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Project #60:
Describing the rates of COVID-19 vaccine breakthrough in fully vaccinated individuals in England


The vaccination programme for COVID-19 in the UK started on 8th December 2020. As with any vaccine, despite being vaccinated, COVID-19 vaccine breakthrough is likely and a small number of people will still fall ill, be hospitalised, or die from COVID-19.

As of 30th June 2021, a total of 10,782,870 individuals were identified as being fully vaccinated against COVID-19, with a median follow-up time of 43 days (IQR: 23-64). From within this population, the total number of COVID-19 vaccine breakthrough cases was 17,030 (0.2%). The majority of COVID-19 vaccine breakthrough cases were mild with relatively few fully vaccinated individuals being hospitalised or dying as a result. However, some concerning differences in rates of breakthrough cases were identified in several clinical groups; comorbidities with the highest rates of breakthrough COVID-19 included renal replacement therapy, organ transplant, haematological malignancy, and immunocompromised

The continued increase in numbers of positive SARS-CoV-2 tests in England are concerning and, as numbers of fully vaccinated individuals increases and follow-up time lengthens, so too will the number of COVID-19 breakthrough cases.

To help inform roll-out of the third and booster dose vaccination, and to support the redesignation of dialysis patients into the 3rd dose group, with eligibility for subsequent vaccination, this analysis was rerun in November 2021 (with the previous CKD group split out into categories). As expected, there had been a rise in all rates (calculated per 1000 person-years);

  • Positive SARS-CoV-2 test from 12.33 (12.14-12.51) to 99.44 (99.31-99.57)
  • COVID related hospitalisation from 0.70 (0.65-0.74) to 2.31 (2.29-2.34)
  • COVID related death from 0.12 (0.1-0.14) to 0.64 (0.63-0.66)

Despite these increases, reassuringly, breakthrough cases remain relatively mild; 312, 530 Positive SARS-CoV-2 tests vs 3840 COVID-19 related deaths (with the majority (80%) of deaths occurring in those over 70 years of age).


  • Study leads: Millie Green
  • Organisation: University of Oxford and London School of Hygiene and Tropical Medicine