Border cannot stop Covid-19, warns expert "We know that borders cannot stop infectious diseases no matter how rigid your controls are, there will always be some that comes through" 09 February, 2021 07:55 Borders "cannot stop infectious diseases", leading epidemiologist Professor David Heymann has said. Appearing on BBC Radio 4's Today Programme, he said: "We know that borders cannot stop infectious diseases no matter how rigid your controls are, there will always be some that comes through." He said most nations believe the best strategy is to deal with infections in-country, and to ensure there is a flow of travel and trade. Asked if he believed closing borders would have an immediate impact, Prof Heymann said: "We've seen that countries that have closed their borders, such as New Zealand, have kept the virus out, but now their problem is what do they when they begin to open their borders?