Anthony Fauci, the face of the US government’s fight against the Covid pandemic, is recovering at home after a hospital stay with West Nile virus.

The immunologist and former chief medical adviser to the president was hospitalized about 11 days ago with the mosquito-borne disease and had been suffering from fever, chills and fatigue.

He left the hospital earlier this week and is expected to make a full recovery. The BBC’s American media partner, CBS, reports.

Dr. Fauci, 83, told CBS he likely contracted the virus from a mosquito bite in his yard.

According to the U.S. public health agency Centers for Disease Control and Prevention (CDC), most people infected with West Nile virus do not become ill, but about one in five develops symptoms.

According to the CDC, the virus spreads to people when mosquitoes bite infected birds and then people.

There is currently no vaccine for the virus. It can be fatal in rare cases.

Fauci, the former director of the National Institute of Allergy and Infectious Diseases, retired in 2022.

He has said before that he and his family receive death threats and now require 24-hour security.

Some have criticized him for his handling of the Covid pandemic.

The leading immunologist was dragged before Congress earlier this year by Republican politicians, over allegations that he tried to cover up indirect U.S. funding for the Wuhan Institute of Virology, the Chinese lab believed by some to be linked to the emergence of Covid-19.

Dr. Fauci called the allegations false and said they were politically motivated because of his public disagreements with former President Donald Trump at the height of the pandemic.