"Ten thousand is still fairly low by Chinese standards," she added.
China is home to more than 10 million Catholics, with six million registered as members of the Chinese Catholic Patriotic Association, according to official statistics.
"Often the sensitivities surrounding officially recognized religions and even other groups in China are triggered by growing popularity," Cook said. "My sense is that if the broadcasts had continued and began reaching an even bigger audience, say hundreds of thousands or a million people, then it would have been shut down at some point."
"Crackdowns on other religious groups and even information sharing or online preaching have continued amid the pandemic," she added, particularly for Protestants and other persecuted religious groups in China, such as the Falun Gong.
During the coronavirus pandemic, the human rights group Voice of the Martyrs reported that government officials in Shandong Province banned online preaching amid the outbreak, and the Christian non-profit ChinaAid shared a video March 15 of a Protestant church in Jiangsu Province that had been demolished by Chinese authorities.
The Chinese government has also used social media platforms to help monitor and detain Muslims in China's Xinjiang Uyghur Autonomous Region.
Data showing which WeChat users followed the pope's livestream Mass could be accessed by the Chinese government in the future, Cook acknowledged, while noting that "Catholicism is an approved religion in China and most people don't run into trouble for attending Mass at a state-sanctioned church."
"With improving relations between the Chinese government and Vatican, I imagine that the pope is not as sensitive a figure as he previously was. So I don't imagine people would get in trouble just for watching this," she said.
Among the government regulations of the state-sanctioned Catholic churches in China is a prohibition on minors under the age of 18 from entering church property.
Cook noted that while children could be seen praying in the Vatican News video, this is "one part of religious regulations that has often slipped through the cracks in the past in terms of enforcement, so that may be the case now."
A report by the U.S. China Commission in January found that Chinese Catholics suffered "increasing persecution" after the Vatican-China deal. It said the government was "demolishing churches, removing crosses, and continuing to detain underground clergy." Priests and bishops have reportedly been detained or have gone into hiding.
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In February, Archbishop Paul Gallagher, the Vatican Secretary for Relations with States, met with the Chinese foreign minister Wang Yi on the sidelines of the Munich Security Conference. The Holy See press office reported that the meeting was an occasion for "renewing the willingness to continue the institutional dialogue" between the Holy See and the Chinese Communist Party.
The Jesuit magazine La Civiltà Cattolica announced in April that it was launching a version in simplified Chinese.
Vatican Secretary of State Cardinal Pietro Parolin, praised the decision to launch the Chinese edition in a letter to La Civiltà Cattolica.
"I can only express from the depths of my heart my warmest best wishes and the fervent hope that your Chinese language edition might become a solid instrument of mutual cultural and scientific enrichment, among all people in search of beauty and truth," Parolin said.
The first papal liturgy to be viewed over WeChat in China was Pope Francis' extraordinary Urbi et Orbi blessing on March 27 for the world suffering from the coronavirus pandemic.
Vatican News reported that in China the news that the live broadcast of the pope's Mass would end on May 18 was "greeted with some suffering and also with some tears."