Prince Philip praised the "vital and urgent work" being done by key workers helping keep Britain moving during the coronavirus pandemic in his first message since retiring.
The Duke of Edinburgh, 98, wrote the message to mark World Immunisation Week.
It's the first time he's shared a solo message since he stepped back from his royal duties in 2017.
He is currently following self-isolating and social distancing guidelines along with the Queen at Windsor Castle.
In the message, he writes: "As we approach World Immunisation Week, I wanted to recognise the vital and urgent work being done by so many to tackle the pandemic; by those in the medical and scientific professions, at universities and research institutions, all united in working to protect us from Covid-19.
"On behalf of those of us who remain safe and at home, I also wanted to thank all key workers who ensure the infrastructure of our life continues; the staff and volunteers working on food production and distribution, those keeping postal and delivery services going, and those ensuring the rubbish continues to be collected."
Despite retiring in 2017 the Duke remains affiliated to more than 750 organisations, including the scientific, technological research, healthcare and infrastructure sectors, which have responded to the outbreak.
Some of his associations include the London School of Hygiene and Tropical Medicine, where experts are involved in many different aspects of research as well as providing guidance to those responding around the globe every day. Philip has been Patron since 1952.
The Queen and Prince Philip are in the 'high risk' coronavirus group.
Dr Anna Hemming, who spent seven years as The Firm's resident medic, previously said: "Clearly, members of the Royal Family are in high risk groups - not just over 70 but over 90 years old too.
"I believe the family will be talking daily with their medical team and taking all reasonable precautions, particularly for the Duke of Edinburgh who we are all aware is the most fragile member of the Royal Family."
Prince Philip has suffered various health conditions in recent months and is being sheltered.
The Duke of Edinburgh was flown by helicopter to Windsor Castle from the Sandringham estate where he had been staying in his secluded Wood Farm cottage.
