The Pfizer–BioNTech and Oxford–AstraZeneca COVID-19 vaccines are effective against the highly infectious Delta variant of SARS-CoV-2 — but their protection drops away over time, a study of infections in the United Kingdom has concluded.

Whaat happens if you mix AstraZeneca and Pfizer COVID-19 vaccines?

Researchers studied mixing and matching Pfizer's vaccine with AstraZeneca's, which is made using similar technology as J&J's. There, too, researchers found that people who got an AstraZeneca shot followed by Pfizer four weeks later produced more antibodies than those who received two AstraZeneca shots.

Do the current COVID-19 vaccines protect against the new variant?

• FDA-authorized COVID-19 vaccines help protect against Delta and other known variants.
• These vaccines are effective at keeping people from getting COVID-19, getting very sick, and dying.