Objective: The protection from SARS-CoV-2 infection induced by SARS-CoV-2 anti-S1 and anti-S2 IgG antibody positivity resulting from natural infection was evaluated. Methods: The frequency of SARS-CoV-2 infection (as determined by virus RNA detection) was evaluated in a group of 1,460 seropositive and a control group of 8,150 seronegative healthcare workers in three Centres of Northern Italy in the period June-November 2020. Neutralizing serum titers were analyzed in seropositive subjects with or without secondary SARS-CoV-2 infection. Results: During the 6-month survey, 1.78% seropositive subjects developed secondary SARS-CoV-2 infection while 6.63% seronegative controls developed primary infection (odds ratio: 0.26; 95% confidence interval: 0.17-0.38). Secondary infection was associated with low or absent serum neutralizing titer (p<0.01) and was mildly symptomatic in 45.8% cases vs 71.4% symptomatic primary infections (odds ratio: 0.34; 95% confidence interval: 0.16-0.78). Conclusions: Immunity from natural infection appears protective from secondary infection; therefore, vaccination of seronegative subjects might be prioritized.

Incidence of SARS-CoV-2 infection in health care workers from Northern Italy based on antibody status: immune protection from secondary infection- A retrospective observational case-control study

De Vito, Giovanni;
2021-01-01

Abstract

Objective: The protection from SARS-CoV-2 infection induced by SARS-CoV-2 anti-S1 and anti-S2 IgG antibody positivity resulting from natural infection was evaluated. Methods: The frequency of SARS-CoV-2 infection (as determined by virus RNA detection) was evaluated in a group of 1,460 seropositive and a control group of 8,150 seronegative healthcare workers in three Centres of Northern Italy in the period June-November 2020. Neutralizing serum titers were analyzed in seropositive subjects with or without secondary SARS-CoV-2 infection. Results: During the 6-month survey, 1.78% seropositive subjects developed secondary SARS-CoV-2 infection while 6.63% seronegative controls developed primary infection (odds ratio: 0.26; 95% confidence interval: 0.17-0.38). Secondary infection was associated with low or absent serum neutralizing titer (p<0.01) and was mildly symptomatic in 45.8% cases vs 71.4% symptomatic primary infections (odds ratio: 0.34; 95% confidence interval: 0.16-0.78). Conclusions: Immunity from natural infection appears protective from secondary infection; therefore, vaccination of seronegative subjects might be prioritized.
2021
immune protection; neutralizing antibody; SARS-CoV-2 infection; secondary infection
Rovida, Francesca; Cassaniti, Irene; Percivalle, Elena; Sarasini, Antonella; Paolucci, Stefania; Klersy, Catherine; Cutti, Sara; Novelli, Viola; Marena, Carlo; Luzzaro, Francesco; De Vito, Giovanni; Schiavo, Roberta; Cascio, Giuliana Lo; Lilleri, Daniele; Baldanti, Fausto
File in questo prodotto:
Non ci sono file associati a questo prodotto.

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11383/2139481
 Attenzione

L'Ateneo sottopone a validazione solo i file PDF allegati

Citazioni
  • ???jsp.display-item.citation.pmc??? 12
  • Scopus 16
  • ???jsp.display-item.citation.isi??? 16
social impact