SAN FRANCISCO, Calif. (KRON) – A new study on the effectiveness of vaccines is a mixed bag — Promising news for those fully vaccinated, not so much for those who are not.  

Some good news and bad news about the COVID-19 vaccine’s effectiveness against the Delta variant. 

“If you are fully vaccinated, it’s unlikely you will get infected. You will get very ill and very unlikely you will wind up in the hospital,” Dr. John Swartzberg, UC Berkeley infectious disease specialist, said. 

But the Pasteur Institute Study reported in the Journal Nature found significantly bad news for those who have only received one dose of the 2-dose Pfizer vaccine.

“They’re hardly protected at all, almost as if they have not had any vaccination,” Dr. Swartzberg said.

Infectious disease experts say it continues to be a race against time, to increase the number of those fully vaccinated.  

“If we have lots of cases we will have lots of variants. If we have few cases, then few variants and that’s why getting every day vaccinated is so important as we want to try to control it now with the vaccines that we have now that we know work against the variants,” Dr. George Rutherford, UCSF epidemiology professor, said. 

Medical experts say with the Delta variant so much more transmissible, it’s not just about protecting yourself and others but preventing long-term illness. 

“We really need to be careful, we are learning more about this long covid syndrome, it’s very real and it can be quite debilitating,” Dr. Rutherford said.

It’s important to note this study did not look at the effectiveness of Moderna or Johnson and Johnson.