Asymptomatic cases and limited transmission of SARS-CoV-2 in residents and healthcare workers in three Dutch nursing homes
Abstract
Purpose
Many nursing homes worldwide have been hit by outbreaks of the new severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We aimed to assess the contribution of a- and presymptomatic residents and healthcare workers in transmission of SARS-CoV-2 in three nursing homes.
Methods
Two serial point-prevalence surveys, 1 week apart, among residents and healthcare workers of three Dutch nursing homes with recent SARS-CoV-2 introduction. Nasopharyngeal and oropharyngeal testing for SARS-CoV-2, including reverse-transcriptase polymerase chain reaction (rRT-PCR) was presymptomatic or asymptomatic with standardized symptom assessment.
Results
In total, 297 residents and 542 healthcare workers participated in the study. At the first point-prevalence survey, 15 residents tested positive of which one was presymptomatic (Ct value>35) and three remained asymptomatic (Ct value of 23, 30 and 32). At the second point-prevalence survey one resident and one healthcare worker tested SARS-CoV-2 positive (Ct value >35 and 24, respectively) and both remained asymptomatic.
Conclusion
This study confirms a-and presymptomatic occurrence of Covid-19 among residents and health care workers. Ct values below 25 suggested that these cases have the potential to contribute to viral spread. However, very limited transmission impeded the ability to answer the research question. We describe factors that may contribute to the prevention of transmission and argue that the necessity of large-scale preemptive testing in nursing homes may be dependent of the local situation regarding prevalence of cases in the surrounding community and infection control opportunities.
KEY SUMMARY POINTS
Aim
To assess the contribution of a- and presymptomatic residents and healthcare workers in transmission of SARS-CoV-2 in three nursing homes by facility wide preemptive testing.
Findings
Occurrence of a-and presymptomatic residents and healthcare workers with Ct values below 25 was confirmed. However, evaluation of contribution to transmission of the virus was not possible because of limited positive cases in the follow-up.
Message
Necessity of large-scale preemptive testing for a- and presymptomatic SARS-CoV-2 cases in nursing homes may be dependent on prevalence of cases in the surrounding community and infection control opportunities.
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