It is no miracle cure. but president donald trumps enthusiasm for antibody cocktails is better grounded than some of his other medical endorsements. early trial results for the drugs, which mimic the bodys natural defences against covid-19, are promising. frontrunners regeneron and eli lilly can hope for a boost to their reputation and, to a lesser extent, their profits.

Normally, us regulators would insist on more proof of effectiveness but there is a good chance they will give the go-ahead for emergency use quickly. they are familiar with this class of drugs, called monoclonal antibodies, which have delivered big advances against diseases from asthma to cancer.

Shares of regeneron and eli lilly rose after mr trumps endorsement. each company could rake in about $1.5bn next year from sales of the antibodies, estimates bernstein. success would move the dial more for regeneron, which is less than half the size of eli lilly. that is, after this years 60 per cent share price rise for regeneron, fuelled by optimism aboutanother antibody drug, anti-inflammatory dupixent.

A covid-19 antibody treatment being developed by vir and the uks glaxosmithkline, which this week moved into phase 3 trials, might get a look-in too. gsk was so impressed by virs approach that it paid $250m for a 6 per cent stake in the san francisco-based company in april.

There will be limits on how much the drug companies can charge, partly for reputational reasons. that will limit profits, as these are costly drugs to make. nor is there enough production capacity to meet demand in full. that has been estimated to be at least 25m doses, half as much again as the monoclonal treatments administered annually in the us.

Still, companies are joining forces to scale up production. regeneron is teaming up with swiss rival roche; eli lilly with amgen. they expect to be able to produce millions of doses next year. priority should go to the most vulnerable groups. that would usefully bridge the gap until a vaccine arrives.

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