Lateral flow tests (LFT)

Lateral flow tests (also known as lateral flow assays, or lateral flow immunoassays, LFTs or LFDs - lots of synonyms!).  We have all been doing these tests regularly for ages, picking them up from work or getting them through the post (which has got trickier, getting messages about how there are no more home deliveries available today).  I know how to do a test - although it changed from throat and nose to just nose, at some point, and some details about stirring the swab in the reagent changed as well.

But how do they work?

Finding details on the general internet seems tricky - lots of items about where to get one, how to do the test, news stories about how effective they are, and pages from the companies that make them (order some now!).

Here are some things that give some detail.   Links marked with a * are for University of Leicester access - if you are at another institution or in the NHS you can get details from your librarian about how to access.    

Helbert, Immunology for Medical Students*, chapter 5, has an explanation of how lateral flow tests work, although in the context of pregnancy testing.   I assume the way the COVID LFT works is the same, but that it is detecting a different antigen.     

ELISA: Methods and Protocols* (Methods in Molecular Biology vol. 1318, edited by Robert Hnasko), has a chapter on lateral flow immunoassay.     

NICE Evidence Search (soon to be closed, disappointingly, and here is a petition to ask for it to be saved) has a lot about the roll out of LFTs in the NHS, and some studies of how effective they are.

There is also this from Science Direct* and this from The Vaccines Alliance, about the utility of LFTs in a global setting, but it does include a little about how they work.  

Or (late addition), if you want to watch something, the first in Jonathan Van-Tam's Royal Institution Christmas Lectures about viruses has an explanation of how LFTs work (link is to the BBC iPlayer so may work only in the UK).