Alvarez is eligible to represent both teams and has received separate calls to join the USMNT and El Tri for various competitions. After being included in both nations preliminary squads for the CONCACAF pre-Olympic qualifying tournament, Alvarez ultimately accepted a selection from Mexico's senior squad ahead of friendlies against Wales and Costa Rica.
Despite the consideration from both countries and the high praise received from officials on both sides, the most recent experience has left a negative impact on the player, according to his father, Crescencio Alvarez.
"These are very tough decisions because the federations are 'traumatizing' him because they're calling him in at the same time," the elder Alvarez said in an interview with TUDN. "Wherever he decides to play, we're going to support him."
Efrain, who was born in Los Angeles, has already represented both nations in different youth categories. After competing for the U.S. at the under-15 level, Alvarez played in the under-17 World Cup for Mexico in 2019, notching a second-place finish.
Despite currenlty training with the Mexican senior team, the 18-year-old is still eligible to file a one-time switch back to the United States in accordance with FIFA's statutes.
"I don't want my son to blame me for picking [one of the two national teams], he's an adult now," the elder Alvarez said.
The confusion as to whether Efrain would remain with Mexico or play for the United States earlier this month prompted an uproar on social media, his father added, with people "attacking him and saying bad things about him."
While USMNT coach Gregg Berhalter has said he approved of Alvarez accepting Mexico's senior team call to compare both squads and their respective environment, Mexico's under-23 manager Jaime Lozano also spoke plainly about the competitive landscape between both nations in their pursuit of dual national players.
"There are some [players] who see themselves as more American than Mexican, and that's respectable," said Lozano in a news conference on Tuesday. "That's the battle Mexico wages with the United States, to keep these players, you have to be sincere with them and allow the players to choose," he continued.
Lozano's team will face the United States in a group stage match on Wednesday at the pre-Olympic qualifying tournament, although the two teams are officially through into the semifinals. The winners of the two semifinal matches will book their tickets to the Tokyo Games this summer.
Both the U.S. and Mexico squads at the tournament in Guadalajara feature players who are ultimately eligible to represent the other nation. Mexico's Santiago Munoz was born in El Paso, Texas, while David Ochoa, Julian Araujo, Sebastian Saucedo and Sebastian Soto from the United States are all eligible for El Tri through their parentage.