The first link estimates numbers needed to vaccinate to avoid hospitalization for Covid in various age groups in Britain. The NYT article mentions beliefs of some seniors who aren't vaccinated and has a short discussion of altruism. 

Appendix 1: estimation of number needed to vaccinate to prevent a COVID-19 hospitalisation for primary vaccination, booster vaccination (3rd dose), autumn 2022 and spring 2023 booster for those newly in a risk group - GOV.UK (www.gov.uk)

https://www.nytimes.com/2023/02/11/health/covid-pandemic-seniors.html?unlocked_article_code=s10rHgGMxRonbF1lkjY0paRMlxDnivky99X2G8HScpKvYBSYvh9kRIBPrY1hkkjQfplSITPUzI0AcLVNNPjqrvaJl5dj0U-niK0cPsqZiLRfTLl3Exxr54Kt3Wtmuq00nXuH5QMZp7MEccC1kvwHPVRYPGn09JJeAyhv0oQ-qXjroB-CM9-ORqCvn_-HATxnahiLudVQ52fqzWrZOUZqJzKpfboQs-a9gKG1T_8fuVK1Dwjvj7OSzKHiCcHDljK8xEMEmjmsz_8PHKHGdkB_TtrT7r_PybDbvssCxc7FKoZv1bzZTNf-EO9nlP5ZjoihfCSAeAotvIBbqnE7jlM1&smid=share-url

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