The first single-dose Covid-19 vaccine has been authorized for use in the United States after advisers to the Centers for Disease Control and Prevention unanimously voted to recommend the Johnson & Johnson shot for Americans 18 and older.
Distribution of the vaccine began Sunday night, right after CDC Director Dr. Rochelle Walensky officially rubber-stamped the authorization.
The Johnson & Johnson vaccine is a bit different than the two already in use in the US. Most importantly, it only requires one dose and is easier to handle, because it can be kept at simple refrigerator temperatures for up to three months. That makes its rollout a lot easier compared to the Moderna and Pfizer vaccines.
The technology is different too. The Moderna and Pfizer vaccines use a brand-new technology called messenger RNA, or mRNA. They deliver genetic material directly into cells, which then follow the genetic instructions to make tiny pieces that look like a part of the coronavirus.
Those little proteins stimulate an immune response, generating antibodies and immune cells that “remember” what they look like and that will be ready to respond quickly in case of a fresh attack.
The Johnson & Johnson vaccine uses viral vector technology. A common cold virus called adenovirus 26 is genetically engineered so it can infect cells, but won’t replicate there. It cannot spread in the body, and won’t give people a cold. Like the Pfizer and Moderna vaccines, it delivers genetic instructions.
The Johnson & Johnson vaccine has shown efficacy of 72% in the US and offered 86% protection against severe forms of the disease in the country. Moderna’s and Pfizer efficacy rate in clinical trials was 94% to 95%.
A version of this story appeared in the March 1 edition of CNN’s Coronavirus: Fact vs. Fiction newsletter. Sign up here to receive the need-to-know headlines every weekday.