A senior public health official has suggested that children and young people should be left to catch Covid if the vaccine does not work at preventing transmission of the virus.

Head of immunisation at Public Health England, Dr Mary Ramsay, said that if the vaccine does not prevent Covid-19 transmission, the virus may need to be allowed to 'circulate among younger people'.

Dr Ramsay also suggested the virus could be treated the same as flu, where those most vulnerable were protected but those who were little affected by it could continue life as normal.

Speaking to the Commons Science and Technology Committee about whether it was likely the entire population would need to be vaccinated, Dr Ramsay said: “We may need to accept, if the vaccine doesn’t prevent transmission, that we’re going to protect the people who are really vulnerable and who are going to die and have serious disease, but we allow the disease to circulate in younger people where it’s not causing much harm.

“That may be the situation we go to, like we are with things like flu, that we accept that a lot of people get flu but we protect those who are most vulnerable.

“That may be the outcome, I’m hoping it will be a bit better than that.”

It comes as a new study found that while previous Covid-19 infection provides some immunity (for at least five months), people may still carry and transmit the virus.

Experts have warned that a small number of those with immunity may still be able carry the virus in their nose and throat and therefore have a risk of transmitting it to others.

The first report from Public Health England’s (PHE) Siren study found that antibodies from past infection provide 83 per cent protection against reinfection for at least five months.

This suggests that people who contracted the disease in the first wave may now be vulnerable to catching it again.

Although reinfections in people with antibodies were rare, the researchers identified 44 potential reinfections among 6,614 participants who showed evidence of previous infection.

Senior medical adviser at PHE and the Siren study lead, Professor Susan Hopkins, said: “This study has given us the clearest picture to date of the nature of antibody protection against Covid-19 but it is critical people do not misunderstand these early findings.

“We now know that most of those who have had the virus, and developed antibodies, are protected from reinfection, but this is not total and we do not yet know how long protection lasts.

“Crucially, we believe people may still be able to pass the virus on.

“This means, even if you believe you already had the disease and are protected, you can be reassured it is highly unlikely you will develop severe infections, but there is still a risk that you could acquire an infection and transmit to others.

“Now, more than ever, it is vital we all stay at home to protect our health service and save lives.”

Since June, PHE has been regularly testing tens of thousands of healthcare workers across the UK for new Covid-19 infections as well as the presence of antibodies, which suggest people have been infected before.

The study leaders are clear that this first report provides no evidence towards the antibody or other immune responses from coronavirus vaccines, nor should any conclusions to be drawn on their effectiveness.

The study, which has not been peer-reviewed, will consider vaccine responses later this year.

Scientists concluded that naturally-acquired immunity as a result of past infections provides 83 per cent protection against reinfection, compared with people who have not had the disease before.

They added that this appears to last at least for five months from first becoming sick.

While the research will continue to assess whether protection may last for longer, this means people who contracted the disease in the first wave may be able to get it again.