A cure for Covid may arrive faster than a vaccine

A striking feature of Covid-19 is how medieval our response has had to be. Quarantine was the way people fought plagues in the distant past. We know by now that it will take many months to get a vaccine, whose job is to prevent you getting the disease. But what about a cure once you have caught it: why is there no pill to take? The truth is that, advanced as medical science is, we are mostly defenceless against viruses. There is no antiviral therapy to compare with antibiotics for treating bacteria.

Arguably, virology in 2020 is where bacteriology was in the 1920s. At the time, most of the experts in that field — including Alexander Fleming and his mentor, the formidable Sir Almroth Wright (nicknamed Sir Always Wrong by his foes) — thought a chemical therapy that killed bacteria without harming the patient was a wild goose chase. Instead, they argued, theway to fight bacteria was to encourage the body’s immune system. ‘Stimulate the phagocytes!’ was the cry of Wright’s semi-fictional avatar Sir Colenso Ridgeon in George Bernard Shaw’s play The Doctor’s Dilemma (referring to white blood cells). Vaccines should be used to treat as well as prevent infections, thought Wright and Fleming. Fleming then turned this theory upside down with his discovery of penicillin in 1928.

There are two reasons for this failure to have anything on the shelf that can be used to treat viruses: one biological, the other economic. The biological problem, as Amesh Adalja of Johns Hopkins University argued in a prescient call to arms just before the pandemic struck, is that viruses do not have their own biochemistry, because they borrow ours.

So unlike, say, tuberculosis, there is not much to attack. As any doctor will tell you, antibiotics are no use in fighting a virus. They interfere with machinery found only in bacteria, but there is no equivalent machinery in viruses — which are just a bunch of genes (15 of them in the case of Sars-CoV-2) that borrow our body’s machinery to replicate themselves.