Neutralizing Antibodies as Predictors of Vaccine Breakthrough Infection in Healthcare Workers Vaccinated with or without a Heterologous Booster Dose: A Cohort Study during the Third COVID-19 Wave in Peru

We evaluated neutralizing antibody (NAbs) levels as a protective factor against vaccine breakthrough infection (VBI) in healthcare workers (HCWs) during the third COVID-19 wave in Peru. This retrospective cohort study employed the information from a private laboratory in Lima (Peru) of HCW who received only two BBIBP-CorV vaccines or (additionally) a heterologous booster with BNT162b2. We evaluated the association between the VBI and the levels of NAbs at 21, 90, 180, and 210 days after the BBIBP-CorV second dose. NAbs were calculated with the cPass (TM) SARS-CoV-2 Neutralization Antibody Detection kit (surrogate virus neutralization test (sVNT)) and the Elecsys((R)) anti-SARS-CoV-2 S Test. Of the 435 HCW evaluated, 31.72% had an infection previous to vaccination, 68.28% received a booster dose, and 23.21% had a VBI during the third wave. The variables associated with a lower risk of VBI were male sex (aRR: 0.43) and those who had (180 days after BBIBP-CorV inoculation) NAbs levels >= 60% (aRR: 0.58) and >= 90% (aRR: 0.59) on cPass (TM), and >= 500 with Elecsys((R)) (aRR: 0.58). HCW whose NAbs persisted at higher levels six months after the BBIBP-CorV showed a lower risk of suffering from a VBI during the third COVID-19 wave.

Automated summary

We evaluated the levels of neutralizing antibodies (NAbs) as a protective factor against vaccine breakthrough infection (VBI) in healthcare workers (HCWs) during Peru's third COVID-19 wave. This retrospective cohort study used data from a private laboratory in Lima, Peru, and included HCWs who received either two doses of BBIBP-CorV vaccine or a heterologous booster with BNT162b2. We found that HCWs with higher levels of NAbs, measured at various time points after BBIBP-CorV vaccination, had a lower risk of VBI during the third wave of COVID-19.