Impact of COVID-19 RT-PCR testing of asymptomatic health care workers on absenteeism and hospital transmission during the pandemic.

BACKGROUND: Reducing the transmission of SARS-CoV-2 from asymptomatic and pre-symptomatic patients is critical in controlling the circulation of the virus. METHODS: This study evaluated the prevalence of Reverse transcription polymerase chain reaction (RT-PCR) positivity in serial tests in 429 asymptomatic health care workers (HCW) and its impact on absenteeism. HCW from a COVID-19 reference hospital were tested, screened, and placed on leave. A time-series segmented regression of weekly absenteeism rates was used, and cases of infection among hospitalized patients were analyzed. Viral gene sequencing and phylogenetic analysis were performed on samples from HCW who had a positive result. RESULTS: A significant decrease in absenteeism was detected 3-4 weeks after the intervention at a time of increased transmission within the city. The prevalence of RT-PCR positivity among asymptomatic professionals was 17.3%. Phylogenetic analyses (59 samples) detected nine clusters, two of them strongly suggestive of intrahospital transmission with strains (75% B.1.1.28) circulating in the region during this period. CONCLUSIONS: Testing and placing asymptomatic professionals on leave contributed to control strategy for COVID-19 transmission in the hospital environment, and in reducing positivity and absenteeism, which directly influences the quality of care and exposes professionals to an extra load of stress.

Genetic diversity and HIV-1 incidence estimation among cocaine users in São Paulo, Brazil.

We describe HIV-1 incidence and the prevalence of genetic subtypes among cocaine users in São Paulo, Brazil. A cross-sectional HIV-1 survey was carried out among 839 current cocaine users attending seven drug treatment units in the São Paulo metropolitan area from 1997 to 1998. HIV-1 subtyping was performed among 41 positive individuals using the heteroduplex mobility assay and DNA sequencing. Participants were mainly male (95.7%) with a history of previous imprisonment (54%), and the mean age was 26.9 years (SD = 7.2). The majority (64.4%) were current crack cocaine users, and 82.1% of the total participants were noninjectors. HIV-1 seroprevalence was 4.9% (95% confidence interval [CI], 3.6%-6.6%), and the incidence (estimated by the sensitive/less-sensitive immunoassay testing strategy) was 0.71% per year (95% CI, 0.07-3.03). HIV-1 subtype B was predominant (90.3%), followed by subtype F. There was no statistically significant association between HIV-1 subtype and specific route of drug administration. Our incidence data show evidence of recent HIV-1 transmission among cocaine users, mainly among noninjectors. Detection of recently infected HIV-1 cases linked to genetic diversity analysis may provide baseline information for public health interventions in this sentinel group.