The number of people catching COVID-19 is on the rise, according to Government data. In the seven day period ending 22 July – the same week that England moved to step 4 of the Roadmap and legal restrictions related to COVID-19 were removed – there were 325,223 people testing positive for coronavirus.


On England's reopening, 19 July 2021, the Prime Minister said: "though both hospitalisations and deaths are sadly rising, these numbers are well within the margins of what our scientists predicted at the outset of the roadmap."

However, writing in The Lancet, some scientists have said that rising case numbers "will inevitably lead to increased hospital admissions, applying further pressure at a time when millions of people are waiting for medical procedures and routine care."

They also warn that reopening "provides fertile ground for the emergence of vaccine-resistant variants".

After the letter's publication, the hashtag 'Plague Island' began trending on Twitter.

How do vaccine-resistant variants develop?

"To put it simply, the SARS-CoV-2 virus changes a little every time it infects someone and replicates," explains Dr Jeremy Rossman, a virologist who was not involved in the research. "Most of these changes have no affect on the virus or how it spreads or causes disease."

These changes, or mutations, are random. Whether they increase the spread around the population, though, depends on the mutation.

"You can get any random mutation appearing, but if it doesn’t [help] that virus spread, then that variant doesn’t propagate and it’s usually not much of a concern.

Read more about COVID-19 variants:

"However, mutations that make the virus spread better from person to person, or mutations that allow the virus to spread in people that have immunity (i.e. vaccinated or previously infected people), all will be selected for and we’ll tend to see these variants more often, simply because they infect more people."

This risk is present in every country that has high levels of virus transmission, explains Rossman. But with so many of the UK population vaccinated, the pressure is on the virus to change in a way that will allow it to evade people's immunity.

"It’s possible that none of the mutations and variants that arise will affect the COVID-19 disease, transmission of the virus or the efficacy of coronavirus vaccines.

"However, the risk is clear. The more people infected, the more chances there are that the virus will change in a way that does affect COVID-19 disease, creating a new variant of concern.


"The more people infected, the greater the risk – in addition to the risks posed to the health of the still significant percentage of the population that is still unvaccinated."

About our expert, Dr Jeremy Rossman

Honorary senior lecturer in virology, and president of Research-Aid Networks at the University of Kent. His research focuses on the process of infectious disease outbreaks.


Amy ArthurEditorial Assistant, BBC Science Focus

Amy is the Editorial Assistant at BBC Science Focus. Her BA degree specialised in science publishing and she has been working as a journalist since graduating in 2018. In 2020, Amy was named Editorial Assistant of the Year by the British Society of Magazine Editors. She looks after all things books, culture and media. Her interests range from natural history and wildlife, to women in STEM and accessibility tech.