Outbreaks of SARS-CoV-2 Infections in Nursing Homes during Periods of Delta and Omicron Predominance, United States, July 2021-March 2022.

SARS-CoV-2 infections among vaccinated nursing home residents increased after the Omicron variant emerged. Data on booster dose effectiveness in this population are limited. During July 2021-March 2022, nursing home outbreaks in 11 US jurisdictions involving >3 infections within 14 days among residents who had received at least the primary COVID-19 vaccine(s) were monitored. Among 2,188 nursing homes, 1,247 outbreaks were reported in the periods of Delta (n = 356, 29%), mixed Delta/Omicron (n = 354, 28%), and Omicron (n = 536, 43%) predominance. During the Omicron-predominant period, the risk for infection within 14 days of an outbreak start was lower among boosted residents than among residents who had received the primary vaccine series alone (risk ratio [RR] 0.25, 95% CI 0.19-0.33). Once infected, boosted residents were at lower risk for all-cause hospitalization (RR 0.48, 95% CI 0.40-0.49) and death (RR 0.45, 95% CI 0.34-0.59) than primary vaccine-only residents.

Assessments and observations of infection prevention and control practices in US outpatient hemodialysis facilities, 2015-2018: important opportunities for improvement.

Infections cause substantial morbidity and mortality among patients receiving care in outpatient hemodialysis facilities. We describe comprehensive infection prevention assessments by US public health departments using standardized interview and observation tools. Results demonstrated how facility layouts can undermine infection prevention and that clinical practices often fall short of policies.

Severe acute respiratory coronavirus virus 2 (SARS-CoV-2) outbreaks in nursing homes involving residents who had completed a primary coronavirus disease 2019 (COVID-19) vaccine series-13 US jurisdictions, July-November 2021.

Among nursing home outbreaks of coronavirus disease 2019 (COVID-19) with ≥3 breakthrough infections when the predominant severe acute respiratory coronavirus virus 2 (SARS-CoV-2) variant circulating was the SARS-CoV-2 δ (delta) variant, fully vaccinated residents were 28% less likely to be infected than were unvaccinated residents. Once infected, they had approximately half the risk for all-cause hospitalization and all-cause death compared with unvaccinated infected residents.

Chromosomal instability and delayed apoptosis in long-term T-lymphocyte cultures irradiated with carbon ions and x rays.

In this study, we examined genomic instability induced by 250 kV X rays and 100 MeV/nucleon carbon ions in long-term lymphocyte cultures from two healthy donors. Two biological end points, delayed apoptosis and chromosomal instability, were studied in descendants of cells irradiated with three different doses of the particular radiation up to 22 population doublings. The delayed apoptosis showed no clear dependence on radiation dose, culture time or radiation quality. A persistent significant increase in the rate of apoptosis up to 36 days after X irradiation was observed for a dose of 4 Gy in donor 1 only. For both donors and radiations, de novo aberration yields were significantly increased in comparison to control values up to day 36. For both radiations, chromosome-type aberrations were seen more frequently than chromatid-type aberrations in both donors up to 22 days postirradiation. In both donors, carbon ions were more effective than X rays with respect to the induction of chromosome instability. A dose of 0.25 Gy of carbon ions corresponding to 1.4 ion traversals per cell nucleus was effective in the induction of instability in our cell system.

The effect of wortmannin on radiation-induced chromosome aberration formation in the radioresistant tumor cell line WiDr.

We analyzed the formation of radiation-induced chromosome aberrations in the cells of the radioresistant colon carcinoma cell line WiDr after treatment with wortmannin, an inhibitor of PI-3 kinases, including DNA-PK. Cells irradiated in G0/G1 phase with 200 kV X rays were treated with wortmannin before or after irradiation. Chromosome-type and chromatid-type aberrations were scored in metaphase cells by either Giemsa staining or FISH. Moreover, DNA-PK activity was measured in the absence and presence of wortmannin. In irradiated G0/G1-phase WiDr cells, only chromosome-type aberrations, including simple and complex exchanges and excess acentrics, were observed. After addition of 1 to 20 microM wortmannin, the formation of chromosome-type exchange aberrations was completely suppressed. The irradiated cells displayed exclusively chromatid-type aberrations including simple and complex chromatid exchanges and chromatid/isochromatid breaks. Whether the chromatid-type aberrations arise during G0/G1 as a result of homologous recombination processes coping with damaged DNA or whether DNA damage induced during G0/G1 phase persists until S and G2 phase and is then processed by homologous recombination pathways must be investigated further.

Combined effect of topotecan and irradiation on the survival and the induction of chromosome aberrations in vitro.

BACKGROUND: Topotecan demonstrated radiosensitizing effects in vivo and in vitro, which are schedule- and cell line dependent. The underlying mechanisms are not fully understood. Topotecan interferes with DNA replication, transcription, and repair and may thus increase the frequency of radiation-induced lethal chromosome aberrations. MATERIAL AND METHODS: U-373 MG glioblastoma cells, WiDr colon adeno-carcinoma cells, as well as normal human fibroblasts and lymphocytes were irradiated (0-6 Gy) and exposed to varying topotecan doses (0.01-10 microM) always 15 minutes before and either 1 hour after (short-term) or 24 hours after (long-term) irradiation. Survival was measured by colony-forming assays, and chromosome aberrations were scored in Giemsa-stained metaphase spreads. Unirradiated cells served as specific controls. RESULTS: Topotecan alone reduced the clonogenic cell survival in a concentration- and time-dependent manner, and radiosensitization was observed for all cell lines tested. There was no correlation between clonogenic cell survival and the frequencies of treatment-induced chromosomal aberrations, neither in tumor cells nor in fibroblasts. In contrast, in lymphocytes increased frequencies of radiation-induced dicentric chromosomes were seen after the combined treatment. CONCLUSION: In certain cell types combined radiation/topotecan treatment may lead to increased frequencies of lethal chromosome aberrations. However, there is no evidence that the increased formation of lethal chromosome aberrations plays an important role in the topotecan-induced radiosensitization of human tumors.