The Daily Star published a story claiming the 20-year-old Italian striker filmed himself partying and sent clips to a private Snapchat group.
A statement from Premier League club Everton said: "Everton are appalled to learn of an incident in which a first-team player ignored government guidance and club policy in relation to the coronavirus crisis.
"The club has strongly expressed its disappointment to the player and made it clear that such actions are completely unacceptable.
"The amazing people in the NHS deserve the utmost respect for their hard work and sacrifice.
"The best way to show them respect is by doing everything we can to protect them."
The Premier League season was suspended last month due to the spread of COVID-19, which has killed over 20,000 people in the United Kingdom.
Starting up front in Dusan Vlahovic's continued injury absence, Kean opened the scoring just before half-time with a neat 20-yard lob.
The in-form Italy international then netted his fifth goal in as many games in the 54th minute to make sure of Massimiliano Allegri's side's sixth successive league win – the margin widened further by Arkadiusz Milik's late third.
Victory maintained Juve's hold over Lazio – who have won only two of the past 36 editions of this fixture – and ensured the Bianconeri carry momentum into the World Cup break.
Kean was a threat from the outset, drilling just wide of the far post.
Nicolo Fagioli then called Ivan Provedel into action from distance, while Milik brilliantly controlled a long ball before bending a 20-yard effort marginally wide of the target.
The hosts broke through two minutes before half-time. Adrien Rabiot robbed Sergej Milinkovic-Savic of possession before his precise lofted ball found Kean, who neatly lifted over the advancing Provedel.
Lazio arrived in Turin having conceded just one away league goal this season, but Provedel was beaten again nine minutes after the restart, with Kean tucking into an empty net after the Biancocelesti goalkeeper parried Filip Kostic's initial effort.
The visitors struggled to pose a genuine threat at the other end. Wojciech Szczesny comfortably saved tame efforts from Luis Alberto and Pedro, before Milik turned home Federico Chiesa's inviting centre to cap a fine Juve win.
Kean had not scored since April, but the striker set Juve on their way to victory with an early strike at the Allianz Stadium.
Weston McKennie doubled the Bianconeri's lead with his first Serie A goal of the season, heading home in the second half, and Rabiot added a late double to cap an impressive performance.
That is now back-to-back wins for Massimiliano Allegri's side, who moved up a place to seventh ahead of a must-win Champions League clash at Benfica next week.
Juve started with great intensity and were rewarded just eight minutes in when Filip Kostic whipped in a cross from the left and an unmarked Kean applied the finish from close range.
Kean should have found the net again just after the half-hour mark but headed a McKennie cross wide from six yards out.
The Bianconeri demonstrated the danger they pose from set-pieces to double their lead nine minutes into the second half, McKennie rising to powerfully head Juan Cuadrado's delivery into the roof of the net.
Kean nodded in another sublime Kostic delivery but had his celebrations cut short after straying offside as hungry Juve continued to cause problems.
Juve scored another goal from a Cuadrado corner after 82 minutes, Guglielmo Vicario unable to palm away Rabiot's header before it crossed the line.
The France midfielder then capped a great evening for the Turin giants when Danilo's cross gave him a tap-in at the end.
Ronaldo left Juve before the transfer window closed, re-joining Premier League giants Manchester United after asking for a move away from Turin.
After Ronaldo departed Juve, the Serie A powerhouse – who were dethroned by Inter in 2020-21 – brought Kean back to the club from Everton on a two-year loan with an obligation to buy.
"When Cristiano told us he wanted to leave, we immediately thought of anticipating the future," Cherubini told Tuttosport in an interview that will be published in full on Friday.
"Kean is not the replacement of the Portuguese striker, but one of the pawns in a plan to continue winning with a different project."
During his time at Allianz Stadium, Ronaldo scored 101 goals across 134 matches in all competitions.
Ronaldo topped the goalscoring charts with 29 Serie A goals last season but Juve finished fourth in Andrea Pirlo's first campaign at the helm.
Pirlo was sacked as a result, with Juve turning to former head coach Massimiliano Allegri, who have only collected one point from their opening two fixtures of the 2021-22 season.
Neymar was called up by Brazil for the 2022 World Cup qualifiers against Venezuela and Uruguay despite missing PSG's previous three matches.
However, the former Barcelona forward will not recover in time to feature for his country during this month's international break, Brazil unwilling to take any risks with his fitness.
PSG confirmed on Friday that Neymar is to head back to the French capital as part of the "trust and collaboration" between the staff at the Ligue 1 champions and the Selecao.
Meanwhile, Kean is already back amid reports in the Italian media he is dealing with a muscle issue.
The striker, who has scored five goals in seven appearances since his arrival on loan from Everton, will miss Italy's upcoming Nations League games against Poland and Bosnia-Herzegovina.
PSG are back in action on November 20, taking on Monaco in the league. They then host RB Leipzig four days later in the Champions League, having lost the reverse fixture in Germany.
Sassuolo were much the better side in the first half of the Serie A clash at MAPEI Stadium – Citta del Tricolore on Monday and they were rewarded when Giacomo Raspadori put them in front.
Paulo Dybala equalised on the stroke of half-time, though, and substitute Kean's first goal for two months in the 88th minute snatched a huge win for the Bianconeri.
Juve remain in fourth place with four games to play, eight points better off than Roma in fifth spot and just one behind Napoli.
Raiola's family announced he passed away on Saturday, two days after it was revealed the Italian was in a critical condition in San Raffaele Hospital in Milan.
One of the most recognisable agents in the world, Raiola represented the likes of Haaland, Zlatan Ibrahimovic, Paul Pogba and many more.
Borussia Dortmund striker Haaland reacted to Raiola's death by posting a picture of the two of them along with a heart emoji and wrote: "The best."
On-loan Juventus striker Moise Kean also paid an emotional tribute to his agent.
He posted on Instagram: "I still can't believe, you took me out from the streets and you made me learn so many principles in life… to be honest it's not a not goodbye for us wherever you are you will always be in my heart . R.I.P BIG Boss."
Raiola's family said in a statement: "In infinite sorrow we share the passing of the most caring and amazing football agent that ever was.
"Mino fought until the end with the same strength he put on negotiation tables to defend our players. As usual, Mino made us proud and never realised it.
"Mino touched so many lives through his work and wrote a new chapter in the history of modern football. His presence will forever be missed.
"Mino's mission of making football a better place for players will continue with the same passion.
"We thank everybody for the huge amount of support received during these difficult times and ask for respect to the privacy of family and friends in this moment of grief."
