That sunny picture was clouded — but not eclipsed — by a worrisome finding: If you looked only at the 17 most powerful antibodies produced in response to the two vaccines, in 14 cases the neutralizing effect was “reduced or abolished” by the presence of a mutation called E484K, one of the hallmarks of the South Africa strain.

That may sound alarming, but it actually bespeaks the power of the immune system’s response to these particular vaccines. If the antibodies and other immune proteins generated by vaccination were a team, its bench would be so deep that 14 of its 17 top players could be injured or sent to the locker room and it would still prevail over South Africa’s viral variant.

Even if viruses elude some antibodies, the adaptive immune system lives up to its name. After learning to recognize the original Wuhan virus, either via a vaccine or from previous infection, an encounter with the South Africa strain prompts the body’s white blood cells to churn out antibodies that get better at targeting the altered virus.

“It adapts,” Luchsinger said.