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

Abstract

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.

Keywords: Infection control; SARS-CoV-2 asymptomatic infection; SARS-CoV-2 surveillance.

Fig 1

Phylogenetic tree of SARS-CoV-2 detected in samples of nasopharyngeal secretion (n = 59) from health care professionals at the PUC-Campinas hospital from May 2020, to September 2020. Cluster C, both nursing technicians in the COVID ward collected on the same day (June 19); cluster H, cleaning staff in the COVID ward collected on June 22 and 29.

Fig 2

Temporal trend of weekly rates of absence from work by COVID-19. In PUC-Campinas Hospital, epidemiological weeks 1-37, 2020. *APC refers to weekly percent variation of rates, which are significantly different from zero at alpha = 0.05.

Fig 3

Absence of health professionals for all causes at Hospital PUCC, Campinas. (A) Temporal trend of absence from work from March 2019 to August 2019 and 2020. (B) Daily absenteeism (median and first and third quartiles) for all causes from January 1, 2019, to August 30, 2019, and 2020.

Fig 4

Health care-related COVID-19 by epidemiological weeks from the intervention (week 20). At hospital PUC-Campinas, 2020. *Dotted line, moving average, interval 2 (weeks).