Letters: May 2021

Cloud-free distribution

As an octagenarian who has just received the second dose of the Pfizer vaccine, I was interested in the article on Asel Sartbaeva’s use of silica coats to stop vaccines spoiling at room temperature.

Many years ago I was involved in research into silica hydrogels to prevent cloudiness in lager beers when cooled. This led to the development of the commercial product Lucilite, which as far as I know is still in use today. This works by adsorbing the proteinaceous material that causes the cloudiness onto the silica, which could then be filtered out.

Although powderlike in appearance, these silica hydrogels contain up to 80% water. An alternative line of research showed that such hydrogels could be tabletted or extruded under pressure and dried if necessary, leaving the silica matrix intact and stable.

It struck me this could be investigated to see if such stable and inorganic silica hydrogels might be used as carriers to provide vaccines cheaply and safely to poorer parts of the world.

Tom Griffiths FRSC
Via email