Chlorhexidine is a synthetic bisbiguanide antiseptic and was introduced in healthcare use in 1954. Allergy to chlorhexidine has been increasingly reported particularly in the perioperative and medical procedural settings. The hypersensitivity reactions range from mild cutaneous reactions to anaphylaxis or death. There are many products and medical devices containing chlorhexidine that sometimes lack standardized labeling. With the various routes of chlorhexidine exposure, accidental or recurrent reactions in chlorhexidine-allergic patients have been reported. Therefore, we aim to review the most recent evidence in clinical manifestations, diagnostic methods, management, and preventive measures with a focus on the unique features of chlorhexidine allergy.

Anaphylaxis to CoronaVac, an inactivated vaccine against COVID-19, is extremely rare. We report 12 cases of anaphylaxis after CoronaVac administration, focusing on clinical characteristics and management outcomes. Skin test and graded vaccine challenge were successfully performed in our cases and might be considered if an inactivated vaccine is the only remaining option.

The different strains of SARS-CoV-2 were detected and labeled in 2021. Each strain differs in both clinical symptoms and severity. Previous studies found different clinical symptoms and treatment outcomes between outbreak waves; however, data in Southeast Asia were limited. This study collected data of hospitalized COVID-19 patients from a Tertiary hospital in Thailand between January 2020 and December 2023 and analyzed patients’ data in each outbreak wave using Pearson’s chi-square. A total of 1084 inpatients were included for analysis. The median age was 64 (IQR, 0.4–100) years. The patients were hospitalized in predominantly Alpha (22.78%), Delta (21.68%), and Omicron (5.07%) periods of the virus outbreak. The largest age group was elderly (over 65 years old) in all three variant of concern (VOC) periods; 82.65% of the patients had comorbidities, including 58.5% hypertension, 46.5% dyslipidemia, and 42.0% diabetes mellitus (DM). The study found pneumonia at 67.53%, septic shock at 4.61%, acute respiratory distress syndrome (ARDS) at 2.86%, and congestive heart failure at 0.83% in all age groups with no significant difference between outbreak periods. The overall mortality rate was 16.14%. A total of 75% of deaths occurred in patients over 65 years old. The mortality rates in each VOC period were 20.0% Delta, 19.83% Alpha, and 13.23% Omicron. In the elderly group, the mortality rates were Delta 15.32%, Alpha 11.75%, and Omicron 10.88%. The Omicron VOC was less severe than other variants, particularly in the elderly (≥65 years). There were no significant differences in the younger (<65 years) age group. The elderly still had more severe symptoms and the highest mortality rates in every wave of outbreak.

Chiewchalermsri C, et al. Allergy Asthma Immunol Res. 2023 May;15(3):336-347. https://doi.org/10.4168/aair.2023.15.3.336

Purpose: Atopic patients have more risk of adverse drug reactions. COVID-19 vaccination is very important in the current situation. We still do not have data about risks of adverse effects from vaccine in atopic patients. The goal of our study was to evaluate atopic risks and adverse effects of live-attenuated Oxford/AstraZeneca COVID-19 vaccination. Patients and methods: Data was collected using a prospective descriptive cohort study from participants 18 years old and above who came to the Outpatient Department, Panyananthaphikkhu Chonprathan Medical Center for live-attenuated COVID-19 vaccination between March and December 2021. The sample size was 3016 individuals. The information about adverse reactions at 6, 2, 72 hours and 7.30 and 60 days after each live-attenuated Oxford/AstraZeneca COVID-19 vaccination was collected by telephone. Participants with history of severe allergic reaction to vaccine components were excluded. Results: There were 732 atopic patients and 2284 non-atopic patients. Atopic patients included 556 with allergic rhinitis, 83 with asthma, 23 with urticaria and 73 with food allergies. The underlying diseases of hypertension, hyperlipidemia and hyperthyroidism were more common in non-allergic patients, with p-value < 0.001, < 0.001 and 0.042, respectively. Atopic patients developed significantly more fever, nausea and vomiting, skin rash (urticaria), and local reaction than non-atopic patients, with p-values of < 0.001, 0.018, < 0.001 and < 0.001, respectively. Conclusion: Atopic patients had more risk of adverse reactions to live-attenuated Oxford/AstraZeneca COVID-19 vaccination. No life-threatening adverse reaction was seen. Physicians should screen atopic risks in people who are getting vaccinated. Atopic patients should be knowledgeable about their risk and how to monitor clinical reactions by themselves.