Does it spread more easily? Make people sicker? Mean that treatments and vaccines won't work? Questions are multiplying as fast as new variants of the coronavirus, especially the one moving through England and now popping up in the U.S. and other countries.
Scientists say there is reason for concern and more to learn but that the new variants should not cause alarm.
Q: Where did this new variant come from?
A: New variants have been seen almost since the virus was first detected in China nearly a year ago. Viruses often mutate, or develop small changes, as they reproduce and move through a population.
Most changes are trivial. A more concerning situation is when a virus mutates to help it escape from drugs or the immune system, or if it acquires a lot of changes that make it very different from previous versions.
Q: How does one variant become dominant?
A: That can happen if one variant takes hold and starts spreading in an area, or because "super spreader" events helped it become established.
It also can happen if a mutation gives a new variant an advantage, such as helping it spread more easily than other ones that are circulating.
Scientists are still working to confirm whether the variant in England spreads more easily, but they are finding some evidence that it does.
Q: What's worrisome about the British variant?
A: It has many mutations — nearly two dozen — and eight are on the spike protein that the virus uses to attach to and infect cells. The spike is what vaccines and antibody drugs target.
Dr. Ravi Gupta, a virus expert at the University of Cambridge in England, said modeling studies suggest it may be up to two times more infectious than the version that's been most common in England so far.
Q: Does it make people sicker or more likely to die?
A: "There's no indication that either of those is true, but clearly those are two issues we've got to watch," Landrigan said. As more patients get infected with the new variant, "they'll know fairly soon if the new strain makes people sicker."
A WHO outbreak expert, Maria Van Kerkhove, said that "the information that we have so far is that there isn't a change" in the kind of illness or its severity.
Q: What do the mutations mean for treatments?
A: A couple of cases in England raise concern that the mutations in some of the emerging new variants could hurt the potency of drugs that supply antibodies to block the virus from infecting cells. One drugmaker, Eli Lilly, said that tests in its lab suggest that its drug remains fully active.
Q: What about vaccines?
A: Scientists believe current vaccines will still be effective against the variant, but they are working to confirm that. On Wednesday, British officials reiterated that there is no data suggesting the new variant hurts the effectiveness of the available vaccines.
Vaccines induce broad immune system responses besides just prompting the immune system to make antibodies to the virus, so they are expected to still work, several scientists said.
Q: What can I do to reduce my risk?
A: Follow the advice to wear a mask, wash your hands often, maintain social distance and avoid crowds, public health experts say.
"The bottom line is we need to suppress transmission" of the coronavirus, said the WHO's director-general, Dr. Tedros Adhanom Ghebreyesus. "The more we allow it to spread, the more mutations will happen."