Understanding the particle size distribution in the air and patterns of environmental contamination of SARS-CoV-2 is essential for infection prevention policies. Here we screen surface and air samples from hospital rooms of COVID-19 patients for SARS-CoV-2 RNA. Environmental sampling is conducted in three airborne infection isolation rooms (AIIRs) in the ICU and 27 AIIRs in the general ward. 245 surface samples are collected. 56.7% of rooms have at least one environmental surface contaminated. High touch surface contamination is shown in ten (66.7%) out of 15 patients in the first week of illness, and three (20%) beyond the first week of illness (p = 0.01, χ2 test). Air sampling is performed in three of the 27 AIIRs in the general ward, and detects SARS-CoV-2 PCR-positive particles of sizes >4 µm and 1–4 µm in two rooms, despite these rooms having 12 air changes per hour. This warrants further study of the airborne transmission potential of SARS-CoV-2.

Background The performance of rRT-PCR for SARS-CoV-2 varies with sampling site(s), illness stage and infection site. Methods Unilateral nasopharyngeal, nasal mid-turbinate, throat swabs, and saliva were simultaneously sampled for SARS-CoV-2 rRT-PCR from suspect or confirmed cases of COVID-19.True positives were defined as patients with at least one SARS-CoV-2 detected by rRT-PCR from any site on the evaluation day or at any time point thereafter, till discharge. Diagnostic performance was assessed and extrapolated for site combinations. Results We evaluated 105 patients; 73 had active SARS-CoV-2 infection. Overall, nasopharyngeal specimens had the highest clinical sensitivity at 85%, followed by throat, 80%, mid-turbinate, 62%, and saliva, 38-52%. Clinical sensitivity for nasopharyngeal, throat, mid-turbinate and saliva was 95%, 88%, 72%, and 44-56% if taken ≤7 days from onset of illness, and 70%, 67%, 47%, 28-44% if >7 days of illness. Comparing patients with URTI vs. pneumonia, clinical sensitivity for nasopharyngeal, throat, mid-turbinate and saliva was 92% vs 70%, 88% vs 61%, 70% vs 44%, 43-54% vs 26-45%. A combination of nasopharyngeal plus throat or mid-turbinate plus throat specimen afforded overall clinical sensitivities of 89-92%, this rose to 96% for persons with URTI and 98% for persons <7 days from illness onset. Conclusion Nasopharyngeal followed by throat specimens offer the highest clinical sensitivity for COVID-19 diagnosis in early illness. Clinical sensitivity improves and is similar when either mid-turbinate or nasopharyngeal specimens are combined with throat specimens. Upper respiratory specimens perform poorly if taken after the first week of illness or if there is pneumonia.

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We investigate the spreading of SARS-CoV-2 in the state of Alagoas, northeast of Brazil, via an adaptive susceptible-infected-removed (SIR) model featuring dynamic recuperation and propagation rates. Input parameters are defined based on data made available by Alagoas Secretary of Health from April 19, 2020 on. We provide with the evolution of the basic reproduction number [Formula: see text] and reproduce the historical series of the number of confirmed cases with less than [Formula: see text] error. We offer predictions, from November 16 forward, over the epidemic situation in the near future and show that it will keep decelerating. Furthermore, the same model can be used to study the epidemic dynamics in other countries with great easiness and accuracy.

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