Washington, Jan 3 : US Secretary of Defense Lloyd Austin announced that he has tested positive for Covid-19 despite being fully vaccinated and having also received a booster dose. In a series of tweets late Sunday, Austin said: "I tested positive this morning for Covid-19. I requested the test today after exhibiting symptoms while at home on leave. My symptoms are mild, and I am following my physician's directions. "As my doctor made clear to me, my fully vaccinated status Â? and the booster I received in early October Â? have rendered the infection much more mild than it would otherwise have been. And I am grateful for that. "The vaccines work and will remain a military medical requirement for our workforce. I continue to encourage everyone eligible for a booster shot to get one. This remains a readiness issue." In a separate statement, the Secretary of Defense added that he has "informed my leadership team of my positive test result, as well as the President". "My staff has begun contact tracing and testing of all those with whom I have come into contact over the last week." The Secretary said he last metPresident Joe Biden on December 21, 2021 and "tested negative that very morning". He has not been in the Pentagon since December 30, 2021, when he met briefly with a few members of his staff, during which they "were properly masked and socially distanced throughout", Austin's statement said. /IANS