The Covid-19 vaccines have not only been tested on healthy people as claimed

28 May 2021
What was claimed

People who were undergoing chemotherapy have been told that they should not receive vaccines, and should stay away from people who had received vaccines, and now because of Covid-19 this has all changed.

Our verdict

People who are immunosuppressed are advised not to have live vaccinations and not to be in close contact with people who have received certain live vaccinations, but the Covid-19 vaccines in use in the UK are not live vaccines and people undergoing chemotherapy have been prioritised to receive them.

What was claimed

The Covid-19 vaccine was only tested on completely healthy people.

Our verdict

Incorrect. The trials of the Covid-19 vaccines did include groups of people with certain medical conditions. We are also finding out more about this through post authorisation monitoring.

What was claimed

The Covid-19 vaccines have been authorised on an emergency licence, because they are still in clinical trials.

Our verdict

Two of the vaccines have received temporary authorisation, and the Moderna vaccine has been issued conditional marketing authorisation. These classifications are regulatory tools to allow approval at the earliest time possible during an emergency situation, as soon as there is robust data to show that the benefits outweigh the risks.

A widely shared video on Facebook makes a number of claims about vaccines which are wrong or need more context.  

This article does not discuss all of them, but here are a few of the biggest claims made in the video. 

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“Up until now people who were undergoing chemo, not only were they told they could not receive vaccines, they had to keep well away from the newly vaccinated”

People who are undergoing or have recently had certain treatments, such as chemotherapy, or who are immunosuppressed for other reasons, are generally advised not to have ‘live’ vaccinations, or to be in close contact with people who have recently been immunised with certain live vaccinations.

Live vaccines contain whole bacteria or viruses which have been “weakened” so that they trigger an immune response without causing disease in healthy people. 

In clinically immunosuppressed people, however, there is a potential risk of infection if live vaccines are used. Similarly, immunosuppressed people are sometimes advised not to have close contact with other people who have recently had certain live vaccines because of a risk that they may be able to spread viral particles. We have written about this process, which is sometimes colloquially known as ‘vaccine shedding’, before. 

The Pfizer, AstraZeneca and Moderna Covid-19 vaccines that have received authorisations in the UK so far are not live vaccines, and therefore can be given to people who have recently received chemotherapy. In fact, people who are immunosuppressed have been included in priority groups for the Covid-19 vaccines.  


“It was only tested, for a very short time on completely healthy people. No polypharma users in the tests.”

The studies for all three of the Covid-19 vaccines currently authorised for use in the UK included cohorts of people with underlying health conditions, as well as ‘completely healthy people’ in the trials. 

Approximately 21% of the people included in Pfizer’s phase three trial, published in The New England Journal of Medicine, for example, had background comorbidity (meaning they had other medical conditions). These included a wide range of medical conditions such as cancer, cardiovascular problems and diabetes. 

A significant number of people given the AstraZeneca vaccine in phase three trials had underlying cardiovascular disease, respiratory disease, or diabetes. The Moderna trial also included people with underlying health conditions. 

Based on the research, and the increased risk that Covid-19 poses to people with certain underlying medical conditions, the World Health Organisation (WHO) has said that the Covid-19 vaccines are safe and effective for people with conditions such as high blood pressure; diabetes and asthma amongst others. People with underlying health conditions have also been included as a priority group for vaccination by the UK government. 


“The [Covid-19] vaccine has only been authorised by the MHRA on an emergency licence, which means it is in phase three clinical trials until 2023.”

Of the three Covid-19 vaccines that have been authorised for use in the UK, the Pfizer/BioNTech and Oxford-AstraZeneca vaccines have temporary authorisation (sometimes known as a regulation 174 authorisation) while the Moderna vaccine has conditional marketing authorisation.

All three of these vaccines  (Pfizer, AstraZeneca and Moderna) have had analysis of safety and efficacy data from phase three trials (involving tens of thousands of participants) published in peer-reviewed articles in medical journals such as The Lancet and the New England Journal of Medicine. The collection of long term protection and safety data will continue over the next couple of years, and so the completion dates for the trials are in 2022 and 2023.  

Normally, vaccines go through a process called marketing authorisation (also known as a licence). In certain scenarios, however, for example in response to “pathogenic agents”, the Medicines and Healthcare products Regulatory Agency (MHRA) may use different types of authorisation.

The MHRA told Full Fact that temporary authorisation and conditional marketing authorisations are “regulatory tools that enable medicines to be approved at the earliest time possible during an emergency situation, as soon as there are robust data to show that the benefits outweigh the risks [...]”

The MHRA also expanded on the differences between the two types of authorisation. It explained that a regulation 174 or temporary authorisation is not the same as a licence, instead “it authorises the emergency supply of an unlicensed medicine in response to an unmet public health need [and is] triggered by the Government, whereas conditional authorisation is applied for by the company.” 

It also explained that a conditional marketing authorisation (CMA), which the Moderna vaccine has, “is an early, temporary licence for a medicine where there is an unmet health need [...] CMAs are reviewed on an annual basis and can be converted into a full marketing authorisation but authorisations under Regulation 174 cannot,” though that doesn’t mean Pfizer or AstraZeneca would be prevented from applying for a change to the authorisations for their Covid-19 vaccines in the future.

Ultimately, the MHRA said: “Our rigorous review of the safety, quality and effectiveness of COVID-19 vaccine candidates is the same for both routes and no vaccine would be authorised via a CMA or R174 unless the expected high standards are met.”

The MHRA has said that the trials for the Covid-19 vaccines have proceeded “without compromising any of the usual, high standards of scientific rigour [...] tens of thousands of subjects have been included in trials and all are subject to very close safety follow-up over several months.”

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