Vials of Pfizer’s COVID-19 vaccine are pictured at Rady Children’s Hospital in San Diego in December. Mexicans have gone to California, Florida and other states seeking vaccines as their country has struggled to roll them out.

Pfizer’s Covid-19 vaccine is pictured at Rady Children’s Hospital before it’s placed back in the refrigerator in San Diego, California on December 15, 2020. (Photo by ARIANA DREHSLER / AFP) (Photo by ARIANA DREHSLER/AFP via Getty Images)