Good evidence from real-world data that Covid-19 vaccines are working – experts

Nilima Marshall, PA Science Reporter
·4-min read

There is good evidence from early real-world data in the UK that Covid-19 vaccines are working after the first dose, experts have said.

However, in a document released on Friday by the Scientific Advisory Group for Emergencies (Sage), which advises the Government, they have cautioned that coronavirus jabs may fail to prevent hospital admissions amongst a very small number of people, particularly those who are frail and elderly.

The findings are based on data from more than 52,000 patients who were admitted to hospital between December 8 – when the UK began its mass vaccination rollout – and April 10.

Calum Semple, professor in child health and outbreak medicine at the University of Liverpool, who co-led the study, said that their analysis was designed to give Sage “a very early signal on whether vaccines were working in the real world”.

He said: “The absolute numbers of people being admitted to hospital after 21 days of the first dose is tiny.

“It is very small, but it does occur – it is mostly occurring in the group most at risk of severe disease, which is the elderly people (and) people (who) are very frail and very old.

“This is good real world evidence of it working, but there are some few failures.

“And when these failures do occur, sadly, people die, but that is because they are elderly and frail.”

As part of their study, the experts looked at 52,280 hospital admissions, of which 3,598 had data showing they had received the first dose of a Covid-19 vaccine.

For most of these patients, the time between vaccination and hospital admission was up to 15 days, where infection occurred before immunity had developed.

Three weeks is the point at which experts believe maximum immunity from a single dose becomes apparent.

The researchers said that there is a possibility that vaccinated elderly and vulnerable people may have been been exposed to coronavirus after wrongly assuming they were immune.

Prof Semple, who is also a member of Sage, said: “Many people are acquiring Covid within two weeks of being vaccinated, which does indicate that people are letting their guard down.

“There is there is evidence here that people are, unfortunately, assuming that they are protected very quickly after vaccination and that is not the case.”

Of those vaccinated, 526 people with a positive Covid-19 test were admitted to hospital more than 21 days after receiving their first dose, and 113 died.

The experts said these cases represent vaccine failure, which occurs when a person contracts a disease in spite of being vaccinated against it.

Dr Annemarie Docherty, an honorary consultant in critical care at the University of Edinburgh, and study co-author, said: “Our take home messages are that this is some real world data, which does show some vaccine failure, but this is not unexpected, and reflects what the (clinical) trials have shown.”

However, she added that their data may be under-representing vaccine failure as the risk of Covid-19 exposure has reduced since early January when infections were at its peak.

Dr Docherty said: “The one caveat is that (while) lots of people have been vaccinated recently, their risk of exposure to Covid is much lower than it was in January and February.

“So whilst we think this is good news, potentially, we are under representing vaccine failure, because people aren’t exposed to the virus.”

She said their study only recruited patients who were admitted to hospital and may not reflect vaccine effectiveness within the wider community.

Commenting on the paper, Deborah Dunn-Walters, chairwoman of the British Society for Immunology Covid-19 taskforce and professor of immunology at the University of Surrey, said: “The primary aim of all vaccination campaigns is to stop people getting seriously ill and save lives.

“However, no vaccine is 100% effective in stopping disease and so it’s important that we monitor vaccine rollout and examine any cases where an individual is hospitalised for Covid-19 following vaccination.

“This will help us refine and improve vaccination regimes in future.”

She added: “Overall, we can be confident that the Covid-19 vaccination programme is highly effective in preventing serious disease and saving lives.

“I urge anyone who is offered a Covid vaccine to get it.”