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.  The MHRA has changed the format and frequency of reporting several times.

Due to the limitations of the data, we 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.

In January 2023, the MHRA revised the format of the Summary of Yellow Card reporting, to focus on the COVID-19 vaccines administered from the beginning of the Autumn 2022 booster campaign. Previous and known information on these vaccines will remain available as a record only and can be viewed here.


A new report has been released which covers the period from 22 February to 25 October 2023 (8 months). This report no longer tells us the total number of vaccinations administered since the beginning of the rollout in Dec 2020. Therefore our vaccine related charts below use data to February 2023.

Of interest in the latest report is that since February 2023 there have been 425 new types of reaction (new ailments) reported including:

  • 1922 Brain fog
  • 90 Lactation insufficiency
  • 63 Graves disease (a thyroid autoimmune disease)
  • 34 Dilated cardio-myopathy (including 1 fatality)
  • 5 Abnormal menstrual clots
  • 3 Glioblastoma multiforme (fast growing brain tumor)
  • 3 Lymphomatoid papulosis (a rare form of T-cell lymphoma characterised by crops of recurrent self-healing papules)

Also of note is that for several classes of fatality, the totals reported as at October are lower than those reported in the previous report. These reductions add up to 565, however it is not known whether the reductions are because of reclassification or clerical error. This is not the first time we have encountered this phenomenon and there has been no explanation provided by MHRA.

What We Do Know

What We Don't Know

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.

Yellow Card Summary to 25th October 2023

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 = 20,362

* vaccine dose totals are to February 2023 only

New deaths this report = 136

Data Source: 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

* vaccine dose totals are to February 2023 only


Adverse Reactions


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

Further Research & Resources

MHRA Resources

The MHRA now provides interactive charts to allow the public to explore the Yellow card data in more depth for themselves. Unfortunately the MHRA persists in siloing each vaccine variation (brand/type) into its own dataset so exploring consolidated data or comparing brands remains a challenge. Not all variations have the same reporting options available either.

Here is an overview of the information available from each of the menu options provided for each vaccine.

wdt_ID Menu Option Information Available
1 Information Brand Names, Data Extraction Date, Link to Safety Assessment Documents
2 Overview Summary Data - Total Reports, Reactions etc, Links to Death Registrations for each country
3 COVID-19 Vaccinations (not available for all vaccines) Weekly figures for doses administered & adverse reaction reports made - available as a chart or a table of numbers.
4 Report Profile Interactive charts for demographic information (gender, age etc) - use the settings on the left of the screen to filter the data used to build the charts
5 Reaction Profile Interactive charts for types of reactions (by System Organ Class) - use the settings on the left of the screen to filter the data used to build the charts

Here are links to each of the vaccines variations’ reporting page.

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.