Almost half of UK COVID cases in people given 1 dose of vaccine, mild cases

• Almost half of coronavirus cases in the UK have been in people who have been vaccinated, according to a large UK study.
• The virus appears to be “lacking” in people who have no immunity, the study manager said.
• Hospitalization in the UK could level off and possibly decline in the UK, he told Insider.
• See more stories on the Insider business page.

Almost half of COVID-19 cases in the UK are in people who are partially or fully vaccinated, according to data from a large study.

The discovery came from the ZOE COVID study conducted by King’s College London. It uses information recorded daily by more than a million people to predict COVID-19 trends

As of July 15, an estimated 17,581 daily new cases of COVID-19 in the UK were in unvaccinated people, the study’s authors said in a press release on Thursday.

This compares to about 15,537 new cases of COVID-19 in people who have received at least one dose of the vaccine, which is about 47% of all cases.

“This is probably because the virus is lacking in people to infect who have not already been exposed and who do not have a natural immune unit in these groups. [unvaccinated people]”said Professor Tim Spector, epidemiologist at King’s College London, in a video accompanying the press release.

Spector is the lead author of the ZOE COVID study.

People who have only received a single dose of the vaccine are less protected against mild symptoms of COVID

COVID-19 is spreading faster in those who have only received a single dose of the vaccine, as shown in the graph below from ZOE data:

Zoe COVID Symptoms Study / Insider

In an email to Insider, Spector said: “Our research showed fewer and milder symptoms were reported in people who were vaccinated compared to unvaccinated adults who had contracted the virus.”

This matches other data suggesting that two doses provide the best protection against the Delta variant, and one dose gives much less, but better than none.

According to figures from Public Health England (PHE), one dose of AstraZeneca or Pfizer vaccine reduced the risk of catching mild symptoms of COVID-19 by 35%.

However, even a single dose of the vaccine protects against the more serious risk of COVID-19, reducing the risk of hospitalization by 80%.

Two doses of the vaccine were much more protective, reducing the risk of having mild symptoms of the disease by about 80% and the risk of hospitalization by 96%, according to data from PHE.

Preliminary data from ZOE also suggests that the risk of long-term COVID is also significantly reduced by two doses of the vaccine, Spector told Insider.

Cases seem to be leveling off among the unvaccinated – a good signal

Cases in unvaccinated people were estimated to be 22% lower than the previous week, while cases in vaccinated people increased by 40%. This suggests that the wave of the unvaccinated population has now peaked in the UK, the study’s authors said in the press release.

Hospitalization rates in the UK have increased slightly, with 3,615 new COVID patients in hospital as of July 14, up from around 900 in May.

Cases continue to increase thanks to the Delta variant. “I think as more people in the UK get their second vaccine, hospitalizations will level off and likely drop,” Spector told Insider in an email.

Spector told Insider the numbers need to be taken with caution, as there are fewer contributors to the ZOE app who are now unvaccinated.

“We will be monitoring cases closely over the next few days to confirm the peak.”