Spotify has said it will add “content advisories” to episodes of Joe Rogan’s podcast discussing Covid after the singers Neil Young and Joni Mitchell accused the streaming service of helping to spread Covid misinformation.

The musicians are critical of Rogan, who has recently sparked controversy over comments made by himself and some of his guests about the pandemic.

So, what does the science say about some of Rogan’s most controversial claims?

’Healthy young people don’t need a Covid vaccine’

Rogan has claimed he isn’t anti-vaccine, but during a 23 April 2021 episode of his podcast he said: “If you’re like 21 years old, and you say to me, should I get vaccinated? I’ll go, no.”

Although it’s true that older people are at greater risk of severe disease and death, younger people can and do die from Covid-19. According to the latest UK Health Security Agency (UKHSA) figures, there have been 39 deaths in 20- to 29-year-olds with laboratory-confirmed Covid in England since January 2021.

Among those aged 30-39, there have been 185 deaths during the same period. That’s lower than the 18,931 deaths in people aged 80+, but not insignificant.

“Young people still get severe illness from Covid-19, and the benefits, directly to the young person, purely in terms of their risk of serious illness are much greater than any risks from vaccination,” said Dr Richard Tedder, a member of the UK Clinical Virology Network.

Separate research on 73,197 UK adults who were admitted to hospital during the pandemic’s first wave found that 27% of 19- to 29-year-olds suffered damage to their kidneys, lungs or other organs as a result of Covid-19, while 13% left hospital with a reduced ability to care for themselves.

‘The myocarditis risk is higher from vaccines than from Covid’

In his 12 January 2022 episode, Rogan claimed the risk of myocarditis (heart muscle inflammation) among vaccinated 12- to 17-year-olds was higher than the risk associated with catching Covid.

But his guest, the Australian broadcaster Josh Szeps, argued that, in fact, young males infected with the virus were up six times more likely to develop myocarditis as those who had received the vaccine. Szeps cited data from the US Advisory Committee on Immunization Practices, suggesting a rate of about 450 myocarditis cases in every million Covid-19 infections among boys aged 12-17, compared with 77 cases a million after vaccination.

Separate data from 38.6 million people aged 16+ who were vaccinated in England identified an extra two to six myocarditis cases in every million people in the 28 days after receiving a first dose of the AstraZeneca, Pfizer or Moderna vaccines, and an extra 10 cases a million after a second dose of the Moderna vaccine.

This compared with an additional 40 cases a million people in the 28 days after a positive Covid test.

“The risk of myocarditis is substantially higher following Covid infection than vaccination in the general population, but remains very infrequent following either,” said Nicholas Mills, a British Heart Foundation professor of cardiology at the University of Edinburgh, who was involved in the study.

“The majority of reports suggest that when it arises following vaccination it is mild and self-limiting.”

’Ivermectin can drive this pathogen to extinction’

During his 18 June 2021 podcast, Rogan’s guest, the evolutionary biologist Bret Weinstein, claimed that “ivermectin alone, if properly utilised, is capable of driving this pathogen to extinction”. On 2 September, Rogan announced that he had tested positive for Covid-19 and was also taking the anti-parasitic drug. Although he recovered, ivermectin is unlikely to explain why: according to a recent Cochrane Review, which analysed data from multiple studies, there is no evidence to support the use of ivermectin either for preventing or treating Covid.

“Because of a lack of good-quality evidence, we do not know whether ivermectin administered in hospital or in an outpatient setting leads to more or fewer deaths after one month when compared with a placebo or usual care,” its authors said.

‘mRNA vaccines are gene therapy’

In his 20 August 2021, podcast, Rogan claimed the Pfizer and Moderna Covid-19 vaccines were not really vaccines, but gene therapy. “A vaccine is where they take a dead virus, and they turn it into a vaccine, and they inject it into your body so that your body fights off [the infection],” he said. “This is really gene therapy. It’s a different thing. It’s tricking your body into producing spike protein and making these antibodies for Covid.”

It’s true that mRNA vaccines persuade our own cells to manufacture the viral spike protein, which in turn prompts the production of antibodies. However, whereas gene therapy is designed to permanently alter an individual’s genes, mRNA vaccines issue instructions to protein-making machinery located in the cytoplasm, which degrade after about 72 hours.

Because immune cells are able to remember pieces of virus they’ve encountered, this temporary encounter still has a lasting effect, but it doesn’t alter our genome.

Other types of vaccines, such as the influenza or hepatitis B vaccine, also expose the immune system to viral proteins, albeit pre-assembled ones.

“I’m not gonna get vaccinated. I have antibodies, it doesn’t make any sense.”

On 24 December 2021, Rogan told the US comedian Tim Dillon that his Vancouver show had been cancelled because Canada required proof of vaccination to attend live events.

Referencing his earlier Covid infection, Rogan said “I’m not gonna get vaccinated. I have antibodies, it doesn’t make any sense.”

Although so-called natural immunity is likely to provide some protection against subsequent infection, vaccination would strengthen and extend the duration of that response.

Tedder said: “About one in five people who get Covid do not generate a useful immune response, and those who do gain a valuable ‘booster’ effect if they are subsequently vaccinated, deepening and enhancing their immune response so that it lasts for longer, and is better able to recognise new variants.”

Lockdowns ‘make things worse’

Rogan has also spoken out against lockdowns, arguing that they can perpetuate the spread of Covid-19. “It makes things worse, you know why – because people go inside. They are trapped inside and that’s where it spreads,” he said.

However, according to an analysis of the impact of lockdowns and social distancing in 11 European countries, published in Nature, such measures together have a “substantial effect” on transmission.

“It is true that, since the virus is airborne, transmission is more likely indoors, particularly if ventilation is poor; but the point of lockdowns is to reduce the number of contacts, and thus the likelihood of encountering somebody who is infectious,” Tedder said.