Overseas research teams said that antibodies produced via infection or vaccination may not work well against new variants of the novel coronavirus from South Africa and Brazil.
However, antibody production is not the only way in which vaccines are known to enhance immunity, and researchers said vaccines for the original type of novel coronavirus are considered effective against the variants to a certain extent.
Changes in variants of the novel coronavirus are concentrated in the section of the virus that is crucial for infection, and South African and Brazilian variants have more such mutations than other variants.
Rockefeller University and other institutions tested the vaccine made by U.S. pharmaceutical company Pfizer Inc. and U.S. biotechnology firm Moderna, Inc. against South African and Brazilian variants.
They collected blood samples from 20 people who had taken the vaccines, and found the infection-preventing effectiveness of their antibodies to be only one-third as strong as it is against the original form of the novel coronavirus. Effectiveness was halved against the British variant.
Meanwhile, researchers in South Africa and elsewhere analyzed blood samples collected from 44 people who had recovered from coronavirus infections. In half of those cases, they found that the antibodies had little effect on the South African variant of the virus.
Tohoku University Prof. Koetsu Ogasawara, an immunology expert, said: "The effects of antibodies against variants are less effective, compared to against original form, but vaccines have immune-enhancing effects other than producing antibodies. Vaccines may be effective to some extent to prevent infection with the variants.
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