This case report presents a patient who developed eosinophilia and lymphadenopathy after receiving the third dose of the Sinopharm COVID-19 vaccine. While post-vaccination lymphadenopathy is a well-documented phenomenon 8, the occurrence of eosinophilia is less common.
There are several reports of the occurrence of lymphadenopathy after receiving COVID-19 vaccines. As an example, Cocco et al. reported some patients who developed lymphadenopathy after receiving Pfizer, Moderna and AstraZeneca Covid-19 vaccines 8. This happened within a few days to a few weeks after receiving the vaccine, and it mostly resolved itself in the follow-up of the patients8.
A recent study by Westreich et al. identified 16 cases of peripheral eosinophilia in approximately 41,000 individuals vaccinated with the Pfizer or Moderna COVID-19 vaccines. The study found that eosinophilia was associated with various clinical manifestations, including respiratory symptoms, skin conditions, and systemic involvement. Some patients required treatment with oral corticosteroids or anti-IL-5 biologics. Additionally, several patients had underlying conditions like asthma or atopy7.
Table 3 presents a collection of reported cases where individuals experienced eosinophilic events following COVID-19 vaccination 9–15. The data highlights the diversity of eosinophilic conditions observed, including unexplained hypereosinophilia, hypereosinophilic syndrome, eosinophilic pneumonia, and eosinophilic granulomatosis with polyangiitis (EGPA). The reported cases involve individuals of varying ages, ranging from teenagers to adults. Both males and females are represented in the data. This suggests that eosinophilic complications can occur in a wide range of individuals, regardless of age or sex.
The table also details the types of vaccines involved and the timing of onset of symptoms after vaccination. While the majority of cases involve mRNA-based vaccines (e.g., Pfizer-BioNTech, Moderna), one case involved the inactivated Sinopharm vaccine. The onset of symptoms varied, with some cases occurring within days or weeks of vaccination, while others developed months later.
The primary treatments administered to patients in these cases include corticosteroids (e.g., methylprednisolone), immunosuppressants (e.g., cyclophosphamide, rituximab), and supportive care. In most cases, patients experienced clinical improvement following treatment. However, it is essential to note that the long-term outcomes of these cases may vary, and further follow-up is necessary to assess the durability of the responses.
Table 3
Summary of Reported Eosinophilic Events Following COVID-19 Vaccination
| Study, Year | Age, Sex | Vaccine | Onset | Diagnosis | Main Treatments | Outcome |
| Our case | 66-year-old man | Sinopharm | Two months after receiving 3rd dose | Unexplained eosinophilia and lymphadenopathy | Antibiotics Supportive care | Clinical improvement |
| Hoxha et al.9 | 48-year-old man | BioNTech/Pfizer | Five days after first dose | Multi-organ involvement, clinical and laboratory findings suggestive of hypereosinophilic syndrome | Methylprednisolone Anticoagulation Acetylsalicylic acid Mepolizumab | Clinical improvement |
| Piqueras et al. 10 | 37-year-old man | Pfizer-BioNTech | Two days after receiving | Acute eosinophilic pneumonia with 60% eosinophils in alveolar lavage | - | Clinical improvement |
| Miqdadi et al. 11 | 66-year-old man | AstraZeneca | Five hours after receiving | Acute respiratory distress, leukocytosis and eosinophilia (25%) on CBC | Methylprednisolone | Clinical improvement |
| Mahdi et al. 12 | Middle-aged man | Pfizer-BioNTech | Ten days after receiving | EGPA | Methylprednisolone Rituximab Cyclophosphamide Intravenous immunoglobulin | Clinical improvement |
| Hwang et al. 13 | 71-year-old woman | Pfizer-BioNTech | After receiving | EGPA | Methylprednisolone Cyclophosphamide | Clinical improvement |
| Nappi et al. 14 | 63-year-old man | Moderna | One day after receiving a booster dose | Multiorgan involvement suggesting EGPA | Methylprednisolone Cyclophosphamide | Clinical improvement |
| Ramezanzade et al. 15 | 15-year-old boy | Sinopharm | 1 month after 2nd dose | ANCA-associated vasculitis | Prednisolone Cellcept | Clinical improvement |
Our case is unique in reporting hypereosinophilia following the Sinopharm COVID-19 vaccine, particularly given the limited number of reported cases involving inactivated vaccines. While a causal relationship cannot be definitively established based on this single case, the temporal association between vaccination and symptom onset warrants further investigation.
A possible explanation for the eosinophilia observed in these patients is a TH2 skewing effect caused by the vaccine, akin to the proposed mechanism of the previously observed vaccine-associated enhanced disease 16,17. This phenomenon has been noted in humans in vaccine trials for dengue virus, respiratory syncytial virus, and measles, as well as in animal models for other coronaviruses including SARS-CoV-1 7. These vaccines were found to promote immune responses that exacerbated disease after subsequent infection. Vaccine-associated enhanced disease has predominantly been reported to exacerbate respiratory disease; pulmonary eosinophilia is a characteristic feature 7.
Larger studies and comprehensive follow-up are necessary to elucidate the exact relationship between COVID-19 vaccines and eosinophilic disorders. This case highlights the importance of continued vigilance for unexpected adverse events following vaccination. Further research is needed to confirm the association between the Sinopharm vaccine and eosinophilic disorders and to elucidate the underlying mechanisms. Additionally, larger studies are required to assess the prevalence and clinical significance of eosinophilic events following COVID-19 vaccination.