Identification of severe acute respiratory syndrome coronavirus 2 breakthrough infections by anti-nucleocapsid antibody among fully vaccinated non-healthcare workers during the transition from the delta to omicron wave

Abstract

Uncontrolled transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has led to the emergence of several variants of concern (VOC). As vaccine-induced neutralizing antibodies against VOC waned over time, breakthrough infections (BTIs) have been reported primarily among healthcare workers or in long-term care facilities. Most BTIs were identified by reverse transcription-polymerase chain reaction (RT-PCR) or antigen test for individuals experiencing symptoms, known as symptomatic BTIs. In this study, we detected seroconversion of anti-nucleocapsid (N) antibody to identify both symptomatic and asymptomatic BTIs in a cohort of COVID-19-naive university employees and students following two or three doses of mRNA vaccines. We reported 4 BTIs among 85 (4.7%) participants caused by the Omicron and Delta VOC during the transition from the Delta to Omicron wave of the pandemic; three were symptomatic and confirmed by RT-PCR test and one asymptomatic. A symptomatic reinfection two and half months after a BTI was found in one participant. Two of three symptomatic BTIs and the reinfection were confirmed by whole genome sequencing. All were supported by a >4-fold increase in neutralizing antibodies against the Delta or Omicron variant. Moreover, we found both symptomatic and asymptomatic BTIs can boost neutralizing antibodies against VOC with variable degrees ranging from 2.5- to 77.4-fold increase in neutralizing antibody titers. As BTIs continue, our findings highlight the application of anti-N antibody test to ongoing studies of immunity induced by spike-based vaccine, and provide new insights into the establishment of herd immunity in the community during the post-vaccination era.

Serological assessment of the durability of vaccine-mediated protection against SARS-CoV-2 infection

“…By analyzing the immune responses to vaccination (RBD-specific IgG) and to an antigen encountered only during natural infection (NP-specific IgG) in vaccinated individuals with and without documented histories of infection, we have been able to detect evidence of minor and subclinical infections in a defined study population. Other studies have also monitored vaccinated cohorts for seroconversion to NP, 11 , 12 but to our knowledge, no one has analyzed NP-seroconversion in conjunction with RBD-specific antibody titers to estimate a serum IgG-based correlate of protective immunity.…”

Seroprevalence of SARS-CoV-2 IgG and IgM in Diabetic and Oncology patients at Pietersburg Hospital, Limpopo, South Africa

“…The severe acute respiratory syndrome coronavirus 2 (SARS-COV-2), the causative agent for the coronavirus disease 2019 (COVID- 19), has ravaged the world for over two years since reported in 2019 [1]. As of December 2022, the virus has caused over 650 million infections and over 6.5 million deaths worldwide [2].…”