BUENOS AIRES — President Alberto Fernández of Argentina had an initial positive test for Covid-19 and is awaiting the results of a more precise analysis to determine whether he has contracted the coronavirus despite being vaccinated earlier this year.
Mr. Fernández sent a series of tweets early Saturday morning saying he took a quick antigen test after suffering from a “light headache” and having a fever of 99.1 degrees.
The president, who received the test result on his 62d birthday, said he will remain in isolation while waiting for the results of the more rigorous PCR test.
“I am physically well, and although I would have liked to end my birthday without this news, I’m also in good spirits,” the president wrote on Twitter.
What sets Mr. Fernández apart from those leaders is that he appears to be the first to test positive for Covid-19 after having been fully vaccinated.
Mr. Fernández received the first dose of Russia’s Sputnik V vaccine on Jan. 21 and the second dose on Feb. 11.
Russia’s Gamaleya Institute, which developed Sputnik V, wished the president well and said that while the vaccine has an efficacy rate of 91.6 percent, it is fully effective in preventing critical cases.
“If the infection is indeed confirmed and occurs, the vaccination ensures quick recovery without severe symptoms,” the institute wrote in a statement on Twitter. “We wish you a quick recovery!”
Word of Mr. Fernández’s test result comes shortly after Argentina tightened its borders amid an upsurge of Covid-19 infections. Several of its neighboring countries, particularly Brazil, are experiencing a sharp increase in cases as new, more contagious variants of the virus engulf the region.
Argentina recently canceled all direct flights with Brazil, Chile and Mexico in an effort to block the new strains.
Argentina was the first country in Latin America to approve the use of the Sputnik V vaccine in late December, but mass inoculations are taking longer than the government had initially predicted amid a global shortage of the vaccine. It has also been administering China’s Sinopharm vaccine and Covishield, the Indian version of the AstraZeneca vaccine.
Of the nation’s 45 million people, 683,771 have received two vaccine doses, and there have been 4.18 million doses injected over all.
Argentina said on March 26 it would delay applying the second dose of the Covid-19 vaccine for three months in an effort to ensure as many people as possible get at least one dose. The country has reported nearly 2.4 million Covid-19 infections and more than 56,000 deaths.
