RESUMO
BACKGROUND: Saliva is easily obtainable non-invasively and potentially suitable for detecting both current and previous SARS-CoV-2 infection, but there is limited evidence on the utility of salivary antibody testing for community surveillance. METHODS: We established 6 ELISAs detecting IgA and IgG antibodies to whole SARS-CoV-2 spike protein, to its receptor binding domain region and to nucleocapsid protein in saliva. We evaluated diagnostic performance, and using paired saliva and serum samples, correlated mucosal and systemic antibody responses. The best-performing assays were field-tested in 20 household outbreaks. RESULTS: We demonstrate in test accuracy (N = 320), spike IgG (ROC AUC: 95.0%, 92.8-97.3%) and spike IgA (ROC AUC: 89.9%, 86.5-93.2%) assays to discriminate best between pre-pandemic and post COVID-19 saliva samples. Specificity was 100% in younger age groups (0-19 years) for spike IgA and IgG. However, sensitivity was low for the best-performing assay (spike IgG: 50.6%, 39.8-61.4%). Using machine learning, diagnostic performance was improved when a combination of tests was used. As expected, salivary IgA was poorly correlated with serum, indicating an oral mucosal response whereas salivary IgG responses were predictive of those in serum. When deployed to household outbreaks, antibody responses were heterogeneous but remained a reliable indicator of recent infection. Intriguingly, unvaccinated children without confirmed infection showed evidence of exposure almost exclusively through specific IgA responses. CONCLUSIONS: Through robust standardisation, evaluation and field-testing, this work provides a platform for further studies investigating SARS-CoV-2 transmission and mucosal immunity with the potential for expanding salivo-surveillance to other respiratory infections in hard-to-reach settings.
If a person has been previously infected with SARS-CoV-2 they will produce specific proteins, called antibodies. These are present in the saliva and blood. Saliva is easier to obtain than blood, so we developed and evaluated six tests that detect SARS-CoV-2 antibodies in saliva in children and adults. Some tests detected antibodies to a particular protein made by SARS-CoV-2 called the spike protein, and these tests worked best. The most accurate results were obtained by using a combination of tests. Similar tests could also be developed to detect other respiratory infections which will enable easier identification of infected individuals.
RESUMO
CHG-based hygiene methods are often a component of daily hygiene bundles to prevent central line-associated blood stream infections (CLABSIs) in pediatric hematology-oncology patients; however, adherence with 2% CHG wipes was inconsistent within our institution, risking infection for immunocompromised patients. A new 4% CHG foam method offers an alternative and is applied while bathing, as opposed to wipes used 1 h after bathing. An initial cohort of 24 high-risk oncology and bone marrow transplant (BMT) patients agreed to use 4% CHG foam in place of wipes, and then answered surveys to describe their experiences. Ninety-two percent preferred foam over wipes and were more likely to use the foam moving forward. CHG foam was then made available as an option to all patients in need of central line care upon admission to the hospital. Hygiene bundles in the electronic medical record were reviewed to measure baseline adherence rates. Random audits by nursing administration prospectively assessed CHG adherence. CLABSI data were collected prospectively with routine quality metric reports. Results were analyzed using run charts and u-charts, respectively. Hematology-Oncology unit adherence rates remained at a higher rate of adherence, and BMT unit adherence rates increased from an average of 55%-81.6% (p < 0.001). Primary CLABSIs remained rare events (average <1/1000 CVL days). On cost analysis, utilizing CHG foam results in an annual savings estimate of $40,000 for a 24-bed unit. In conclusion, 4% CHG foam provides a cost-effective and patient-preferred option for daily hygiene that maintains CLABSI preventative efforts.
