Outbreak of SARS-CoV-2 B.1.617.2 (Delta) variant in a Nursing Home 28 weeks after two doses of mRNA anti-Covid-19 vaccines: evidence of a waning immunity
| Autor: | Monica Gennari, Gianfranco Brambilla, De Antoni Mario Ernesto, Alessandra Dal Zotto, Liviano Vianello, Francesca Russo, Antonio Di Caprio, Alice Pierobon, Antonio Antico, Mario Saugo |
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| Rok vydání: | 2021 |
| Předmět: |
Microbiology (medical)
COVID-19 Vaccines Coronavirus disease 2019 (COVID-19) Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Antibodies Viral Disease Outbreaks symbols.namesake NursingHome Humans Medicine RNA Messenger Waning immunity Index case Fisher's exact test Vaccine effectiveness Vaccines Synthetic SARS-CoV-2 business.industry Vaccination COVID-19 Outbreak General Medicine anti-Spike IgG immunity Nursing Homes Research Note Titer B.1.617.2SARS-CoV-2 variant Infectious Diseases Immunology symbols mRNA Vaccines business Nursing homes |
| Zdroj: | Clinical Microbiology and Infection |
| Popis: | ObjectivesDescription of a SARS-CoV-2 B.1.617.2 (Delta) variant outbreak among residents (N=69) and Health Workers (HWs: N=69) of a small Nursing Home in Northern-East Italy, with full vaccination coverage of 91 and 82%, respectively. Evaluation of the Anti-Spike IgG titers 28 weeks after the mRNA vaccine boosts against SARS-COV-2 infection and severe Covid-19.Materials and methodsA timely collection of sera within 48h from the index case; anti-Spike IgG determination (expressed as Binding Antibody Units – BAU/mL) through a commercial quantitative assay; SARS-CoV-2 diagnostics via RT-PCR, and full-genome sequencing for lineage characterization. Residents were grouped according to anti-Spike IgG titers (≤ 50, 51-1000, and > 1000 BAU/mL) and resulting protection against the infection and the severe disease was measured.Results0/20 HWs and 14/59 (24%) residents fully vaccinated and without a previous SARS-CoV-2 infection showed anti-Spike IgG lower/equal to 50 BAU/mL (1-sided Fisher exact p=0.011). Among these residents, a level of anti-Spike IgG ≤50 BAU/mL resulted in a higher risk of SARS-CoV-2 infection (RR=1.55, CI95% 1.17-2.05) and severe Covid-19 disease (RR=5.33, CI95% 1.83-15.57). Conclusion Low levels of SARS-CoV-2 neutralizing anti-Spike IgG in serum 28 weeks after the administration of the second dose parallels the waning of vaccine protection. |
| Databáze: | OpenAIRE |
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