Thread by @DrEricDing

BREAKING—South Africa 🇿🇦 halted use of the AstraZeneca-Oxford #COVID19 vaccine on Sunday after evidence emerged that it did not protect participants from mild or moderate illness caused by the #B1351 variant that was first seen there. 🧵
nytimes.com/live/2021/02/0…

2) Scientists in 🇿🇦 said on Sunday that a similar problem held among people who had been infected by earlier versions of #SARSCoV2: the immunity they acquired naturally did not appear to protect them from mild or moderate cases when reinfected by the variant, known as B.1.351.

3) Here was that finding in South Africa 🇿🇦 that the #B1351 variant is so evasive, people who survived #COVID19 and had immunity from it were NOT protected from reinfection— moreover, not even a little protected from severe disease either.

https://twitter.com/drericding/status/1358065355785134083

4) “It was not clear from the studies outlined by South African scientists on Sunday whether the AstraZeneca-Oxford vaccine protected against severe disease from the B.1.351 variant.

5) participants who were evaluated were relatively young and unlikely to become severely ill, making it impossible for the scientists to determine if the variant interfered with AstraZeneca-Oxford vaccine’s ability to protect against severe Covid-19, hospitalizations, or deaths.

6) “However, based on the immune responses detected in blood samples from people who were given the vaccine, the scientists said they believed that the vaccine could yet protect against more severe cases.

7) “If further studies show that it does, South African health officials said they would consider resuming use of AZ vaccine.
Even so, the fact it showed minimal efficacy in preventing mild & moderate cases adds mounting evidence that B.1.351 makes current vaccines less effective

8) Pfizer and Moderna have both said that preliminary laboratory studies indicate that their vaccines, while still protective, are less effective against B.1.351.

https://twitter.com/drericding/status/1353706396282474499

9) Novavax and Johnson & Johnson have also sequenced test samples from their clinical trial participants in South Africa, where B.1.351 caused the vast majority of cases — and both reported lower efficacy there than in the United States.

10) After the Az stoppage, South Africa 🇿🇦 now plans to use the Johnson & Johnson and Pfizer/BioNTech vaccines instead. The AZ vaccine’s efficacy had dropped to a non significant 22% with the new B1351 variant. reuters.com/article/amp/id…