Anti-vaccine campaigners in the United States have come out in force against the three coronavirus vaccines that have proven effective in trials, amid a worsening pandemic that has killed more than 270,000 Americans and infected more than 13,7 million.

On Wednesday, the US also surpassed 200,000 new infections and more than 100,000 COVID-19 patients hospitalized, the first time either daily level has been reached.

The opposition to the vaccines comes as pharmaceutical companies Pfizer/BioNTech, Moderna, and AstraZeneca/Oxford are seeking emergency approval from the US Food and Drug Administration (FDA).

On Wednesday, the UK approved Pfizer Inc's COVID-19 vaccine, becoming the first Western country to approve widespread use of a vaccine.

The mistrust of vaccines and, more specifically the coronavirus vaccines, is international. Since March, mass protests have taken place in 26 countries including Germany, the UK, Brazil and in several US states.

So-called "anti-vaxxers" — those who oppose vaccines — are using Facebook and other social media sites, according to the Centre for Countering Digital Hate (CCDH), a London-based nonprofit that aims to disrupt identity-based hate and counter its growing influence in politics.

It found that 31 million people follow anti-vaccine groups on Facebook, and 17 million people subscribe to similar YouTube accounts. CCDH alleges that social media firms are reluctant to silence anti-vaccine accounts as they can generate $1 billion in annual revenue.

In May, a now-deleted YouTube video that claimed that vaccines would "kill millions" got more than 8 million views.

Soon after Pfizer/BioNTech announced in November that its vaccine had proved 90 percent effective, Bill Gates, the Microsoft founder, began trending on Twitter. Anti-vaccine groups said he wants to insert a chip into COVID-19 vaccines so he can track people's movements via 5G cellular networks.

US researcher Dr Judy Mikovits, who was behind a widely circulated anti-vaccine video called Plandemic, also blamed the coronavirus outbreak on Gates, big pharmaceutical companies and the World Health Organization (WHO).

Mikovits has claimed that Dr Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, was responsible for the deaths of millions from AIDS, and the video claims she was part of a team that discovered HIV and revolutionized HIV treatment.

The anti-vaccine movement also is rebranding its efforts with an emphasis on personal freedom and suspicion of government to exploit American reaction to the pandemic, said Dorit Reiss, a University of California Hastings law professor who specializes in policy issues related to vaccines.

More people are vulnerable, upset and distrustful, said Reiss, "and the anti-vaccine movement knows exactly what to say".

Jonathan M. Berman, a scientist and assistant professor in the basic sciences department at the New York Institute of College of Osteopathic Medicine at Arkansas State University, wrote a book called Anti-vaxxers, How to Challenge a Misinformed Movement. He believes that there are several reasons why wild conspiracy theories about COVID-19 vaccines are springing up online and elsewhere.

"The pandemic has created an environment where people have very little information about the vaccines and have lost a lot of control of their lives. Developing conspiracy theories helps people to regain a sense of control of their environment,'' he told China Daily. "They feel that they can find information that no one else has and can use that to make a decision.

"People are responding to some basic fears that almost everyone shares to a degree,'' Berman said. "People fear governments and corporations making decisions about their health. They fear putting things they view as ‘unnatural' into their bodies. They fear living in a complex world that does not conform to intuitive answers that make sense to them."

The Children's Defense Fund, chaired by Robert F. Kennedy Jr, is a non-profit that advocates for children's rights and encourages research on vaccines.

It warns: "More and more states — and many legislators from both political parties —are displaying a willingness to impose heavy-handed vaccine mandates that trample on religious, parental, and human rights — including the precious right to ‘security of person' guaranteed by Article 3 of the Universal Declaration of Human Rights."

In 2019, the WHO said that people's hesitancy to get vaccinated was one of the top 10 threats to global health.

Health officials suggest that at least 70 to 80 percent of the world's population must get vaccinated to quell the pandemic.

In May, a poll from The Associated Press-NORC Center for Public Affairs Research found that 31 percent of Americans were unsure if they would get the COVID-19 vaccine once released. However, a recent Gallup poll found that 58 percent of Americans are willing to get a COVID-19 vaccine.

Dr Peter Hotez is dean of the National School of Tropical Medicine at Baylor College of Medicine in Houston. As a vaccine scientist and autism parent, he has led national efforts to defend vaccines against the anti-vaccine movement.

In a 2019 article on the American Medical Association website, Hotez said that there isn't a "commensurate response" to the movement because "we need to hear more from our federal agencies about a strong pro-vaccine campaign or message" as well as from scientists.

"We're uniquely qualified to debunk misinformation and we now have to be willing to step outside of our laboratories and speak out on this because the American public is not hearing from our scientists," he said.