is a serious acute demyelinating disease, an increased risk of which was found after the 1976 swine flu vaccinations. The U.S. Food and Drug Administration, in collaboration with the Centers for Medicare & Medicaid Services, has been conducting active surveillance for GBS after influenza vaccinations of Medicare Fee-For-Service beneficiaries since 2009.

METHODS

We conducted active surveillance for GBS claims in the 2015-2016 and 2016-2017 influenza seasons using the Updating Sequential Probability Ratio Test (USPRT) to monitor for signals of GBS risk. We performed self-controlled risk interval (SCRI) analyses at the end of both seasons, including chart confirmation in the 2015-2016 season, to estimate the odds ratio of GBS risk. We used 1-42 and 8-21 days post-vaccination as primary and secondary risk windows, respectively, and 43-84 days post-vaccination as the control window.

RESULTS

Over 13 million beneficiaries were vaccinated in each season. USPRT found a low magnitude signal for GBS in both seasons. SCRI analyses did not find excess GBS risk following any influenza vaccine for days 1-42 post-vaccination in either season. In the 2015-2016 season, for the 8-21 day window, our chart-confirmation showed an attributable GBS risk of 0.87 (95% CI: 0.16, 1.49) and 1.68 (95% CI: 0.69, 2.41) cases per million vaccinees after all seasonal and high dose (HD) vaccines, respectively, an elevated GBS risk for beneficiaries aged ≥75 years following all seasonal vaccines (OR: 2.25; 95% CI: 1.15, 4.39) and HD vaccine (OR: 3.67, 95% CI: 1.52, 8.85), and an elevated GBS risk for males who received seasonal vaccines (OR: 2.18; 95% CI: 1.15, 4.15) and HD vaccine (OR: 3.33; 95% CI: 1.35, 8.20). The finding of elevated GBS risk with advancing age and in males is consistent with literature; however, a distinction between HD and SD was a new finding. In the 2016-17 season, for the 8-21 day window, attributed cases showed an attributable GBS risk of 0.87 (95% CI: 0.03, 1.61) and 1.11 (95% CI: 0.00, 2.01) cases per million vaccinees after all seasonal and HD vaccines, respectively. We found no excess GBS risk for standard dose vaccines in the 8-21 day window in either season.

CONCLUSIONS

Our primary analysis finding of no excess GBS risk during both seasons was reassuring. The slightly elevated GBS risk, although in the expected range, in the 8-21 day window after all seasonal and high dose vaccines, but not after standard dose vaccines is hypothesis-generating because the difference may be due to vaccine factors such as antigen amount or strains in various seasons or due to host factors.