COVID-19, a laboratory modelling study has found.The researchers, including those from U.S. Centers for Disease Control and Prevention (CDC), noted that aircraft can hold large number of people in close proximity for long periods, which are conditions that can increase the risk for transmitting infectious diseases.Based on laboratory modelling of exposure to SARS-CoV-2 on single-aisle and twin-aisle aircraft, exposures in scenarios in which the middle seat was vacant were reduced by 23 per cent to 57 per cent, compared with full aircraft occupancy, the researchers noted.Lately, airlines have abandoned the pandemic practice of blocking seats to maintain physical distancing between the travellers"Physical distancing of airplane passengers,.