Yes, vaccination of 50% of the people results in a four-fold decrease in transmission - more or less. Transmission varies with the virus. Measles is so infectiv

Yes, vaccination of 50% of the people results in a four-fold decrease in transmission - more or less. Transmission varies with the virus. Measles is so infective that one person can infect all the susceptible people in a 25 foot square room in 1 minute. SARS-2 is a lot less infectious. Specialists in viral spread can show different maps for each virus - usually over a range of infectivity ratios (R value). Sars-2 = https://www.thelancet.com/journals/laninf/article/PIIS1473-3099(20)30840-9/fulltext https://www.thelancet.com/journals/laninf/article/PIIS1473-3... Measles has a value of 12-18...