"There is a growing body of research about how celebrity behaviour and social media posts can affect public health," Myrick said in the study published in the journal Health Communication.

"Celebrities can have a huge reach, often more so than typical scientists or doctors or the health department. If they are encouraging positive health behaviour change, then it can serve as a de facto public health intervention," Myrick added.

According to the study, the people who had heard the news reported Hanks' diagnosis "highlighted the reality of Covid-19" and broadened their understanding of not only the severity of the situation but also their susceptibility to the illness.

Nearly half of the participants who had heard the news when surveyed reported a range of emotional responses, according to the study.

Responses included "surprise, fear, anger, sadness and hope."

The respondents who reported making changes said Hanks' disclosure inspired them to seek more information and/or take stricter precautions.

The half of respondents who heard the news and said Hanks' diagnosis did not change their thoughts or behaviours reported thinking the actor would recover from the illness.

They also noted they were already aware of Covid-19 and its effects and did not think Hanks' announcement changed their outlook or intentions regarding the virus.

The researchers conducted a statistical analysis to see if and what characteristics could predict whether people's attitudes and behaviours changed after learning Hanks' diagnosis.

The results indicated that people who identified with Hanks or said they knew him were more likely to change their thoughts or Covid-related behaviours due to the announcement.