Why should I vaccinate to protect other people?
Here is what the checked sources say. Each title links to the original.
Coronavirus disease (COVID-19): Herd immunity, lockdowns and COVID-19
WHO explains herd immunity, also called population immunity, as indirect protection from an infectious disease when a population is immune through vaccination or past infection. WHO says the share needed varies with each disease: about 95% vaccinated for measles and about 80% for polio. In 2020 it said the share needed for COVID-19 was not known. One aim is to protect vulnerable people who cannot be vaccinated, for example because of allergic reactions to the vaccine. WHO notes the page stopped being updated on 31 December 2020.
The Japanese experience with vaccinating schoolchildren against influenza
This study compared national death statistics for Japan and the US from 1949 to 1998; it was not a trial. From 1962 to 1987 Japan vaccinated most schoolchildren against flu. During those years Japan's excess pneumonia and influenza deaths, mostly among older people, fell from three to four times the US level to about the US level, and rose again as the program ended. From these trends the authors estimated the program prevented about 37,000 to 49,000 deaths a year, about one death per 420 children vaccinated.
Decline in invasive pneumococcal disease after the introduction of protein-polysaccharide conjugate vaccine
After a pneumococcal conjugate vaccine for young children was licensed in the US in 2000, this CDC surveillance study of 16 million people compared rates of serious pneumococcal infection in 2001 with 1998 to 1999. In children under two, rates fell 69%, from 188 to 59 cases per 100,000. Adults, who were not getting this vaccine, also had lower rates: from 11.2 to 7.6 per 100,000 at ages 20 to 39 (32%) and from 60.1 to 49.5 at 65 and older (18%). The authors said the vaccine "may be reducing" adult disease.