COVID-19 breakthrough infections and pre-infection neutralizing antibody

Abstract

Background: While increasing coverage of effective vaccines against coronavirus disease 2019 (COVID–19), emergent variants raise concerns about breakthrough infections. Data are limited, however, whether breakthrough infection during the epidemic of the variant is ascribed to insufficient vaccine–induced immunogenicity. Methods: We described incident COVID–19 in relation to the vaccination program among workers of a referral hospital in Tokyo. During the predominantly Delta epidemic, we followed 2,473 fully vaccinated staff (BNT162b2) for breakthrough infection and selected three matched controls. We measured pre–infection 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 two 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 had returned to work early. There was no measurable difference between cases and controls in pre–infection neutralizing antibody titers against the wild–type, Alpha, and Delta, and anti–spike antibody titers, while neutralizing titers against the variants were considerably lower than those against the wild–type. Conclusions: Pre–infection neutralizing antibody titers were not decreased among patients with breakthrough infection under the Delta variant rampage. The result points to the importance of infection control measures in the post–vaccination era, irrespective of immunogenicity profile.

Genomic Surveillance of SARS CoV2 in COVID-19 vaccinated healthcare workers in Lebanon

“…Despite the rollout of effective COVID-19 vaccines, breakthrough infections have been increasingly reported worldwide specifically among HCWs [4,8,21,38]. The incidence of breakthrough infections among vaccinated HCWs is low and it was recently estimated at 0.011 to 0.001 per 100 individuals [39].…”

“…The use of personal protective equipment (PPE) including mask mandates for patients and visitors significantly reduced the occupational risk of acquiring COVID-19 by HCWs [20]. However, waning immunity and the emergence of antigenically drifted VOCs meant that HCWs are at risk of breakthrough infections [4,5,8,21]. Among 22,729 HCWs in the US who received at least one dose of an mRNA-based vaccine (BNT162b2 or mRNA-1273), 189 tested positive for SARS-CoV-2 [6].…”

“…More than 11.4 billion vaccine doses have been administered worldwide since the start of COVID-19 vaccine rollout in December 2020 [1]. Despite the availability of effective vaccines against SARS-CoV-2, reports of breakthrough infections among vaccinated individuals are increasingly reported globally [4][5][6][7][8].…”