In Mexican border cities people are concerned about folks from the United States bringing the novel corona virus to them. San Diego has three times the number of COVID-19 cases as Tijuana. The state of California has about 10 times more people than Baja to its south but 20 times the number of cases.
The US extended its border restrictions for a month this week and Mexico has imposed similar restrictions on nonessential traffic from the United States. But the border is still open to commercial traffic and people from the US are likely taking the virus to Mexico.