COVID-19 vaccine effectiveness against hospitalisation and death of people in clinical risk groups during the Delta variant period: English primary care network cohort study

Heather Whitaker, Ruby S. M. Tsang, Rachel Byford, Carole Aspden, Elizabeth Button, Praveen Sebastian Pillai, Gavin Jamie, Debasish Kar, John Williams, Mary Sinnathamby, Gemma Marsden, William H. Elson, Meredith Leston, Sneha Anand, Cecilia Okusi, Xuejuan Fan, Ezra Linley, Cathy Rowe, Silvia D’Arcangelo, Ashley Otter, Joanna Ellis, Richard Hobbs, Victoria Tzortziou Brown, Maria Zambon, Mary Ramsay, Kevin Brown, Gayatri Amirthalingam, Nick Andrews, Simon de Lusignan, Jamie Lopez Bernal