Former Pope Benedict XVI on Thursday celebrated his 93rd birthday under strict isolation at home due to the novel coronavirus pandemic.

Benedict, who has been living in a monastery within Vatican grounds since retiring seven years ago, has stopped contacts with the outside world to minimise contagion risks.

“We live under ‘house arrest’ like so many people in Italy, and though thank goodness everybody is doing well, of course there are no visits,’’ his private secretary, Archbishop Georg Gaenswein, told Vatican News.

However, a surprise is planned for the retired pontiff.

Gaenswein said he would be given an advance copy of his new biography, a 1,100-page “magnum opus” by Peter Seewald, a German author who already published several book interviews with Benedict.

“Benedikt XVI: Ein Leben” (Benedict XVI: A Life) is due out on May 4.

In the past years, Benedict celebrated his birthdays with a delegation from his home German state of Bavaria, including his 96-year-old brother Georg Ratzinger, also a priest.

In 2019, Pope Francis paid Benedict a visit on the eve of his birthday.

Benedict XVI was formerly known as Cardinal Joseph Ratzinger of Germany.

In 2013, he became the first pope to resign in almost 600 years.