(128) Safety of Moderna mRNA-1273.214 and mRNA-1273.222 COVID-19 bivalent vaccines: results from post-marketing surveillance in South Korea

Background: Prospective cohort monitoring programs are conducted to monitor adverse events (AE) following administration of newly authorized products in South Korea (SK) in accordance with regulations. Active prospective surveillance to evaluate the safety of Moderna COVID-19 bivalent vaccines (mRNA-1273.222 and mRNA-1273.214) was conducted.

Objectives: To assess the safety of Moderna COVID-19 bivalent vaccines in SK.

Methods: Individuals vaccinated with Spikevax bivalent as per the local label were included in the survey. Consented individuals provided information about medical and vaccination history, concomitant medications at the time of vaccination and were followed up for 28 days. Details of the AE including the severity, and outcome of the AE were collected using patient diary. Solicited local (pain, tenderness, erythema/redness, or induration/swelling) and systemic (fever, headache, fatigue, myalgia, arthralgia, nausea/vomiting, or shivering) reactogenic AE were captured 6 days after vaccination. Unsolicited AE were captured 28 days after vaccination.

The percentage of individuals experiencing AE were presented along with 95% confidence interval (CI). The analysis was further stratified by severity.

Results: The interim results for data period of March 8, 2023, to September 7, 2023, are presented here. For mRNA-1273.222, 443 individuals with complete patient diary were analyzed. Of these, 174 (39.3%) were elderly (≥ 65 years) and 202 (45.6%) were males. Approximately 50% of individuals reported presence of comorbidities and concomitant medications. Solicited AE after vaccination were reported by 98 (22.1%, 95% CI: 18.3, 26.3) individuals, 61 (13.8%, 95% CI: 10.7, 17.3) local and systemic AE. The most common solicited AE was injection site pain reported by 71 (16.0%) individuals. Among individuals with solicited AE, 97 (21.9%) were Grade 1 and 2 (0.5%) were Grade 2 severity, which were resolved. There was only one unsolicited Grade 1 AE reported which resolved.

For mRNA-1273.214, 49 individuals with complete patient diary were analyzed. Of these, 20 (40.8%) were elderly and 21 (42.9%) were males. Comorbidities and concomitant medications were reported by 34 (69.4%) individuals. Solicited AE were reported by 6 (12.2%, 95% CI: 4.6, 24.8) individuals, 4 (8.2%) local and 2 (4.1%) systemic AE. All 6 cases were of Grade 1 severity and were resolved. There was no unsolicited AE reported following mRNA-1273.214.

Conclusions: The results of this post-marketing surveillance in SK were consistent with the known safety profile of Moderna’s Spikevax bivalent vaccines. The most common AE after Moderna’s Spikevax bivalent vaccines was the local reactogenicity symptom of injection site pain with Grade 1 severity.