AMSTERDAM—Dutch health authorities on Thursday said most of the 62 people who tested positive for COVID-19 after arriving on two flights from South Africa last week had been vaccinated, lending weight to a call for pre-flight testing regardless of vaccination status. In addition, all 14 passengers who were later found to have been infected with the Omicron variant were vaccinated, health officials said on Thursday. Under rules in place at the time, more than 600 passengers were able to board the KLM airline flights from Johannesburg and Cape Town on Nov. 26 with either proof of vaccination or recent negative COVID-19 test results. A spokesman for the health authority for Kennemerland, in which Schiphol airport is situated, said “around 90 percent” of those that tested positive were vaccinated. A spokesperson for the Netherlands’ Institute for Health (RIVM) confirmed on Thursday that this included all of the passengers with Omicron. KLM …