Ten people have been given antibodies as a form of emergency protection after being exposed to coronavirus, in the first trial of its kind.
The experimental jab is being offered to people who have been in close contact with a confirmed Covid-19 case within the past eight days.
If it proves effective, it could protect vulnerable people who have not yet been, or cannot be, vaccinated.
And it could help to contain outbreaks.
The trial, run at University College London Hospitals (UCLH) NHS Trust, is looking at whether an injection of two different antibodies could prevent someone who has been exposed to Covid from developing the disease – or at least from becoming very ill.
Vaccines take weeks to offer full protection, meaning it’s too late for them to be given once someone already has the virus brewing in their system.
But this monoclonal antibody treatment, developed by the drugs company AstraZeneca, should work to neutralise the virus immediately.
And it gives ongoing protection for up to a year.
It could mean healthcare workers, hospital patients and care home residents could be given the treatment if they have been exposed to a known Covid case.
It could be offered to people with health vulnerabilities by their GPs.
And it could be used to prevent one or two cases turning into an outbreak in settings like student accommodation.