Fresh fears have arisen that the pandemic could be prolonged after new strains of Sars-CoV-2, the coronavirus that causes Covid-19, were detected last month. The good news is that there is no evidence that the new strains, thought to have originated in England and South Africa, are deadlier or more resistant to vaccines. What is evident is that the new strains are more transmissible. One study has shown that the new variant increases the reproduction, or R, ratio - the average number of people an infected person infects - by between 0.4 and 0.7. An added source of worry is that it has been spreading more quickly among all age groups, including young adults and secondary school-age children. The concerns are understandable, and heightened vigilance and containment efforts will be needed in what has been a year-long battle that has overwhelmed hospitals, officials and the man in the street.

But the best defence against new strains remains the same: control transmission through testing, tracing, isolating, wearing masks and observing safe distancing. Vaccines developed thus far have been aimed at the original strain of the coronavirus but are thought to generate a wide immune response that can also offer protection against mutations. Infection rates, therefore, ought to recede as vaccination drives make headway in Asia, the United States and Europe, and new lockdowns and travel restrictions rein in the winter surge in the Northern Hemisphere.