“Our belief [that the vaccines work against Omicron] is rooted in science: If a virus achieves immune escape, it achieves it against antibodies, but there is the second level of immune response that protects from severe disease—the T-cells,” he said.

“Even as an escape variant, the virus will hardly be able to completely evade the T-cells.”…

Stanley Plotkin, a veteran scientist who developed a number of vaccines, including the shot against rubella, said Dr. Sahin’s assumptions were “gratuitous and without any proof.”

Dr. Plotkin said that data so far indicated that antibodies played a key role in protecting from coronavirus, and that there was little evidence that T-cells would be fully protective against severe symptoms.

“Antibodies are clearly the major correlate of protection and we have little evidence that in the absence of antibodies the T-cells will do the job,” Dr. Plotkin said. However, he said it would make evolutionary sense for mutations in the virus that make it more infectious but less deadly to human hosts to become dominant over time.