Are there multiple strains of Covid-19?
Scientists in China believe they have identified two unique strains of the new coronavirus—a discovery that, if confirmed, could mean new variants will crop up year after year in the same way as seasonal flu. Researchers from Peking University examined the genetic sequences of viral samples from 103 Chinese Covid-19 patients. They say they found two forms of the virus: “L-type” and “S-type.” The L-type was more prevalent among those who had the disease early in the outbreak; the S-type was more common in later samples. Counterintuitively, it appeared that the former was derived from the latter. Researchers think the S-type didn’t make as big an impact initially because it isn’t as virulent. The differences between the two are tiny; they both carry the same symptoms and are equally deadly. But if there are indeed two strains, it’s safe to assume that more will emerge in the months and years ahead. That’s how seasonal flu works: New variants crop up as viruses mutate to overcome people’s immune systems. Some scientists have questioned the finding, noting that the study is based on a small sample and that such mutations don’t make the virus behave differently. But others say the research shows that the coronavirus will be with us for years to come. Ian Jones, from Reading University in the U.K., tells New Scientist: “I don’t see it going away any time soon.” ■