The university confirmed that at least seven cases were all symptomatic and come amid a surge in infections in the area in a letter to students last week.
"As you have seen in the national news, cases of Covid-19 have been ticking upward," Stanford University officials said.
They added: "We are seeing some of this in our own community, where we are experiencing an increase in the number of student Covid cases, including among fully vaccinated individuals."
Although coronavirus vaccines can greatly reduce an individual’s chance of infection or serious illness, they are not 100 per cent effective.
“Vaccination continues to provide effective prevention against serious illness from Covid-19, but some ‘breakthrough’ cases are occurring here and around the country, driven in large part by Covid-19 variants,” the university said.
While the US has seen a large decrease in coronavirus cases across the nation in recent weeks, the more transmissible Delta variant is causing a localised surge in infections.
In the Golden State, health officials have pleaded with people to get vaccinated for Covid-19 as community outbreaks have emerged and overall infections creep up.
Stanford University officials have reassured students that "vaccination continues to be our best defense against severe Covid-19 infection."
They noted that “face coverings, physical distancing and hand hygiene remain powerful ways to prevent the transmission of Covid-19.”
The university said: “Even if you test negative for Covid-19, we recommend wearing a face covering if you have cold symptoms to keep others healthy.”
California’s Los Angeles County, the most populous county in the country, has recently reinstated its mask mandate, even for those with two vaccinations as it struggles to prevent a wave of infections.
Statewide, over 60 per cent of residents or over 21 million people have received two doses of a coronavirus vaccination.
They urged students to get tested for the virus if experiencing Covid-19 symptoms even if they think they are due to a “common cold or allergies”.
The state Department of Public Health has said that 99 per cent of cases between 1 January and last week were among those who haven’t been vaccinated.
Additional reporting by the Associated Press