A new study suggests that Pfizer’s COVID-19 vaccine is effective against new forms of the coronavirus discovered in Britain and South Africa. Researchers say they collected blood from 20 people who received the vaccine, developed by Pfizer and its German partner BioNTech. Antibodies from those individuals were found to work against the coronavirus in laboratory experiments. Mutated versions, or variants, of the coronavirus first appeared in Britain and South Africa. The two variants have caused concern among world health experts because they appear to spread more easily than the first version. The mutated variant found in Britain has also appeared in the United States and other countries.