A third way to design these icons is to decide the negative-space symbol first, before drawing any surrounding silhouette, reversing the usual order of drawing a figure and then cutting a symbol out of it.
For each new ward, start by drawing just the identifying symbol on its own: a small virus-like spiky shape for COVID-19, a ribbon loop for Cancer, a simplified toy block or small figure for Paediatric, and a rounded belly curve for Maternity.
Once that symbol shape is fixed, build a human silhouette around it, treating the symbol as a fixed cutout that the body silhouette has to accommodate, rather than drawing a generic body first and hunting for space to fit a symbol in afterward.
This order forces the silhouette's proportions to adjust icon by icon so the symbol always sits clearly and legibly in the centre of the chest area, matching how the original Cardiology and Neurology icons appear to have been built around their own central symbols.
After each icon is built this way, test it in isolation at a small size, away from the other icons, to check that the negative-space symbol alone is still recognisable even without any context.
Finally, place the new icon next to the original six and confirm the black silhouette style, stroke weight, and centred composition all still match.
Designing the cutout first and the body second keeps the meaning of each icon as clear as possible, since the identifying symbol is never an afterthought squeezed into leftover space.