There is a vaccine in a container.
Pfizer and BioNTech are investigating a new variant of the virus that causes Covid-19.
The companies said they understand the concern of experts and have begun investigations.
More data from lab tests is expected in two weeks.
The companies said that the data will provide more information about whether B. 1.1.529 could be an escape variant that would require an adjustment of the vaccine.
If an escape variant is identified, Pfizer and BioNTech will be able to adapt their vaccine within six weeks and start shipping batches within 100 days.
Johnson & Johnson said they were testing their vaccine against the new variant.
J&J said that they are testing the effectiveness of their vaccine against the new and rapidly spreading variant of the COVID-19 virus.
The variant in South Africa has about 50 different variations and more than 30 of them are on the spikeProtein that allows the virus to bind to human cells. The spread of the new variant is still in its early stages, and it is not yet clear how severe an infection would be to a person who is notvaccinated.
Several European and Asian nations have stopped flights from southern Africa. The European Commission told all 27 member states to stop travel from southern Africa after the United Kingdom suspended flights on Thursday.
The US is working with South African scientists to get the correct makeup of the variant so lab tests can be conducted. The tests would help determine if the variant can evade the vaccine's protection.
Fauci said that the data would help determine if the U.S. should impose similar travel restrictions.
Pfizer-BioNTech's two-dose vaccine is still highly effective at preventing hospitalization and death, despite its weakened strength over time. The vaccine's efficacy declined from February to October according to a study published in the journal Science.
Pfizer-BioNTech's vaccine for adults was authorized by the U.S. Centers for Disease Control and Prevention last Friday. In a clinical trial of 10,000 participants ages 16 and older, the booster dose was 98% effective in preventing infections in people who had no evidence of previous infections.