Should we be spraying surfaces, and ourselves, with an off-the-shelf mosquito repellent to tackle the spread of Covid-19? The Ministry of Defence has revealed that it has been issuing soldiers with Mosi-guard natural, a spray derived from eucalyptus oil and manufactured by a small company called Citrefine, in Leeds, from the beginning of the Covid crisis. The spray has been tested by the Defence Science and Technology Laboratory and found to have a rapid effect on reducing levels of the virus when sprayed onto surfaces. It did not, however, succeed in eliminating the virus altogether.

In one test, the product was sprayed onto latex synthetic skin an hour before being exposed to SARS-CoV-2, the virus which causes Covid-19. Four hours later, levels of the virus were found to be only one hundredth of what they were on a surface which hadn’t been sprayed with the product. However, the virus did not fall below detectable levels. The research has not been published in a peer-reviewed scientific journal, but its findings have been put online by the Ministry of Defence.

The active ingredient in Mosi-guard Natural was found to be Citriodiol, a product made from hydrated oil of the lemon eucalyptus. The product will be welcomed as part of the armoury of substances which have been used to try to protect surfaces from the spread of SARS-CoV-2. What we still don’t know, however, is the extent to which the virus is being spread via contact with infected surfaces and how much is being spread through the air, directly from infected people via aerosols and larger droplets. Better data on how the virus spreads would help inform issues such as social distancing, decontamination of trains, buses and other public environments.<//>