Evaluation of the safety and immunogenicity of new vaccine platforms is needed to increase public acceptance of coronavirus disease 2019 (COVID-19) vaccines. Here, we evaluated the association between reactogenicity and immunogenicity in healthy adults following vaccination by analyzing blood samples before and after sequential two-dose vaccinations of BNT162b2 and ChAdOx1 nCoV-19. Outcomes included anti-S IgG antibody and neutralizing antibody responses, adverse events, and proinflammatory cytokine responses. A total of 59 and 57 participants vaccinated with BNT162b2 and ChAdOx1 nCoV-19, respectively, were enrolled. Systemic adverse events were more common after the first ChAdOx1 nCoV-19 dose than after the second. An opposite trend was observed in BNT162b2 recipients. Although the first ChAdOx1 nCoV-19 dose significantly elevated the median proinflammatory cytokine levels, the second dose did not, and neither did either dose of BNT162b2. Grades of systemic adverse events in ChAdOx1 nCoV-19 recipients were significantly associated with IL-6 and IL-1β levels. Anti-S IgG and neutralizing antibody titers resulting from the second BNT162b2 dose were significantly associated with fever. In conclusion, systemic adverse events resulting from the first ChAdOx1 nCoV-19 dose may be associated with proinflammatory cytokine responses rather than humoral immune responses. Febrile reactions after second BNT162b2 dose were positively correlated with vaccine-induced immune responses rather than with inflammatory responses.

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Background Monovalent meningococcal conjugate vaccines against serogroups A or C have resulted in significant reduction of pharyngeal carriage rates against the vaccine serogroups. However, the effect of the quadrivalent meningococcal conjugate vaccine on meningococcal carriage has not yet been evaluated. Methods We assessed changes in pharyngeal carriage rates of Neisseria meningitidis after introduction of the quadrivalent meningococcal conjugate vaccine in Korean military trainees. Two rounds of oropharyngeal swabs of Korean military trainees were obtained, at the beginning and the end of the army training period. The first oropharyngeal swabs were collected prior to vaccination; the second round was performed 5 weeks later. Results In 2013, the overall N. meningitidis carriage rate was higher at the end of the training period (13.8%, 60 of 434 participants) than upon entry into military service (8.9%, 39 of 434 participants). Although the carriage rates of nongroupable and serogroup X isolates increased over the 5-week interval, carriage of the serogroup strains included in the quadrivalent meningococcal vaccine was reduced, from 7 to 2 isolates, after vaccination. However, in 2014, the overall carriage rate of N. meningitidis was significantly lower at the end of the training period (5.2%, 23 of 443 participants) than on entry into military service (12.6%, 56 of 443 participants) (p = 0.028). Carriage of vaccine serogroups isolates was significantly decreased, compared to that of non-vaccine serogroup B over the 5-week interval. Carriage isolates belonging to the ST-178, ST-31 and ST-41/44 were frequently identified clonal complex. Meningococcal carriage rate before and after Meningococcal vaccination in Korean military trainees Conclusion Meningococcal vaccination in Korean military trainees could lead to reduce pharyngeal carriage rates of vaccine serogroup meningococci. Therefore, the quadrivalent meningococcal conjugate vaccine is likely to prevent carriage acquisition of meningococci in closed populations such as military trainees. Disclosures All Authors: No reported disclosures.

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