Abstract
Background: While increasing coverage of effective vaccines against coronavirus disease 2019 (COVID-19), emergent variants raise concerns about breakthrough infection. Data are limited, however, whether breakthrough infection during the epidemic of the variant is ascribed to insufficient vaccine-induced immunogenicity.
Methods: We describe incident COVID-19 in relation to the vaccination program among workers of a referral hospital in Tokyo. During the predominantly Delta epidemic, we followed 2415 fully vaccinated staff (BNT162b2) for breakthrough infection and selected 3 matched controls. We measured post-vaccination neutralizing antibodies against the wild-type, Alpha (B.1.1.7), and Delta (B.1.617.2) strains using live viruses and anti-spike antibodies using quantitative assays, and compared them using the generalized estimating equation model between the 2 groups.
Results: No COVID-19 cases occurred 1-2 months after the vaccination program during the fourth epidemic wave in Japan, dominated by the Alpha variant, while 22 cases emerged 2-4 months after the vaccination program during the fifth wave, dominated by the Delta variant. In the vaccinated cohort, all 17 cases of breakthrough infection were mild or asymptomatic and participants had returned to work early. There was no measurable difference between cases and controls in post-vaccination neutralizing antibody titers against the wild-type, Alpha, Delta, and anti-spike antibody titers, while neutralizing titers against the variants were considerably lower than those against the wild-type.
Conclusions: Post-vaccination neutralizing antibody titers were not decreased among patients with breakthrough infection relative to their controls under the Delta variant outbreak. The result points to the importance of infection-control measures in the post-vaccination era, irrespective of immunogenicity profile.
Keywords: COVID-19; breakthrough infection; neutralizing antibody; vaccination.
【저자키워드】 COVID-19, neutralizing antibody, vaccination., Breakthrough infection, 【초록키워드】 coronavirus disease, viruses, neutralizing antibody, Coronavirus disease 2019, vaccination, Neutralizing antibodies, hospital, variant, Delta, B.1.617.2, delta variant, variants, BNT162b2, Cohort, Epidemic, Coverage, Asymptomatic, B.1.1.7, outbreak, Patient, Control, Japan, Mild, Alpha, Neutralizing, Breakthrough infection, Alpha variant, Strains, anti-spike antibodies, Antibody titers, Neutralizing antibody titer, anti-spike antibody, Neutralizing titer, Quantitative assays, strain, COVID-19 cases, Tokyo, matched controls, epidemic wave, not decreased, COVID-19 case, Effective vaccines, measure, participant, wild-type, neutralizing titers, while, live viruses, controls, the epidemic, raise, selected, occurred, effective vaccine, groups, returned, live virus, 【제목키워드】 Referral, worker, matching,