Physicians have seen an increase of hives in patients following the Covid vaccine, but to date there have been no formal studies documenting patients who already have existing chronic urticaria.
The rapid development and rollout of the vaccine for COVID-19 has led to unexpected adverse reactions during mass vaccination. Delayed onset hives is a common reaction seen after vaccination. Some reports have listed the incidence of it at approximately 1%. Most patients of hives resolve within a week of medical treatment, some patients have progressed to chronic urticaria that required continued use of antihistamines or even Xolair.
The incidence of chronic hives after the COVID-19 booster vaccination was approximately 20/100,000 in Switzerland. The incidence of the COVID-19 mRNA vaccine on preexisting chronic hives is not well known. One study has showed that 13.8% experienced an exacerbation after vaccination. This can lead to a substantial burden of disease for patients.
Chronic hives is a complex disease with a lot of internal and external factors. The goal of management is to achieve complete control of symptoms. After using high dose oral antihistamines, Xolair is available for refractory cases.
In a study published in The Journal of Allergy and Clinical Immunology: In Practice, titled “Exacerbation of Chronic Spontaneous Urticaria Following Coronavirus Disease 2019 (COVID-19) Vaccination in Omalizumab-Treated Patients, the authors investigated the impact of the vaccine on patients with stable hives already on Xolair and to identify the risk factors for exacerbations.
The results showed that 14.3% of patients experienced aggravation of hives at least once after COVID-19 vaccination. In the study it showed the Pfizer vaccine caused a higher percentage than Moderna.
Other studies have showed in patients without preexisting hives can also develop urticarial rashes, most cases however do resolve with antihistamines within days to weeks.
The authors suggest that mast cells are not fully suppressed with Xolair and are readily degranulated by immune reactions induced by vaccination.
Most patients are safely able to get the vaccine, but patients and physicians should be aware of hives or a hive recurrence in patients with chronic urticaria. As more vaccines are developed we may see this with other treatments.
Update November 15, 2023
A recent study was published that aimed to investigate the rates of and risk factors for chronic urticaria exacerbation as well as the frequency of adverse reactions including allergic reactions in patients vaccinated against COVID-19. 2769 patients participated in the study, key findings in the article titled “Urticaria exacerbations and adverse reactions in patients with chronic urticaria receiving COVID-19 vaccination: Results of the UCARE COVAC-CU study were:
- The rate of COVID-19 vaccination induced chronic hives exacerbation was 9%. Hives exacerbation most often started less than 48 hours after the vaccine, lasted for a few weeks or less and was mainly treated with antihistamines. Vaccine related side effects were mostly local reactions, fever, fatigue and muscle pain.
- Factors that increased the risk for COVID-19 vaccination induced chronic urticaria exacerbation included female gender, disease duration less than 24 months, having chronic spontaneous urticaria (vs inducible urticaria), use of adenovirus viral vector vaccine, NSAID/aspirin intolerance, having concerns about the vaccine.
- Being on Xolair and Latino/Hispanic ethnicity lowered the risk
The authors concluded “COVID-19 vaccination leads to disease exacerbation in only a small number of Chronic Urticaria patients and is generally well tolerated.”