Covid-19 cases are on the rise around the world, fueled by highly contagious variants of the coronavirus emerging far from where they were first discovered.
The spread of these variants, scientists say, shows how small, random changes to the genetic code of the virus threaten to reverse progress in rebounding a global pandemic that killed at least three million people. As for variants, spread in the US and Canada, Europe and Latin America.
Scientists say variants can be controlled with now-known public health measures such as wearing a mask and social distancing, despite evidence that some strains can bypass the immune response triggered by vaccination or previous infection.
In the UK, for example, where a variant known as B.1.1.7 triggered a deadly new outbreak in winter, new cases have slowed to a trickle after strict lockdown and rapid vaccination.
Scientists are also hopeful that current vaccines will at least limit the number of people who become seriously ill and die from Covid-19, even if the variants weaken the vaccines’ effectiveness in preventing infection. Vaccine manufacturers are already testing new versions of their shots that are retuned for attack variants.