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9 páginas, 5 figuras, 1 tabla, Studies investigating the cumulative incidence of and immune status against SARS-CoV-2 infection provide valuable information for shaping public health decision-making. A cross-sectional study on 935 participants, conducted in the Valencian Community (VC), measuring anti-SARS-CoV-2-receptor binding domain-RBD-total antibodies and anti-Nucleocapsid (N)-IgGs via electrochemiluminescence assays. Quantitation of neutralizing antibodies (NtAb) against ancestral and Omicron BA.1 and BA.2 variants and enumeration of SARS-CoV-2-S specific-IFNγ-producing CD4+ and CD8+ T cells was performed in 100 and 137 participants, respectively. The weighted cumulative incidence was 51.9% (95% confidence interval [CI]: 48.7-55.1) and was inversely related to age. Anti-RBD total antibodies were detected in 97% of participants; vaccinated and SARS-CoV-2-experienced (VAC-ex; n = 442) presented higher levels (p < 0.001) than vaccinated/naïve (VAC-n; n = 472) and nonvaccinated/experienced (UNVAC-ex; n = 63) subjects. Antibody levels correlated inversely with time elapsed since last vaccine dose in VAC-n (Rho, -0.52; p < 0.001) but not in VAC-ex (rho -0.02; p = 0.57). Heterologous booster shots resulted in increased anti-RBD antibody levels compared with homologous schedules in VAC-n, but not in VAC-ex. NtAbs against Omicron BA.1 were detected in 94%, 75%, and 50% of VAC-ex, VAC-n and UNVAC-ex groups, respectively. For Omicron BA.2, the figures were 97%, 84%, and 40%, respectively. SARS-CoV-2-S-reactive IFN-γ T cells were detected in 73%, 75%, and 64% of VAC-ex, VAC-n and UNVAC-ex, respectively. Median frequencies for both T-cell subsets were comparable across groups. In summary, by April 2022, around half of the VC population had been infected with SARS-CoV-2 and, due to extensive vaccination, displayed hybrid immunity., Eliseo Albert (Juan Rodés Contract; JR20/00011) Estela Giménez (Juan Rodés Contract, JR18/00053) and Ignacio Torres (Río Hortega Contract; CM20/00090) hold contracts funded by the Carlos III Health Institute (co‐financed by the European Regional Development Fund, ERDF/FEDER). Ron Geller holds a Ramon y Cajal fellowship from the Spanish Ministry of Economics and Competitiveness (RYC‐2015‐17517). This work was supported in part by the European Commission NextGenerationEU fund, awarded to RG and IC through CSIC's Global Health Platform (PTI Salud Global).

A third Comirnaty® vaccine dose increased SARS-CoV-2-receptor binding domain antibody levels (median of 93-fold) and neutralizing antibody titers against Wuhan-Hu-1 (median, 57-fold), Beta (median, 22-fold), Delta, (median, 43-fold) and Omicron (median, 8-fold) variants, particularly in SARS-CoV-2-naïve individuals, but had a negligible impact on S-reactive T-cell immunity in nursing home residents.

We investigated whether peripheral blood levels of SARS-CoV-2 Spike (S) receptor binding domain antibodies (anti-RBD), neutralizing antibodies (NtAb) targeting Omicron S, and S-reactive-interferon (IFN)-γ-producing CD4+ and CD8+ T cells measured after a homologous booster dose (3D) with the Comirnaty® vaccine was associated with the likelihood of subsequent breakthrough infections due to the Omicron variant. An observational study including 146 nursing home residents (median age, 80 years; range, 66-99; 109 female) evaluated for an immunological response after 3D (at a median of 16 days). Anti-RBD total antibodies were measured by chemiluminescent immunoassay. NtAb were quantified by an Omicron S pseudotyped virus neutralization assay. SARS-CoV-2-S specific-IFNγ-producing CD4+ and CD8+ T cells were enumerated by whole-blood flow cytometry for intracellular cytokine staining. In total, 33/146 participants contracted breakthrough Omicron infection (symptomatic in 30/33) within 4 months after 3D. Anti-RBD antibody levels were comparable in infected and uninfected participants (21 123 vs. 24 723 BAU/ml; p = 0.34). Likewise, NtAb titers (reciprocal IC50 titer, 157 vs. 95; p = 0.32) and frequency of virus-reactive CD4+ (p = 0.82) and CD8+ (p = 0.91) T cells were similar across participants in both groups. anti-RBD antibody levels and NtAb titers estimated at around the time of infection were also comparable (3445 vs. 4345 BAU/ml; p = 0.59 and 188.5 vs. 88.9; p = 0.70, respectively). Having detectable NtAb against Omicron or SARS-CoV-2-S-reactive-IFNγ-producing CD4+ or CD8+ T cells after 3D was not correlated with increased protection from breakthrough infection (OR, 1.50; p = 0.54; OR, 0.0; p = 0.99 and OR 3.70; p = 0.23, respectively). None of the immune parameters evaluated herein, including NtAb titers against the Omicron variant, may reliably predict at the individual level the risk of contracting COVID-19 due to the Omicron variant in nursing home residents., Ignacio Torres (Río Hortega Contract; CM20/00090), Estela Giménez (Juan Rodés Contract, JR18/00053), and Eliseo Albert (Juan Rodés Contract; JR20/00011) hold contracts funded by the Carlos III Health Institute (cofinanced by the European Regional Development Fund, ERDF/FEDER). Ron Geller holds a Ramon y Cajal fellowship from the Spanish Ministerio de Economía y Competitividad (RYC‐2015‐17517). This study work was supported by Instituto de Salud Carlos III, Madrid, Spain (FIS, PI21/00563) to David Navarro, and by the European Commission NextGenerationEU fund (EU 2020/2094), through CSIC's Global Health Platform (PTI Salud Global) to Ron Geller.

Severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) Delta variant break-through infections in nursing home residents following vaccination with Comirnaty®COVID‐19 vaccine were characterized. In total, 201 participants (median age, 87 years;range, 64–100; 133 female) from two nursing homes in the Valencian community (Spain)were included. SARS‐CoV‐2‐Spike (S) antibody responses were determined by a lateralflow immunocromatography (LFIC) assay and by quantitative electrochemiluminescentassay in LFIC‐negative participants. SARS‐CoV‐2‐S‐IFNγT cells were enumerated by flowcytometry in 10 participants. Nasopharyngeal SARS‐CoV‐2 RNA loads were quantified byreal‐time polymerase chain reaction assays. Vaccine breakthrough COVID‐19 due to theDelta variant occurred in 39 residents (median age, 87 years; range, 69–96; 31 female) ata median of 6.5 months after vaccination (nine requiring hospitalization). Breakthroughinfections occurred at a higher rate(p< 0.0001) in residents who had not been previouslyinfected with SARS‐CoV‐2 (naïve) (33/108; 18%) than in those with prior diagnosis ofSARS‐CoV‐2 infection (experienced) (6/93; 6.4%), and were more likely (p< 0.0001) todevelop in residents who tested negative by LFIC (20/49) at 3 months after vaccinationas compared to their LFIC‐positive counterparts (19/142). Among LFIC‐negativeresidents, a trend towards lower plasma anti‐RBD antibody levels was noticed in thosedeveloping breakthrough infection (p=0.16).SARS‐CoV‐2 RNA loads in nasopharyngealspecimens were lower in SARS‐CoV‐2‐experienced residents (p< 0.001) and in thosetesting positive by LFIC (p=0.13). The frequency of SARS‐CoV‐2‐S‐reactive T cells at3monthswassimilarinLFIC‐negative residents with (n=7) or without (n=3)breakthrough infection. Prior history of SARS‐CoV‐2 infection and detection ofS‐reactive antibodies by LFIC at 3 months is associated with a lower risk of Delta‐variant breakthrough infection in nursing home residents at midterm after Comirnaty®COVID‐19 vaccination., We are grateful to the Vice‐presidency and Ministry of Equality andInclusive Policies of the Valencia Community, the Corporate Associationof Residences and Services for People with Dependency of the ValencianCommunity (AERTE), the Valencia Health System nursing homedepartmental committees, and the staff and residents of the participantnursing homes for their collaboration in developing the ProVaVacprogram. We would also like to thank Ana Berenguer, General Directorof Analysis and Public Policies of the Presidency of the Generalitat.Ignacio Torres (Río Hortega Contract; CM20/00090) and Eliseo Albert(Juan Rodés Contract; JR20/00011) hold contracts funded by the HealthInstitute Carlos III (co‐financed by the European Regional DevelopmentFund, ERDF/FEDER). This study received no public or private funds.

SUMARIO : Encuentros temporales entre astronomía y prehistoria.-- Tercer año del proyecto Severo Ochoa del IAA.-- Deconstrucción. Visitantes interestelares.-- Historias...La máquina en el desierto.--El Moby Dick de...Antonio Claret (IAA-CSIC).-- Actualidad.-- Sala limpia.-- Pilares e incertidumbres., Este número ha contado con el apoyo económico de la Agencia Estatal de Investigación (Ministerio de Ciencia, Innovación y Universidades) a través de la acreditación de Centro de Excelencia Severo Ochoa para el Instituto de Astrofísica de Andalucía (SEV-2017-0709). La página web de esta revista ha sido financiada por la Sociedad Española de Astronomía (SEA).