I have a friend who is a proper scientist. You know the type, PhD after their name, and understands all the stats stuff like Cronbach’s alpha, Spearman’s r and the Wilcoxon Rank Sum test. Their area of research was water quality and they spent 3 years gathering data from the outfall from sewage works. Three years collecting dirty water samples and theirs is the prefix of doctor and the suffix PhD.

Collecting waste water has become a bit of a trend during the Covid pandemic. The BBC reported that fragments of the virus’ genetic material can be identified from sewage, even when there are only asymptomatic cases in the area. Identification is not easy because of other contaminants but clusters of infection may then be identified before symptomatic cases appear and preventive strategies targeted earlier than would otherwise be possible.

And if the virus is shed from one end of the gastro-intestinal tract, then it’s almost certainly at the other end too. We know that the virus gets up your nose and gathers round your tonsils. Never in the field of public health, has so much sneezing and gagging gone on in the bathrooms of this country as we test, test, test, desperately hoping for that single pink line to appear on the test kit. But what about that fluid that dentists spend their time fighting against? What about saliva?

There have been multiple research papers published in the past months, about the link between saliva and Covid, many fast tracked for dissemination in the fight against the disease. A recent study from the US confirmed that the virus was present in the saliva of both asymptomatic and pre-symptomatic patients. A quite specific review suggests that as saliva is easy to collect and saves the need for swabs-on-sticks-up-the-nose, which are uncomfortable and pose a risk of bleeding in some cases, then saliva testing for evidence of the presence of COVID-19 might be a more acceptable test mechanism. The review found that passively collected saliva had a high sensitivity rate to detect Covid in asymptomatic and mildly symptomatic patients when compared to naso-pharyngeal swabs. Passive collection – drooling, basically – means there is no contamination of the saliva from coughing or nasal discharge.

So there’s Covid in spit – who knew? All those prevention strategies for aerosol generating procedures must have been worth it.  But as the Government appears to remove all restrictions to normal life, how long before all those restrictions on dentistry are removed? Abandoned to the whims and fancies of the asymptomatic, untested – ‘it costs money, guv’ – maskless patient. Do we assume everyone is Covid positive, just as the basis of universal precautions is that everyone carries HIV or Hepatitis C? Back to normal then, with current screening depending largely on questions regarding symptoms and test results.

When carriers of Covid can be asymptomatic and there’s no longer testing freely available, questions about symptoms and test results appear to have limited use. There may be a future for a simple saliva test, to check what precautions are necessary before treating any patient. But I suspect that would be considered discriminatory and ethically unacceptable.

What then can be added to the standard procedures to help prevent spread of Covid? A pre-operative mouthrinse reduces the viral load in saliva for between 15 and 45 minutes. Maybe a 30 second swish of Chlorhexidene or hydrogen peroxide will become the norm for everyone.

Rubber dam is of course another weapon in the armoury of the dentist to reduce contaminated aerosols in the surgery Those of us of a certain age will recall the enthusiasm of Keith Marshall’s ‘Dam it, its easy’ courses. There’s surely an opportunity here for an entrepreneurial educator to set up some hands-on dam refresher courses.

And since condom sales fell by 40% during lockdown, there may be some good opportunities for sponsorship from manufacturers as they seek alternative outlets for their rubber. Presumably there will be fewer contaminants in the wastewater, too.