Ethics and consent
The ethical review committee of the Charité university hospital in Berlin approved the present study under the reference number EA2/126/17. All custodians gave written consent for the inclusion of their child into the study.
CT and ND are the directors of SpOtOn Clinical Diagnostics Limited. YD is named on the patent for the method referred to in the manuscript but has received no financial benefit. The other authors declare no conflict of interest.