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.

Hypersensitivity pneumonitis.

Hypersensitivity pneumonitis (HP), also referred to as extrinsic allergic alveolitis, is characterized by non-immunoglobulin E mediated inflammation of the parenchyma, alveoli, and terminal airways of the lung initiated by inhaled antigens in a susceptible host. Etiologic agents of HP are either organic high-molecular-weight compounds (e.g., bacteria, fungi, amoebae, plant and animal proteins) or inorganic low-molecular-weight haptens (e.g., isocyanates) and drugs (including amiodarone, nitrofurantoin, and minocycline). Six significant predictors have been identified that provide approximately 95% diagnostic accuracy. These six predictors are (1) exposure to a known offending allergen, (2) positive precipitating antibodies to the offending antigen, (3) recurrent episodes of symptoms, (4) inspiratory crackles on lung auscultation, (5) symptoms that occur 4-8 hours after exposure, and (6) weight loss. HP is staged into acute, subacute, and chronic. In the acute stage, after direct exposure to the antigen, there are fever, chills, nonproductive cough, dyspnea, malaise, and myalgias, all of which resemble influenza. However, if obtained, a chest radiograph demonstrates nodular infiltrates, and pulmonary function testing is restrictive (unless the cause is avian, in which case, obstruction or obstruction with restriction is present). In the chronic stage, fever and chills are absent, but weight loss can occur. The immunologic response includes activated macrophages and CD8+ cytotoxic lymphocytes, and bronchoalveolar lavage fluid reveals marked lymphocytosis with a ratio of CD4+ to CD8+ cells of <1. Activated macrophages have increased expression of CD80/CD86, and T cells have increased expression of its counter-ligand, CD28, evidence for heightened antigen presentation.

Anaphylaxis.

Anaphylaxis is a sudden onset, immediate reaction that implies a risk of death. Think of a "rule of 2s" for anaphylaxis, which implies that reactions usually begin within 2 minutes to 2 hours after injection, infusion, ingestion, contact, or inhalation. Fatalities can be from asphyxiation from laryngeal or oropharyngeal swelling, collapse from hypotensive shock, cardiac arrest, or acute severe bronchoconstriction that causes respiratory failure and arrest. When there is activation of mast cells and basophils in anaphylaxis, chemical mediators are detectable. The preformed mediators from mast cells include histamine, tryptase, carboxypeptidase A, and proteoglycans (heparin, chondroitin sulfates). Newly synthesized mediators include prostaglandin D2, leukotriene D4, and platelet activating factor. Crucial actions of the mediators include an abrupt increase in vascular permeability, vascular smooth muscle relaxation, and bronchial smooth muscle contraction. Anaphylaxis can be classified into immunologic, nonimmunologic, or idiopathic based on the associated mechanism. For example, immunologic causes of anaphylaxis are those mediated by immunoglobulin E (IgE) antibodies acting through the FcεR I (foods, insect venom, 32 ß-lactam antibiotics), whereas non-IgE immunologic anaphylaxis is mediated without the presence of anti-allergen IgE antibodies or via FcεRI activation (radiographic contrast material). Nonimmunologic anaphylaxis involves mast cell mediator release such as occurs with exercise or with cold temperature exposure, or from medications such as opioids or vancomycin. Idiopathic anaphylaxis involves mast cell activation (acutely elevated urine histamine or serum tryptase) and activated lymphocytes. Because anaphylaxis is a medical emergency, the drug of choice is epinephrine, not H1 antihistamines or H2 receptor antagonists.

Eosinophilic esophagitis.

Eosinophilic esophagitis (EoE) is defined by symptoms related to esophageal dysfunction, persistent esophageal eosinophilia, and exclusion of other etiologies that may be contributing to the condition. EoE is different from erosive esophagitis. In children, symptoms vary by age groups, such as feeding disorders in 2 year olds; vomiting in 8 year olds; and abdominal pain, dysphagia, and/or food impaction in adolescents. Most adults present with dysphagia, food impaction, heartburn, or chest pain. Common endoscopic features in adults with EoE include linear furrows (creases that orient longitudinally), mucosal rings (esophageal "trachealization"), small-caliber esophagus, white plaques or exudates (which are microabscesses of eosinophils), and strictures. Children often present with similar endoscopic features, yet one-third of pediatric patients with EoE have a normal result in an endoscopic examination. Histologic features of EoE include increased intramucosal eosinophils in the esophagus (≥15 eosinophils per high power field), without similar findings in the stomach or duodenum. There also may be eosinophilic microabscesses. In addition to evidence of mast cell activation, mucosa from patients with EoE have increased levels of interleukin 5; supporting eosinophilia; and upregulation of gene expression of eotaxin-3, a chemokine important in eosinophil migration. The majority of patients have evidence of either aeroallergen and/or food sensitization. Dietary therapy is considered first-line therapy for patients with EoE because it is inexpensive and effective, without requiring pharmacologic therapy. Removal of food antigens has been shown to improve symptoms in patients with EoE. Topical corticosteroids improve esophageal eosinophilia and symptoms, and have become the criterion standard of pharmacotherapy.

Insertion trauma and recovery of function after cochlear implantation: Evidence from objective functional measures.

Partial loss and subsequent recovery of cochlear implant function in the first few weeks following cochlear implant surgery has been observed in previous studies using psychophysical detection thresholds. In the current study, we explored this putative manifestation of insertion trauma using objective functional measures: electrically-evoked compound action potential (ECAP) amplitude-growth functions (ECAP amplitude as a function of stimulus level). In guinea pigs implanted in a hearing ear with good post-implant hearing and good spiral ganglion neuron (SGN) survival, consistent patterns of ECAP functions were observed. The slopes of ECAP growth functions were moderately steep on the day of implant insertion, decreased to low levels over the first few days after implantation and then increased slowly over several weeks to reach a relatively stable level. In parallel, ECAP thresholds increased over time after implantation and then recovered, although more quickly, to a relatively stable low level as did thresholds for eliciting a facial twitch. Similar results were obtained in animals deafened but treated with an adenovirus with a neurotrophin gene insert that resulted in good SGN preservation. In contrast, in animals implanted in deaf ears that had relatively poor SGN survival, ECAP slopes reached low levels within a few days after implantation and remained low. These results are consistent with the idea that steep ECAP growth functions require a healthy population of auditory nerve fibers and that cochlear implant insertion trauma can temporarily impair the function of a healthy SGN population.

Importance of cochlear health for implant function.

Amazing progress has been made in providing useful hearing to hearing-impaired individuals using cochlear implants, but challenges remain. One such challenge is understanding the effects of partial degeneration of the auditory nerve, the target of cochlear implant stimulation. Here we review studies from our human and animal laboratories aimed at characterizing the health of the implanted cochlea and the auditory nerve. We use the data on cochlear and neural health to guide rehabilitation strategies. The data also motivate the development of tissue-engineering procedures to preserve or build a healthy cochlea and improve performance obtained by cochlear implant recipients or eventually replace the need for a cochlear implant. This article is part of a Special Issue entitled .