Thrombocytopenia after vaccination: Case reports to the US Vaccine Adverse Event Reporting System, 1990–2008

Safety of Immunization for Children with Immune Thrombocytopenia

Vaccine hesitancy is a common issue for children with immune thrombocytopenia (ITP) in China. The objective of this paper is to assess the immunization statuses of children with ITP, analyze the possible relationship between immunization and thrombocytopenia, and evaluate the safety of immunization after ITP remission. We included 186 children with an ITP history and followed up with them for two years after receiving re-immunization recommendations. The participants had an overall age-appropriate vaccine coverage of 57.9%. Vaccine-associated thrombocytopenia occurred in 99 (53.2%, 95% CI = 46.06-60.26) children ranging from 0 to 34 days following immunization, with 14 vaccines involved. One hundred and fifty-four (82.3%, 95% CI = 76.72-87.54) children were advised to restart immunization, whereas 32 (17.2%, 95% CI = 12.46-23.28) were advised to postpone partial or full vaccination. Following the follow-up, 150 (80.6%, 95% CI = 74.37-85.68) children completed the catch-up immunization, whereas 27 (14.5%, 95% CI = 10.17-20.30) partially completed it. Four patients with thrombocytopenia relapsed following the re-immunization. Incomplete catch-up immunization was related to the factors of chronic thrombocytopenia, vaccine-associated thrombocytopenia, and the relapse of ITP following re-immunization. ITP may occur after immunization with vaccines other than measles-containing vaccines. Re-immunization in children with ITP generally does not result in a relapse, regardless of whether the previous thrombocytopenia was vaccine-associated.

Immune thrombocytopenic purpura after influenza vaccine administration; a systematic review and meta-analysis

BACKGROUND

The American Society of Haematology defines immune thrombocytopenic purpura (ITP) as a common hematologic disorder characterized by a transient or long-term decrease in platelet counts (< 100 × 109/L.), purpura, and haemorrhagic episodes caused by antiplatelet autoantibodies, with the exclusion of other clinical conditions. We aimed to systematically determine the incidence of ITP in adults and children following influenza vaccination, the duration between vaccination and the occurrence of ITP, and to identify predictors of ITP after the vaccine.

METHODS

We searched PubMed, Cochrane Library, Google Scholar, Web of Science, Scopus, and Science Direct. We included primary studies that assessed the occurrence of immune thrombocytopenia in individuals who had received any influenza vaccine (primary or booster dose), regardless of the dosage, preparation, time of administration, or age of the participants. We excluded studies that were (a) Narrative, scoping, and umbrella reviews ;(b) studies with no accessible full text, abstract-only studies, or (c) Overlapping or unreliable data. The risk of bias in the included studies was assessed using the Joanna Briggs Institute (JBI) tool. We categorized studies for qualitative analysis based on study design. Descriptive statistics were used to summarize quantitative data, including the incidence of ITP after influenza vaccination.

RESULTS

Out of 729 articles retrieved from the database search, we included 24 studies. All patients identified and included in this systematic review presented with immune thrombocytopenia, determined by their platelet count. The period between vaccination and the occurrence of ITP ranged from (2:35 days). The mean duration was 13.5 days. The analysis revealed a statistically significant incidence rate ratio (IRR) = 1.85,95% CI [1.03-3.32] of ITP occurrence after 42 days.

CONCLUSIONS

Influenza-associated ITP is uncommon, self-limiting, non-life-threatening, and curable. None of the patients reported having severe adverse events or death. Further studies are required to confirm the exact incidence of the ITP to better understand the pathophysiology of ITP development post-influenza vaccination.

Rare Heterogeneous Adverse Events Associated with mRNA-Based COVID-19 Vaccines: A Systematic Review

Background: Since the successful development, approval, and administration of vaccines against SARS-CoV-2, the causative agent of COVID-19, there have been reports in the published literature, passive surveillance systems, and other pharmacovigilance platforms of a broad spectrum of adverse events following COVID-19 vaccination. A comprehensive review of the more serious adverse events associated with the Pfizer-BioNTech and Moderna mRNA vaccines is warranted, given the massive number of vaccine doses administered worldwide and the novel mechanism of action of these mRNA vaccines in the healthcare industry. Methods: A systematic review of the literature was conducted to identify relevant studies that have reported mRNA COVID-19 vaccine-related adverse events. Results: Serious and severe adverse events following mRNA COVID-19 vaccinations are rare. While a definitive causal relationship was not established in most cases, important adverse events associated with post-vaccination included rare and non-fatal myocarditis and pericarditis in younger vaccine recipients, thrombocytopenia, neurological effects such as seizures and orofacial events, skin reactions, and allergic hypersensitivities. Conclusions: As a relatively new set of vaccines already administered to billions of people, COVID-19 mRNA-based vaccines are generally safe and efficacious. Further studies on long-term adverse events and other unpredictable reactions in close proximity to mRNA vaccination are required.

COVID-19 mRNA vaccine-associated encephalopathy, myocarditis, and thrombocytopenia with excellent response to methylprednisolone: A case report

INTRODUCTION

Large-scale vaccination is considered one of the most effective strategies to control the pandemic of COVID-19. Since its start, different complications have been described thought to be related to vaccination. Here, we present a rare case where encephalopathy, myocarditis, and thrombocytopenia developed simultaneously following the second dose of Pfizer-BioNTech mRNA vaccine (BNT162b2).

CASE PRESENTATION

A 15-years-old female presented with fever, altered consciousness, and convulsions after taking the second shot of the vaccine. Clinical and laboratory workup was notable for the presence of thrombocytopenia and myocarditis. No alternative causes of encephalitis were found. The patient responded significantly to methylprednisolone suggesting underlying immune pathogenesis responsible for the clinical features. The diagnostic criteria for possible autoimmune encephalitis were also fulfilled.

CONCLUSION

Although rare, the clinician should be aware of the possible adverse events following COVID-19 vaccination. Further research with large pooled data is needed to get more insight into its pathogenesis and causal relationship.

Thrombosis and thrombocytopenia in COVID-19 and after COVID-19 vaccination

Thrombosis that occurs in coronavirus disease 19 (COVID-19) is a serious complication and a critical aspect of pathogenesis in the disease progression. Although thrombocytopenia is uncommon in the initial presentation, it may also reflect disease severity due to the ability of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) to activate platelets. This occurs directly through the spike protein-angiotensin converting enzyme 2 (ACE2) interaction and indirectly by coagulation and inflammation activation. Dysregulation in both innate and adaptive immune systems is another critical factor that causes thrombosis and thrombocytopenia in COVID-19.

Vaccination is the most potent and effective tool to mitigate COVID-19; however, rare side effects, namely vaccine-induced immune thrombotic thrombocytopenia (VITT)/thrombosis with thrombocytopenia syndrome (TTS) can occur following adenovirus-vectored vaccine administration. VITT/TTS is rare, and thrombocytopenia can be the clue to detect this serious complication. It is important to consider that thrombocytopenia and/or thromboembolism are not events limited to post-vaccination with vectored vaccine, but are also seen rarely after vaccination with other vaccines.

Various conditions mimic VITT/TTS, and it is vital to achieving the correct diagnosis at an earlier stage. Antiplatelet factor 4 (PF4) antibody detection by the enzyme-linked immunosorbent assay (ELISA) is used for diagnosing VITT/TTS. However, false-positive rates also occur in vaccinated people, who do not show any thrombosis or thrombocytopenia. Vaccinated people with messenger RNA vaccine can show positive but low density and non-functional in terms of platelet aggregation, it is vital to check the optical density. If anti-PF4 ELISA is not available, discriminating other conditions such as antiphospholipid syndrome, thrombotic thrombocytopenic purpura, immune thrombocytopenic purpura, systemic lupus erythematosus, and hemophagocytic syndrome/hemophagocytic lymphohistiocytosis is critical when the patients show thrombosis with thrombocytopenia after COVID-19 vaccination.

Immune Thrombocytopenic Purpura Following Pfizer-BioNTech COVID-19 Vaccine in an Elderly Female

Mass vaccination campaigns are being run all over the globe to combat the ongoing COVID-19 pandemic. There have been several reports of immune thrombocytopenic purpura (ITP) occurrence following COVID-19 vaccination. However, ITP due to the Pfizer-BioNTech vaccine has been rarely reported, and a causal link has not been identified. The pathophysiology behind immune thrombocytopenia is similar to heparin-induced thrombocytopenia. The management is also similar to other secondary immune thrombocytopenia. We present a case of a 67-year old female diagnosed with immune thrombocytopenia following Pfizer-BioNTech vaccination. The treatment was resistant to high-dose steroids, intravenous immunoglobulin (IVIG), and rituximab and eventually responded to a thrombopoietin-stimulating agent.

Thrombocytopenia including immune thrombocytopenia after receipt of mRNA COVID-19 vaccines reported to the Vaccine Adverse Event Reporting System (VAERS)

Background

The objective of this study is to assess cases of thrombocytopenia, including immune thrombocytopenia (ITP), reported to the Vaccine Adverse Event Reporting System (VAERS) following vaccination with mRNA COVID-19 vaccines.

Methods

This case-series study analyzed VAERS reports of thrombocytopenia after vaccination with Pfizer-BioNTech COVID-19 Vaccine or Moderna COVID-19 Vaccine.

Results

Fifteen cases of thrombocytopenia were identified among 18,841,309 doses of Pfizer-BioNTech COVID-19 Vaccine and 13 cases among 16,260,102 doses of Moderna COVID-19 Vaccine. The reporting rate of thrombocytopenia was 0.80 per million doses for both vaccines. Based on an annual incidence rate of 3.3 ITP cases per 100,000 adults, the observed number of all thrombocytopenia cases, which includes ITP, following administration of mRNA COVID-19 vaccines is not greater than the number of ITP cases expected.

Conclusions

The number of thrombocytopenia cases reported to VAERS does not suggest a safety concern attributable to mRNA COVID-19 vaccines at this time.

Safety of pentavalent DTaP-IPV/Hib combination vaccine in post-marketing surveillance in Guangzhou, China, from 2011 to 2017

BACKGROUND

The DTaP-IPV/Hib combination vaccine can replace the acellular tetanus vaccine, polio vaccine, and the Haemophilus influenzae type B vaccine. Data on the safety of DTaP-IPV/Hib vaccines are required. We aimed to evaluate the safety of the vaccination program.

METHODS

Using the National Adverse Events Following Immunization (AEFI) surveillance system (CNAEFIS) in Guangzhou, China, a retrospective study was performed from May 11, 2011, to December 31, 2017. There were 376 cases of adverse events after vaccination with the DTaP IPV/Hib vaccine. The primary analysis indicators were the number of vaccines used, the number of AEFI reports received, and the reporting rate (per 100,000).

RESULTS

From May 1, 2011, to December 31, 2017, 516,000 doses of vaccine were inoculated, and 376 cases of adverse reactions were reported; the reporting rate was 72.8 per 100,000 vaccines. There were eight cases of serious AEFIs (1.5 per 100,000), with four cases of thrombocytopenic purpura (0.8 per 100,000); three cases of cyanosis of the lips, stiffness, and flexion of limbs, and convulsions (0.6 per 100,000); and one case of a high fever (0.2 per 100,000). The highest incidence of AEFIs occurred after the fourth dose (n = 207, 55.0%, 40.1 per 100,000), followed by the first dose (n = 81, 21.5%, 15.7 per 100,000), second dose (n = 48, 12.8%, 9.3 per 100,000) and third dose (n = 40, 10.6%, 7.7 per 100,000). The AEFI incidence was higher after injection of the vaccine into the deltoid muscle of the upper arm (n = 276, 73.4%, 53.5 per 100,000) than after injection of the vaccine into the thigh (n = 100, 26.6%, 19.4 per 100,000). There was a significant difference between AEFIs after injection into the deltoid of the upper arm deltoid and the thigh (x² = 164.8, P < 0.05).

CONCLUSIONS

Most of the reported AEFIs after DTaP-IPV/Hib vaccination are not serious. There were four cases of TP in this study; vaccination may be a rare cause of thrombocytopenic purpura.

Immune thrombocytopenic purpura risk by live, inactivated and simultaneous vaccinations among Japanese adults, children and infants: a matched case-control study

This case–control study investigated immune thrombocytopenic purpura (ITP) risk following live, inactivated, and simultaneous vaccination, with a focus on infants aged < 2 years. We matched case patients with ITP to one or two control patients with other diseases by institution, hospital visit timing, sex, and age. We calculated McNemar’s pairwise odds ratios (ORs [95% confidence interval]) with 114 case–control pairs. The case group had 27 (44%) males and 22 (35%) infants, and the control group included 49 (43%) males and 42 (37%) infants. For all age groups, the McNemar’s OR for ITP occurrence was 1.80 (0.54–6.84, p = 0.64) for all vaccines. Among infants, these were 1.50 (0.17–18.0, p = 0.50) for all vaccines, 2.00 (0.29–22.1, p = 0.67) for live vaccines, and 1.00 (0.01–78.5, p = 0.50) for inactivated vaccines. Sex-adjusted common ORs for simultaneous vaccination were 1.52 (0.45–5.21, p = 0.71) for all vaccines, 1.83 (0.44–7.59, p = 0.40) for inactivated vaccines only, and 1.36 (0.29–6.30, p = 0.69) for mixed live and inactivated vaccines. In infants, these were 1.95 (0.44–8.72, p = 0.38), 1.41 (0.29–6.94, p = 0.67) and 2.85 (0.43–18.9, p = 0.28), respectively. These limited data suggest no significant ITP risk following vaccinations or simultaneous vaccination in any age group, including infants.

Recurrent immune thrombocytopenia following different vaccines

A boy developed immune thrombocytopenia 2 weeks after receiving his measles-mumps-rubella and varicella vaccines at 12 months of age. He then had a recurrent episode 1 week after the booster doses of his quadrivalent diphtheria-tetanus-pertussis-polio, pneumococcal and meningococcal group C vaccines at 5 years of age. On both the occasions he required hospitalisation and treatment with intravenous immunoglobulin. He received other vaccines, before and in between, without any adverse events. Future vaccines are to be determined on an individual risk-benefit basis and he will be reviewed at the age of 11 when his next routine immunisations are due.

Data mining for prospective early detection of safety signals in the Vaccine Adverse Event Reporting System (VAERS): a case study of febrile seizures after a 2010-2011 seasonal influenza virus vaccine

BACKGROUND

Reports of data mining results as an initial indication of a prospectively detected safety signal in the US Vaccine Adverse Event Reporting System (VAERS) have been limited. In April 2010 a vaccine safety signal for febrile seizures after Fluvax(®) and Fluvax(®) Junior was identified in Australia without the aid of data mining. In order to refine Northern Hemisphere influenza vaccine safety surveillance, VAERS data mining analyses based on vaccine brand name were initiated during the 2010-2011 influenza season.

OBJECTIVE

We describe the strategies that led to the finding of a novel safety signal using empirical Bayesian data mining.

METHODS

The primary US VAERS analysis calculated an empirical Bayesian geometric mean (EBGM), which was adjusted for age group, sex and year received. A secondary age-stratified analysis calculated a separate EBGM for 11 pre-defined age subsets. These bi-weekly analyses were generated with database restrictions that separated live and inactivated vaccines as well as with the US VAERS database. A cutoff of 2.0 at the fifth percentile of the confidence interval (CI) for the EBGM, the EB05, was used to identify vaccine adverse event combinations for further evaluation. Examination of potential interactions among concomitantly administered vaccines is based on the Interaction Signal Score (INTSS), which is a relative measure of how much excess disproportionality is present in the three-dimensional combination of two vaccines and one adverse event term. An INTSS >1 indicates that the CI for the three-dimensional analysis is larger than and does not overlap with the CI from the highest two-dimensional analysis. We subsequently examined the possibility of masking by removing all 2,095 Fluzone(®) 2010-2011 reports from the 10 December 2010 version of the VAERS database. In addition, we calculated relative reporting ratios to observe the relative contribution of adjustment and the Multi-Item Gamma Poisson Shrinker (MGPS) algorithm to EBGM values.

RESULTS

On 10 December 2010, US VAERS analyses we found an EB05 >2 for Fluzone(®) 2010-2011 and the Medical Dictionary for Regulatory Activities (MedDRA(®)) term "febrile seizure". MedDRA(®) terminology is the medical terminology developed under the auspices of the International Conference on Harmonization of technical requirements for Registration of Pharmaceuticals for Human Use (ICH). No other vaccine products had independent vaccine-febrile seizure combinations with an EB05 >2. Three-dimensional analyses to examine possible interactions among vaccine products concomitantly administered with Fluzone(®) 2010-2011 yielded Interaction Signal Score values <1. Removal of all Fluzone(®) 2010-2011 reports from the VAERS database failed to demonstrate a previously masked vaccine adverse event pair with an EB05 >2. The inactivated vaccine database restriction resulted in a 41 % reduction in background VAERS reports and a 24 % reduction in foreground VAERS reports.

CONCLUSION

Empirical Bayesian data mining in VAERS prospectively detected the safety signal for febrile seizures after Fluzone(®) 2010-2011 in young children. The EB05 threshold, database restrictions, adjustment and baseline data mining were strategies adopted a priori to enhance the specificity of the 2010-2011 influenza vaccine data mining analyses. A database restriction used to separate live vaccines resulted in a reduced EB05. Adjustment of data mining analyses had a larger effect on estimates of disproportionality than the MGPS algorithm. Masking did not appear to influence our findings. This case study illustrates the value of VAERS data mining for vaccine safety monitoring.

Vaccine administration and the development of immune thrombocytopenic purpura in children

The most important reasons cited by the opponents of vaccines are concerns about vaccine safety. Unlike issues such as autism for which no indisputable documentation of direct relationship with vaccine use is available, immune thrombocytopenic purpura (ITP) is an adverse event that can really follow vaccine administration, and may limit vaccine use because little is known about which vaccines it may follow, its real incidence and severity, the risk of chronic disease, or the possibility of recurrences after new doses of the same vaccine. The main aim of this review is to clarify the real importance of thrombocytopenia as an adverse event and discuss how it may interfere with recommended vaccination schedules. The available data clearly indicate that ITP is very rare and the only vaccine for which there is a demonstrated cause-effect relationship is the measles, mumps and rubella (MMR) vaccine that can occur in 1 to 3 children every 100,000 vaccine doses. However, also in this case, the incidence of ITP is significantly lower than that observed during the natural diseases that the vaccine prevents. Consequently, ITP cannot be considered a problem limiting vaccine use except in the case of children suffering from chronic ITP who have to receive MMR vaccine. In these subjects, the risk-benefit ratio of the vaccine should be weighed against the risk of measles in the community.

U.S. Postlicensure safety surveillance for adolescent and adult tetanus, diphtheria and acellular pertussis vaccines: 2005-2007

BACKGROUND

Pre-licensure clinical trials for two U.S. licensed tetanus toxoid, reduced diphtheria toxoid and acellular pertussis (Tdap) vaccines did not reveal any major safety concerns. However, routine use in large adolescent and adult populations could reveal rare and potentially serious adverse events (AEs).

METHODS

To characterize reported AEs following Tdap vaccination and identify potential safety concerns warranting further evaluation, we analyzed data from the Vaccine Adverse Event Reporting System (VAERS) and assessed the frequency and proportions of AEs and reporting rates (reports per 100,000 vaccine doses distributed).

RESULTS

A total of 2090 reports (7% were serious; 55% listed Tdap alone) involving Tdap vaccines were submitted to VAERS May 2005-June 2007. The crude reporting rate was 10.2 per 100,000 vaccine doses distributed. The median age of vaccinees was 22 years, and the female to male ratio was about 2 to 1. The majority of reports described common local and systemic signs and symptoms, such as injection site reactions, fever, and headache. Rarely reported AEs included myopericarditis, demyelinating diseases of the central nervous system, Guillain-Barré Syndrome, syncope, encephalopathy/encephalitis, seizure, Bell's palsy, anaphylaxis, and thrombocytopenia.

CONCLUSIONS

Because adolescents and adults were not routinely vaccinated against pertussis in the past, this surveillance summary provides important - and reassuring - information about the use of Tdap in these age groups. Although subject to the limitations of passive surveillance, the findings of this VAERS review support the pre-licensure clinical trial data with regard to the safety of the U.S. licensed Tdap vaccines. Continued monitoring of clinically significant AEs that are temporally associated with Tdap vaccination and further assessment of such events using controlled observational studies may provide additional information about the safety of these vaccines.

The risk of immune thrombocytopenic purpura after vaccination in children and adolescents

BACKGROUND

The risk of immune thrombocytopenic purpura (ITP) after childhood vaccines other than measles-mumps-rubella vaccine (MMR) is unknown.

METHODS

Using data from 5 managed care organizations for 2000 to 2009, we identified a cohort of 1.8 million children ages 6 weeks to 17 years. Potential ITP cases were identified by using diagnostic codes and platelet counts. All cases were verified by chart review. Incidence rate ratios were calculated comparing the risk of ITP in risk (1 to 42 days after vaccination) and control periods.

RESULTS

There were 197 chart-confirmed ITP cases out of 1.8 million children in the cohort. There was no elevated risk of ITP after any vaccine in early childhood other than MMR in the 12- to 19-month age group. There was a significantly elevated risk of ITP after hepatitis A vaccine at 7 to 17 years of age, and for varicella vaccine and tetanus-diphtheria-acellular pertussis vaccine at 11 to 17 years of age. For hepatitis A, varicella, and tetanus-diphtheria-acellular pertussis vaccines, elevated risks were based on one to two vaccine-exposed cases. Most cases were acute and mild with no long-term sequelae.

CONCLUSIONS

ITP is unlikely after early childhood vaccines other than MMR. Because of the small number of exposed cases and potential confounding, the possible association of ITP with hepatitis A, varicella, and tetanus-diphtheria-acellular pertussis vaccines in older children requires further investigation.