In this photo provided by El Salvador's presidential press office, airport workers unload a container of Chinese-made Sinovac COVID-19 vaccines from The New England Patriots team plane at the airport in San Salvador, El Salvador, late Tuesday, May 18, 2021. (El Salvador's presidential press office via AP)

In this photo provided by El Salvador's presidential press office, The New England Patriots team plane is parked on the tarmac of the airport in San Salvador, El Salvador, late Tuesday, May 18, 2021. The team plane has delivered Chinese-made Sinovac COVID-19 vaccines. (El Salvador's presidential press office via AP)

In this photo provided by El Salvador's presidential press office, China's ambassador to El Salvador Ou Jianhong speaks during a ceremony to receive containers of Chinese-made Sinovac COVID-19 vaccines, transported by The New England Patriots team plane, behind, at the airport in San Salvador, El Salvador, late Tuesday, May 18, 2021. (El Salvador's presidential press office via AP)