JOHANNESBURG—Dozens of nations restricted journey to and from South Africa and neighboring nations, hoping to incorporate a quick-spreading new variant of the coronavirus that researchers say may perhaps be far more contagious and could render the present crop of Covid-19 vaccines a lot less successful.

Belgian authorities explained Friday that one circumstance of the new variant had been recorded in the nation. The human being had traveled from abroad, was unvaccinated and hadn’t been contaminated with Covid-19 formerly, Health and fitness Minister Frank Vandenbroucke explained.