The central Mexican state of Guanajuato has responded to the need to strengthen sanitary safety measures involved in international and domestic travel following on from the US executive order to increase sanitary safety, due to Covid-19. New US president Biden had signed the new regulation on 21 January and, given that the US is the main source market for international tourists in Mexico, the Government of Guanajuato now requires that international travellers from Mexico submit a negative Covid-19 test prior to entry into the US. Tests can be performed up to 72 hours prior to travel at Guanajuato International Airport. The airport operator Grupo Aeroportuario del Pacífico (GAP) reported that, on 25 January, temporary modules were installed, and that the cost of the antigen test was set at 450 pesos (US$22) and for the PCR test 1,450 pesos (US$72) for passengers on international flights.