Additionally many vaccines don't induce sterilising immunity, yet we continue to use them.
The advantages are
n the absence of sterilising immunity, what effect might SARS-CoV-2 vaccines have on the spread of a virus through a population? If asymptomatic infections are possible after vaccination, there has been concern that SARS-CoV-2 will simply continue to infect as many people as before. Is this possible?
Asymptomatically infected people typically produce virus at lower levels. Though there is not a perfect relationship, usually more virus equals more disease. Therefore, vaccinated people are less likely to transmit enough virus to cause severe disease. This in turn means that the people getting infected in this situation are going to transmit less virus to the next susceptible person. This has been neatly shown experimentally using a vaccine targeting a different virus in chickens; when only part of a flock was vaccinated, unvaccinated birds still showed milder disease and produced less virus.
So, while sterilising immunity is often the ultimate goal of vaccine design, it is rarely achieved. Fortunately, this hasn’t stopped many different vaccines substantially reducing the number of cases of virus infections in the past. By reducing disease levels in individuals, this also reduces virus spread through populations, and this will hopefully bring the current pandemic under control.
https://theconversation.com/coronavirus-few-vaccines-prevent-infection-heres-why...