The American TV network said the jabs were mandatory for all staff, saying it had a "zero-tolerance" policy toward unvaccinated workers.
Three people employed by American broadcaster CNN have been fired after the company discovered they had been coming to work while unvaccinated against COVID-19.
CNN staff were informed of the sackings in a memo sent out on Thursday by network boss Jeff Zucker, who said that COVID-19 vaccines were mandatory for all staff working from CNN offices or at external locations in close proximity to other CNN employees.
"Let me be clear — we have a zero-tolerance policy on this," wrote Zucker, chairman of news and sports for CNN's parent company WarnerMedia.
In July, Big Tech firms Alphabet and Facebook told workers that they would have to get vaccinated before they came back to the office.
Streaming giant Netflix reportedly also made vaccines mandatory for cast and crew on all its US-based productions.
Are mandatory COVID vaccinations the future?
While numerous American companies have mandated COVID-19 jabs for their staff, the picture in Europe is somewhat different.
From November 11, staff working at care homes in the United Kingdom will have to be vaccinated against the virus unless they can prove they have a medical exemption.
In July, French president Emmanuel Macron announced that coronavirus vaccines would become mandatory for all health and social care workers in France on September 15.
But outside of these specific cases, it can be very difficult for an employer in Europe to force their employee to either get jabbed, or even say whether they've been vaccinated or not.
'Think hard about it'
Last month, Professor Catherine Barnard, an expert in European Union and labour law at Cambridge University, said that one key difference was the relative strength of European workers' rights, compared to those in the US.
"The legal risks for employers are that they face unfair dismissal claims from employees and discrimination claims - disability discrimination and or possibly philosophical belief discrimination," she told Euronews Next.
"There is no guarantee that employees will win, but there is a chance, and this will make employers think hard about requiring all staff to be vaccinated".