ABSTRACT
Background. The need for community surveillance of respiratory viruses in high-risk settings such as homeless shelters has been underscored by the COVID-19 pandemic. Here, we show that sampling high-touch surfaces is a low-cost, minimally intensive means of community respiratory virus surveillance. Methods. Environmental samples were collected weekly from adult and family homeless shelters in King County, WA from November 2019 - April 2020. At times when residents were present, a 10cm2 area of selected high-touch surfaces were swabbed and bioaerosol samples were collected in high-traffic areas. Surfaces included entrance and restroom doorknobs, counters, and surfaces unique to each shelter. Study staff collected mid-turbinate swabs from shelter resident participants aged > 3 months with symptoms of acute respiratory illness (ARI). All samples were tested by RT-PCR for 27 viruses. From January 1, 2020 onward, samples were also tested for SARS-CoV-2. Results. A total of 788 environmental swabs, 1509 nasal swabs, and 98 bioaerosol samples from 6 adult and 3 family shelters were tested. Adenovirus (109 positive swabs, 13.8% of tested swabs), rhinovirus (107, 13.6%) and human bocavirus (62, 7.9%) were the most frequently detected viruses in surface swabs. Rhinovirus (160, 10.6%), human coronaviruses (79, 5.24%) and influenza B (43, 2.85%) were the most detected in nasal swabs. All viruses detected in nasal swabs were found in surface swabs. Of 9 surfaces, exterior bathroom doorknobs were the physical location with the highest number of pathogens detected. SARS-CoV-2 was first detected in surface swabs on 3/20/20, and in nasal swabs on 3/10/20. Bioaerosol samples detected virus in a low percentage of samples relative to surface and nasal swabs. Table 1 Count and period prevalence of environmental viral detection by shelter type, November 18, 2019 - April 10, 2020. (Figure Presented) Conclusion. Respiratory viruses detected through environmental sampling in homeless shelters were similar to the viruses detected from ARI episodes in study participants. Environmental surface sampling presents a plausible, minimally invasive method of surveillance for both endemic and emerging respiratory pathogens, as evidenced by the detection of SARS-CoV-2 during the early stages of the pandemic. Further research could focus on sampling public locations for broader community surveillance and culturing viruses found on these surfaces.
ABSTRACT
Background. Human parainfluenza viruses (HPIV) cause respiratory illness in individuals of all ages. However, HPIV epidemiology data in people experiencing homelessness (PEH) are limited. Methods. We analyzed cross-sectional data from a clinical trial and SARS-CoV-2 surveillance study in 23 homeless shelters in King County, Washington from October 2019-May 2021. Questionnaires and nasal swab specimens were obtained from eligible participants at enrollment. Between October 2019-March 31, 2020, participants included those aged > 3 months with acute respiratory illness. Monthly shelter surveillance was also conducted where participants were recruited regardless of symptoms. With the community spread of SARS-CoV-2, the study design transitioned from a clinical trial to a SARS-CoV-2 surveillance study which expanded enrollment eligibility to include participants with or without symptoms from April 1, 2020, onward. Participants were not followed longitudinally but were permitted to enroll multiple times during the study period. Specimens were tested for HPIV 1-4 and other respiratory viruses using RT-PCR. Results. Among 14,464 specimens, 32 were HPIV-positive from 29 participants (median age 9 years, range 0.3-64 years;45% female;28% Black;10% with chronic conditions) of which 59% were children. Family shelters had the highest percentage of HPIV infections (Table). HPIV was detected every month before the community spread of SARS-CoV-2. All HPIV-positive samples in May 2021 came from a single family shelter (Figure). Only 67% of HPIV-positive participants had symptoms with runny nose, cough and sore throat the most commonly reported. HPIV codetection with other respiratory viruses occurred in 19% of HPIV-positive specimens;Rhinovirus co-detection (16%) was the most common. Human Parainfluenza Encounters by Shelter Type Before and After April 1, 2020 Human Parainfluenza Positive Samples by Shelter Type Among Unique Participants Conclusion. HPIV affected PEH of all ages with most cases in shelters with children. Coinciding with community-wide SARS-CoV-2 mitigation efforts, the number of HPIV infections were reduced. However, a cluster of HPIV infections still occurred within one family shelter. Shelter-specific public health measures including nonpharmaceutical interventions used during the COVID-19 pandemic may reduce HPIV infections among residents.