Acute Lung Injury Accompanying Alveolar Hemorrhage Associated with Flu Vaccination in the Elderly

A Case of Diffuse Alveolar Hemorrhage With COVID-19 Vaccination

With the growing rates of vaccination against coronavirus disease 2019 (COVID-19) across the globe, rare side effects have been increasingly noticed on a post-marketing basis. Cases of myocarditis and pericarditis have been reported in the literature following COVID messenger RNA (mRNA) vaccination. However, diffuse alveolar hemorrhage (DAH) following vaccination has not been reported. DAH is a life-threatening clinicopathological entity characterized by bleeding into the alveolar space from pulmonary microvasculature. It presents a diagnostic challenge in the setting of acute respiratory failure, requiring prompt suspicion and workup. We report a case of a 59-year-old male with a recent COVID-19 infection who presented with DAH within eight hours of the first dose of mRNA vaccination (Moderna, Cambridge, MA). Bronchial alveolar lavage was performed, along with imaging of the chest, to confirm the diagnosis. Immunological workup with rheumatoid factor, anti-citrullinated peptide, anti-neutrophil cytoplasmic antibodies (P-ANCA and C-ANCA), anti-glomerular basement antibodies, Anti-double-stranded DNA, C3 and C4 complement levels, and cryoglobulin were all negative. Infectious workup with cultures and PCR from bronchial lavage was also negative. In the absence of any other causes, the etiology was likely deemed to be vaccine-induced DAH. Herein, we also discuss the possible mechanism of vaccine-related DAH and emphasize the need for further studies on vaccine-related adverse events.

Influenza Vaccination-associated Acute Thrombocytopenia and Diffuse Alveolar Hemorrhage

Influenza vaccination can trigger various adverse reactions, and thrombocytopenia is also rarely reported. Although patients with mild thrombocytopenia are sometimes asymptomatic, severe thrombocytopenia can cause severe bleeding. We herein report a rare case of severe thrombocytopenia that occurred within one day of influenza vaccination and diffuse alveolar hemorrhage (DAH) leading to acute respiratory failure. The patient was treated with glucocorticoid pulse therapy, intravenous immunoglobulin, and temporary mechanical ventilation, and eventually he made a full recovery. Vaccine-related thrombocytopenia and DAH should be considered adverse reactions, even if they develop very soon after vaccination.

Heterosubtypic T-Cell Immunity to Influenza in Humans: Challenges for Universal T-Cell Influenza Vaccines

Influenza A virus (IAV) remains a significant global health issue causing annual epidemics, pandemics, and sporadic human infections with highly pathogenic avian or swine influenza viruses. Current inactivated and live vaccines are the mainstay of the public health response to influenza, although vaccine efficacy is lower against antigenically distinct viral strains. The first pandemic of the twenty-first century underlined the urgent need to develop new vaccines capable of protecting against a broad range of influenza strains. Such “universal” influenza vaccines are based on the idea of heterosubtypic immunity, wherein immune responses to epitopes conserved across IAV strains can confer protection against subsequent infection and disease. T-cells recognizing conserved antigens are a key contributor in reducing viral load and limiting disease severity during heterosubtypic infection in animal models. Recent studies undertaken during the 2009 H1N1 pandemic provided key insights into the role of cross-reactive T-cells in mediating heterosubtypic protection in humans. This review focuses on human influenza to discuss the epidemiological observations that underpin cross-protective immunity, the role of T-cells as key players in mediating heterosubtypic immunity including recent data from natural history cohort studies and the ongoing clinical development of T-cell-inducing universal influenza vaccines. The challenges and knowledge gaps for developing vaccines to generate long-lived protective T-cell responses is discussed.