Yellow CARD analysis

Data is a precious thing and will last longer than the systems themselves.

– Tim Berners-Lee


Our analysis of the Medical & Healthcare products Regulation Agency (MHRA) Yellow Card Scheme for COVID-19 vaccines uses the publicly available reports that are released by the MHRA – initially weekly and then monthly.  Regrettably, the MHRA overwrites the report each time, so the only download available to the general public at any given time is the summary at that particular point.  Without access to preceding reports, the snapshot their document provides allows for little analysis.

Fortunately, we have downloaded and kept a copy of every report going back to the start of the COVID-19 vaccine rollout and have therefore been able to build a more detailed picture of how adverse reactions have developed over time.

The MHRA does a monthly “cut off” of data but then takes several days to make the summary report available on its website.  So at times we can be looking at information that is over a month out of date.  Given that millions were receiving vaccines each week, we are concerned that this time lag introduces additional risk as well as restricting the ability of an individual to make a truly informed decision about having the vaccine based on up to date risk information.

We are also hampered by incomplete data so have deliberately held back from drawing conclusions based on the data we have.  Instead, we aim to provide insights into what we do know so that we, and you, can ask more meaningful questions of the MHRA, the government, vaccine manufacturers – and your own healthcare providers.   

What We Do Know

What We Don't Know

* From November 2022, MHRA is issuing the data in a new format and we will be exploring whether we can glean any new insights

** From January 2023, MHRA is changing its reporting to only report on boosters administered from Autumn 2022. We will explore whether this new report will allow us to better analyse the boosters – if not historically, then at least going forward. 

Cause for Concern

As we began our first look at the week by week data, it came to our attention that Dr Tess Lawrie (MBBCh, PhD), of the Evidence-based Medicine Consultancy, was about to undertake a similar task.  We therefore reached out and agreed that we would pool our technical skills and her medical expertise to better understand and analyse the data.

An important discovery was that similar conditions had been classified in many different ways.  Dr Lawrie’s medical knowledge helped us to better group similar conditions together.  Once we did that, it became clear that there were far higher incidences of some reactions than a cursory glance of the MHRA report would suggest.

Dr Lawrie was so concerned about what she saw that she immediately presented the findings in an open letter to Dr June Raine, Chief Executive of the MHRA.  As well as presenting the findings, the letter also called for an immediate halt of the COVID-19 vaccine rollout until more detailed analysis of the Yellow Card data can be carried out. 

With the rollout continuing, Dr Lawrie sent a follow up letter in September 2021 highlighting even more concerns, particularly that the suspected deaths per million doses was 28 times higher than for the flu vaccines.   

Alas, as at January 2023, the mRNA vaccines are still being rolled out – and actively recommended by healthcare providers, government and the mainstream media – and the number of reactions and deaths attributed to them continue to rise.

Yellow Card Summary to 28th December 2022

In early January 2023, MHRA reissued the data to 23/11/22 in a new format, claiming it was the same data, however we have compared the two datasets and found an additional 83,056 reactions and 2 deaths in the reissued reports. We have made the assumption that the reissued dataset is the more accurate and therefore all charts reflect these figures going forward.
Pfizer/ BioNTech AstraZeneca Moderna Novavax Unspecified Totals
Rollout Start Date 08/12/20 04/01/21 07/04/21 03/02/22 n/a n/a
First Doses Administered* 27.2 million 24.9 million 1.7 million unknown n/a 53.8 million
Second Doses Administered* 25.0 million 24.2 million 1.6 million unknown n/a 50.8 million
Boosters Administered* 44.6 million 0.1 million 22.6 million 1,000 n/a 67.3 million
Adverse Reactions 554,990 933,236 164,502 327 8,664 1,661,719
Deaths 946 1,417 144 0 88 2,595

New reactions this report = 6,646

New deaths this report = 42

Data Source: MHRA

(as at 23/01/23 Novavax data from 23/11/22 to 28/12/22 is not included due to technical problems at MHRA)

How The Brands Compare

Due to the small quantities currently associated with the Novavax brand, they do not show up on the pie charts


Adverse Reactions


Due to the way MHRA has been reporting booster doses without a breakdown between the brands used, there is a growing disconnect between brand dosage numbers and adverse reactions. While booster doses are shown under "Unspecified", the likelihood is that people reporting a reaction are specifying which brand they received. It is therefore increasingly difficult to draw any meaningful conclusions. We still await an explanation as to why MHRA have not been reporting booster doses by brand in the same way they report first and second doses.
We understand that from January 2023, only third and subsequent dose volumes will be reported and these will be by brand, but until we have sight of that report some time in February we will not know whether the brand totals will include doses given historically. We will update this page once we know.

Top 20 Adverse Reactions

wdt_ID Condition No of Reactions No of Deaths
1 Headache 130,938 1
2 Fatigue 94,423 2
3 Pyrexia 92,140 1
4 Chills 64,217 0
5 Nausea 58,024 0
6 Pain in extremity 46,569 2
7 Myalgia 45,952 0
8 Dizziness 43,656 0
9 Arthralgia 41,488 0
10 Pain 33,199 0

Top 20 Causes of Death

wdt_ID Condition No of Deaths
1 Death (no further information available) 651
2 Pulmonary embolism 178
3 Myocardial infarction 146
4 Cardiac arrest 118
5 Cerebrovascular accident 91
6 Cerebral haemorrhage 89
7 Sudden death 84
8 COVID-19 77
9 Thrombosis 62
10 Pneumonia 59


wdt_ID Type of Reaction (System Organ Class) Reactions Deaths
1 Blood disorders 30,236 37
2 Cardiac disorders 35,300 489
3 Congenital disorders 294 6
4 Ear disorders 21,833 1
5 Endocrine disorders 1,095 1
6 Eye disorders 27,183 0
7 Gastrointestinal disorders 148,497 41
8 General disorders 462,675 812
9 Hepatic disorders 1,009 14
10 Immune system disorders 7,411 8

Vaccine Rollout by Week

Weeks with negative doses are not our error but are where the totals contained in the MHRA reports are lower than the preceding week. We do not know if this is due to a clerical error in the preparation of the current weekly report, a correction of clerical errors made in previous reports or a correction due to errors in the past reporting of doses to the MHRA.

Further analysis coming soon

In the meantime, if you'd like to find out more about COVID-19 vaccines, the Public Health England weekly surveillance reports may prove useful:

If you'd like to find out about adverse reactions recorded in other countries, here are some useful links:

Essential Context for Understanding this report

These reports contain a complete listing of all suspected adverse reactions that have been reported to the MHRA via the Yellow Card scheme for COVID-19 vaccines. This includes all reports received from healthcare professionals, members of the public, and pharmaceutical companies.

This information does not represent an overview of the potential side effects associated with the vaccines. A list of the recognised adverse effects of the COVID-19 vaccines is provided in the information for healthcare professionals and the recipient information here. Conclusions on the safety and risks of the vaccines cannot be made on the data shown in the report alone. When viewing the report, you should remember that:

  • Reporters are asked to submit Yellow Card reports even if they only have a suspicion that the vaccine may have caused the adverse reaction. The existence of an adverse reaction report does not necessarily mean that the vaccine has caused the reaction.

  • It may be difficult to tell the difference between something that has occurred naturally and an adverse reaction. Sometimes reactions can be part of the condition being treated rather than being caused by the vaccine.

  • Many factors have to be considered when assessing whether a vaccine has caused a reported adverse reaction. When monitoring the safety of medicines and vaccines, MHRA staff carry out careful analysis of these factors.

  • It is not possible to compare the safety of different vaccines by comparing the numbers presented in the vaccine reports. Reporting rates can be influenced by many factors including the seriousness of the adverse reactions, their ease of recognition and the extent of use of a particular vaccine. Reporting can also be stimulated by promotion and publicity about a product.

For a vaccine to be considered safe, the expected benefits will be greater than the risk of having harmful reactions. It is important to note that most people receive vaccinations without having any serious side effects.

Risks and benefits of medicines

For a medicine to be considered safe, the expected benefits of the medicine will be greater than the risk of suffering harmful reactions. It is important to note that most people take medicines without suffering any serious side effects.

All medicines can cause reactions. The patient information leaflet accompanying the medicine, or available from your pharmacist, lists the known side effects associated with the medicine. Healthcare professionals such as doctors and pharmacists can also provide this information. Information on side effects of medicines can be found on the NHS website.

Monitoring the safety of medicines and vaccines

Information collected through the Yellow Card scheme is an important tool in helping the MHRA and CHM monitor the safety of medicines. Yellow Card reports of suspected adverse reactions are evaluated, together with additional sources of evidence such as worldwide literature, in order to identify previously unidentified hazards or side effects.

If a new side effect is identified, information is carefully considered in context of the overall side effect profile for the medicine or vaccine, and how it compares with other medicines used to treat the same condition.

The MHRA will take action, if necessary, to ensure that the product is used in a way that minimises risk, while maximising patient benefit. Such changes may include, for example, restricting the indication, or special warnings and precautions. Rarely, a drug may need to be withdrawn from the market if the risk of side effects is considered to outweigh the benefits of treatment. Please see our How we monitor the safety of medicines section for further information.

Use of Yellow Card data for publication

If you wish to copy or circulate the information contained within a report to anyone else, please ensure that a copy of these guidelines is also provided.

The MHRA and CHM encourage the use of data from the Yellow Card scheme in research and for publication, but wish to ensure that the limitations of interpretation of the data are made clear.

If you propose to publish information based on Yellow Card data, the MHRA is most willing to provide advice on how the Yellow Card information might be best used and presented. The MHRA is also willing to provide feedback on manuscripts prior to publication. Please write to the Deputy Director, Safety and Surveillance Group by email.