Article Publish Status: FREE
Abstract Title:

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-controlled study.

Abstract Source:

Int J Infect Dis. 2021 Jul 7 ;109:199-202. Epub 2021 Jul 7. PMID: 34242763

Abstract Author(s):

Francesca Rovida, Irene Cassaniti, Elena Percivalle, Antonella Sarasini, Stefania Paolucci, Catherine Klersy, Sara Cutti, Viola Novelli, Carlo Marena, Francesco Luzzaro, Giovanni De Vito, Roberta Schiavo, Giuliana Lo Cascio, Daniele Lilleri, Fausto Baldanti

Article Affiliation:

Francesca Rovida


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.

Study Type : Human Study

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Sayer Ji
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