Dr Hilary Jones issued a warning over a reliance on herd immunity amid the coronavirus pandemic, on Good Morning Britain on Tuesday.
The doctor addressed new concerns about a Covid-19 vaccine, and whether one will be ready by Christmas as it has previously been hoped - while there is also uncertainty over what immunity a vaccine may offer.
Hilary urged people to follow the government guidelines, whether or not they had had the virus.
There's now uncertainty again over herd immunity and coronavirus antibodies, and whether these give someone immunity for long enough.
With antibodies now shown to disappear quite quickly in the more vulnerable groups after time, Hilary warned that group immunity could be "way, way off".
Speaking on GMB to host Sean Fletcher, Hilary discussed a recent study looking into the antibodies and how they worked in patients.
It has been reported that Covid-19 antibodies were shown to fall rapidly after recovery from the virus, in the study, meaning they don't last for as long as it was initially believed.
Immunity may only last a few months it seems, possibly dashing hopes of a herd immunity plan.
Many were relying on this plan while the wait for a vaccine continues, and while vaccine hopes are rising due to ongoing testing it's now not clear if one vaccine will be enough.
Hilary said: "Unfortunately it looks like herd immunity is way, way off."
He revealed how in older age groups and the most vulnerable, the antibodies lessened much quicker - while the vaccine trials saw a different result.
Hilary went on: "We can’t rely on individual or herd immunity," adding that people who think they had it "still need to abide by the guidelines".
Discussing this as "natural immunity" he repeated that it was the older and vulnerable groups who had less antibodies over time.
He revealed: "Being exposed [to the virus] does not confirm individual immunity going forward.
"So may people have been relying on [herd immunity]... that's blown out of the water as well, we've got to forget getting Covid-19 will make us immune, that's a real blow."
He then went on to state the vaccine trials have shown so far that it can give "a good immune response," making it more promising.
But with this, there was no certainty over how long the immunity lasted for, and whether someone who had the vaccine could be reinfected by the virus.
Good Morning Britain airs weekdays at 6am on ITV.