With Italy in lockdown as the country attempts to deal with the COVID-19 pandemic, Ronaldo insisted the protection of human life must be the main focus at a time of huge disruption to the sporting calendar.
Ronaldo's Juve team-mate Rugani is in isolation after it was announced he had tested positive, with the number of confirmed global cases now over 132,000.
Rugani was in the Portugal international's thoughts as he posted on social media to discuss the recent developments surrounding coronavirus.
Ronaldo's post came on a day where the Premier League and Bundesliga became the latest leagues to postpone matches amid a host of other cancellations across the world, with the Champions League and Europa League also off next week.
"The world is going through a very difficult moment which demands the utmost care and attention from all of us," Ronaldo, 35, wrote while also posting a World Health Organization (WHO) link containing information on the virus.
"I speak to you today not as a football player but as a son, father, a human being concerned with the latest developments that is affecting the whole world.
"It is important we all follow the advice of the WHO and the governing bodies on how we handle this current situation. Protecting human life must come above any other interests.
"I would like to send my thoughts to everyone who has lost someone close to them, my solidarity to those who are fighting the virus like my team-mate Daniele Rugani, and my continued support to the amazing health professionals putting their own lives at risk to help save others."
Juve confirmed on Wednesday that Rugani had contracted for the COVID-19 virus, which originated in the Chinese city of Wuhan in December.
Rugani was an unused substitute on Sunday, as Juve saw off Inter 2-0 in a top-of-the-table clash played behind closed doors.
Following Juve's announcement over Rugani, Inter confirmed they will suspend all competitive activities until further notice.
The World Health Organisation (WHO) has now declared the spread of the illness as a global pandemic, with people urged to self-isolate for 14 days if they have come into contract with someone suffering from the virus.
Italy has responded strongly to the outbreak, with the country placed on lockdown and the government having now suspended all domestic sport until April 3.
Rugani tested positive for COVID-19 but is not displaying any symptoms, Serie A champions Juve revealed on Wednesday.
The 25-year-old contracted the virus following last week's clash with rivals Inter, and just six days before Juve are scheduled to play Lyon in the second leg of their Champions League last-16 tie.
"You will have read the news and that's why I want to reassure all those who are worrying about me, I'm fine," Rugani wrote via social media.
"I urge everyone to respect the rules, because this virus makes no distinctions! Let's do it for ourselves, for our loved ones and for those around us #thankyou."
No country outside China has been more heavily affected by the virus, which originated in Wuhan in December and was on Wednesday confirmed as a pandemic by the World Health Organisation (WHO).
Italy has responded strongly to the outbreak, with the country placed on lockdown by its government and suspending all domestic sport until April 3.
According to the WHO, Italy has more than 12,000 confirmed cases of coronavirus and has seen over 800 deaths as a result.
Matuidi is the second Juve to be diagnosed with the virus after Daniele Rugani was confirmed as their first case last Wednesday.
Like Rugani, Matuidi's test has come back positive despite the player not developing any symptoms; however, he had already been in isolation since his team-mate's diagnosis.
A statement released by Juve read: "Blaise Matuidi has undergone medical tests that have revealed his positivity to the coronavirus-COVID-19.
"The player, as of Wednesday March 11, has been in voluntary home isolation. He will continue to be monitored and will follow the same regime. He is well and is asymptomatic."
Football in Italy is suspended until April 3 due to the pandemic, but Italian Football Federation (FIGC) president Gabriele Gravina has already suggested it is not realistic to expect action to resume at the start of next month.
Euro 2020 was due to start in Italy's capital Rome on June 12, but on Tuesday the tournament's postponement until June 2021 was confirmed by UEFA.
No country outside China has been more heavily affected by the virus.
COVID-19 was declared pandemic last week and has affected 196,000 people worldwide, with just under 32,000 cases recorded in Italy, where 2,503 deaths have occurred.
Rugani was among the first wave of high-profile confirmed cases in Serie A when he tested positive for COVID-19 last month.
Matuidi followed as Juve's second case, although neither player developed symptoms.
A month on, the duo have each returned two negative tests.
The Bianconeri's statement read: "The players have, therefore, recovered and are no longer subjected to the home isolation regime."
The duo have not missed any action as Serie A has been suspended amid the pandemic.
The Italian Football Federation (FIGC) is looking to resume the season in the coming months, however.
FIGC president Gabriele Gravina has praised Juve for their apparent stance against being awarded the Scudetto as they top the table at the time of the pause in play.
Maurizio Sarri's men are a point clear of second-placed Lazio with 12 matches remaining.
Rugani said he was "fine" despite testing positive for the virus with Juve confirming on Thursday that 121 people connected to the club - including players and directors - are undergoing voluntary isolation.
The club's Champions League last-16 tie with Lyon has been postponed as European football continues to respond to the pandemic, which has killed over 1,000 people in Italy.
Juve donated €300,000, jointly given by the club and players, to begin the fundraising efforts, with money set to go to the 'Piedmont Region-Coronavirus emergency support' initiative.
Club chairman Agnelli asked fans in a video released via social media to donate to the fundraiser, which is hosted on the GoFundMe website.
"In this moment of a medical state of emergency, we too, as Juventus, want to make our contribution," Agnelli said.
"First of all, by respecting the rules and asking everyone to do the same: stay home.
"Since yesterday, I too am observing a period of voluntary isolation, but we have to and want to do more.
"And that's why, along with our players, we have launched a fundraising campaign to support our healthcare professionals in our neighbourhoods - in Turin and Piedmont.
"And that's why we ask you to contribute. In this difficult time, despite being distant, let's stay united and all together. We will get out of this delicate moment."
Juve are not set to play again until next month with all sporting activity in Italy suspended until April 3.
The reigning Serie A champions revealed on Wednesday Italy defender Rugani has contracted COVID-19 but is not displaying any symptoms.
A club statement read: "Juventus Football Club is currently activating all the isolation procedures required by law, including the census of those who have had contact with him."
Rugani tested positive for the virus six days before Juve are scheduled to play Lyon in the second leg of their Champions League last-16 tie.
People who come into contact with someone who has COVID-19 are advised to self-isolate for 14 days.
No country outside China has been more heavily affected by the virus, which originated in Wuhan in December and was on Wednesday confirmed as a pandemic by the World Health Organisation (WHO).
Italy has responded strongly to the outbreak, with the country placed on lockdown by its government and suspending all domestic sport until April 3.
According to the WHO, Italy has 10,149 confirmed cases of coronavirus and has seen 631 deaths as a result.
Rugani tested positive for COVID-19 last week – one of the key events in prompting a near-total shutdown of elite football across Europe.
Serie A is suspended until April 3 and a UEFA video conference on Tuesday will see clubs and national associations discuss how best to proceed with the Champions League, Europa League, Euro 2020 and domestic competitions amid the ongoing crisis.
In an interview with Juventus' in-house television channel, Rugani reported he had not suffered severe symptoms – such as respiratory problems – associated with the most serious cases of COVID-19.
"I want to reassure everyone by saying that I am fine," he said. "I have always been quite well. I have not had the serious symptoms mentioned.
"I consider myself lucky even if it was a heavy blow also because I was the first in our environment [and] served to raise the awareness of all those who had not understood the seriousness of the problem."
Rugani revealed he had been passing his time in isolation by watching drama series Peaky Blinders and reading the Harry Potter novels to improve his English, although he conceded being forced to spend time apart from his family was tough.
Asked what he had missed most from everyday life, the 25-year-old replied: "Embracing my loved ones.
"I am alone in the hotel and I will have to stay a little longer. The isolation is long and boring, for me as for everyone, so as soon as I go out, I will go to the people I miss and love."
Italy is the European country most affected by coronavirus, with 24,747 confirmed cases and 1,809 deaths.
The government has imposed strict lockdown measures, with public events and gatherings banned and all shops apart from food stores and pharmacies closed.
