How effective is the Covid-19 vaccine in at-risk groups?

Posted on: 14th July 2021

New data from Public Health England (PHE) suggests that the COVID-19 vaccines used in the UK are as effective at preventing symptomatic disease in the majority of people with underlying health conditions compared to the rest of the population.

The study, which included more than 1 million people in at-risk groups, found:

  • overall vaccine effectiveness against symptomatic disease in risk groups is approximately 60% after one dose of either AstraZeneca or Pfizer-BioNTech, with little variation by age
  • after two doses, vaccine effectiveness is 81% with AstraZeneca in people in risk groups aged 16 to 64. No data is available for Pfizer-BioNTech
  • in people in risk groups aged 65 and over, vaccine effectiveness with Pfizer-BioNTech is 89% and 80% with AstraZeneca.
  • for those who are immunosuppressed, vaccine effectiveness after a second dose is 74%, with similar protection to those who are not in a risk group. This rises from 4% after a first dose.

Professor Stephen Ryder, Consultant Hepatologist, said: “This is a reassuring study that confirms what we have been saying to patients since the COVID-19 vaccine programme began. We continue to recommend that everyone living with liver disease has both doses of the COVID-19 vaccine.

“Right now, the surge in COVID-19 cases in the UK is no doubt concerning for all, especially if you are considered clinically extremely vulnerable. However, the majority of hospital admissions that we are seeing have not been fully vaccinated which highlights the effectiveness of the vaccine in reducing your risk.”

Risk factors

Although age is the greatest risk factor for adverse outcomes following COVID-19 infection, certain health conditions also increase the risk of severe disease, including chronic liver disease and therapies that weaken the immune system.

People with these conditions who are at highest risk were initially advised to shield during the peak of the pandemic and all risk groups were then prioritised for vaccination. The Government announced the dose interval would be brought forward from 12 to 8 weeks for the clinically vulnerable on 14 May, and everyone in these groups should now have been offered a second dose.

Data on vaccine effectiveness among people in clinical risk groups was previously limited. Though more data is needed, protection against hospitalisation and death in risk groups is expected to be greater than protection against symptomatic disease, as has been seen in studies of the general population.

The Joint Committee on Vaccination and Immunisation (JCVI) advised that those living with immunosuppressed adults should be prioritised for vaccination to help limit the spread of the virus to people in this group.

If the planned booster programme goes ahead, the JCVI has recommended that immunosuppressed adults and their household contacts should also be among the first to be offered a third dose of vaccine in September.