After spending 18 months learning from a distance, Stanford is planning to bring all undergraduates back to campus in the fall for the first time since March 2020. But, uncertainty still lingers. In light of the rise of the highly contagious Delta variant and as breakthrough cases become more common, here’s what those returning to campus need to know about variants and vaccinations. 

For the vaccinated

The most prominent COVID-19 variant in California is the Delta variant. Compared to the original strain, clinical fellow in the Stanford School of Medicine in infectious disease and geographic medicine Karen Jacobson, M.D. ’08, said the Delta variant is significantly more transmissible. “Each person who is infected [with the original strain of SARS-CoV-2 will] infect approximately two or three other individuals,” Jacobson said. “With Delta that number is more like eight.” 

Stanford Medicine epidemiology and population health professor Julie Parsonnet explained via email that Delta is more likely to cause mild or asymptomatic infection in vaccinated people. She added she thinks it is “more likely to be transmitted from vaccinated people to others.”

Those who are vaccinated can still become infected with COVID-19 and can pass it on to those around them. Symptoms may be minimal, but the virus will still be very dangerous for those who are unvaccinated, immunocompromised or within close contact with an immunocompromised person. 

Breakthrough cases are also becoming more common. Since early July, the breakthrough case rate per 100,000 Santa Clara County residents has increased from 1 to 9.7 people and continues to rise. This number is still significantly less compared to the unvaccinated case rate of 32.3 people per 100,000 residents.

For the unvaccinated

For those who are unvaccinated, the future will be more difficult. “Anyone unvaccinated has to assume they will get infected, that they are also likely to get sick and possibly infect others,” Parsonnet wrote. 

In Santa Clara County, unvaccinated people are being infected and hospitalized at alarmingly higher rates compared to those who do have the vaccine. Unvaccinated people also make up the vast majority of COVID-19 hospitalizations, and according to Jacobson, are 95% of the total. This includes young and previously healthy people, she said. 

Almost everyone on Stanford’s campus should be vaccinated after the University announced vaccines would be mandated for the coming year. Students will only be able to request exceptions to the requirement for medical or religious reasons. 

Jacobson explained that those who are unvaccinated have to carry the burden of not knowing how their bodies will respond to infection. Symptoms could be mild, or they could be deadly. 

Since a vaccination status option was added to the campuswide Health Check forms in May, approximately 95% of all users who regularly submit responses are vaccinated. 

Masking and testing 

Looking to the fall, Stanford plans to adhere to CDC guidance and will require masks in all public indoor spaces, regardless of vaccination status. 

“We need masking both to keep other vaccinated people as well as unvaccinated people safe,” Jacobson said. “Be flexible and do what you can to be part of the solution.”

Stanford will also require unvaccinated and vaccinated students to get tested both weekly and on arrival, as well as complete a daily Health Check. 

“You have to have very good comprehensive testing services available for people who are symptomatic, but also regular screening for anyone who’s not vaccinated, who is at risk, or has not responded to the vaccine,” Jacobson said. 

In addition to regular testing, public health officials and the CDC are encouraging anyone to get tested if they have symptoms to prevent further infection as social distancing rules begin to relax nationwide.

As those who are vaccinated and unvaccinated have a similar risk of transmissibility, the importance of testing and self-awareness is growing.

“Don’t assume mild symptoms are allergies or just a cold,” wrote Stanford professor of medicine and infectious diseases Marisa Holubar M.S. ’14.