The latest Covid fad is the need for rapid saliva tests. Well, duh. If you could spit in a cup and get results in minutes, that would be good. It would be really nifty if we could have everyone testing on a continuous basis and quarantining only when needed. And, thus, I shall immediately call this into existence!
Waiting . . . . waiting . . . . waiting . . . .
Well, that didn’t work so well. The point is that sometimes the fact that we can imagine something doesn’t mean it can exist — at least not in the time frame we need it.
There are some saliva tests in development and they’d like someone to give them massive amounts of money. Well, hell, why not I suppose.
Here’s the problem with what we know about these tests so far — they’re not very “accurate” and they generate too many false positives.
The accuracy thing is where the trouble lies since “accuracy” isn’t the proper term — rather we should be talking about “sensitivity.” In other words, the higher the viral load you have, the better these things do in giving a “yep, this person has Covid-19.”
Some have suggested that this isn’t a huge problem because what you do is test, test, test, test, test and keep testing and then yell “we got one!” if you finally get a positive and this will solve the problem. Of course, what can also happen is that someone who’s feeling just a tad unwell infects a whole lot of people before getting that positive result. That would be bad. And, of course, we’re still basically clueless on asymptomatic transmission.
The thing of it is that the current saliva tests do not meet the criteria for FDA certification because they’re not sensitive enough. There is a hue and cry to simply relax the criteria. Maybe and hopefully people smarter than I am are looking at whether this makes sense although flipping a coin may be the only true scientific way to decide given past results.
False positives aren’t good either and there are a lot of ways this can go sideways. In 2001, Abbott Laboratories paid a $16.2 million jury award for a woman who received a false pregnancy test that led to an erroneous cancer diagnosis, chemotherapy, and a hysterectomy. So far false positives have only resulted in inconvenience and a limited amount of missed work. Whether there are other possible ramifications, we’ll know down the line.
So we’ll see but I’m not holding my breath that we’ll have a spit test that’s worth its salt anytime soon. Honestly, we should develop a spit test that gives a “+” every 5,000th test or so. That way everyone can get back to work and it would probably be just about as “sensitive.”