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Effectiveness and safety profile of COVID-19 vaccine-evidence so far

Updated on 2.1.2021

Given that some of our patients may be soon called and invited to have a Covid-19 vaccine Dr Beanland has prepared the following information below for you to read and inform yourselves about the vaccines available. There is more information on our website and the link is given at the end of this post.
We know some of you are worried about the vaccine and need some reassurance so we have tried to do our best by providing extensive information on our website. As more information comes in we will endeavour to update you.

Licenced and approved Covid-19 vaccines

The MHRA has already approved the Pfizer vaccine and licenced in the UK.

The Oxford/ Astra-Zeneca vaccine has been approved in the UK on 30/12/2020.

Who should not have the vaccine?

  • Not currently recommended for anyone under the age of 16.
  • Not currently recommended for anyone who is pregnant,  who thinks they may be pregnant, who is planning to get pregnant or who is currently breastfeeding

This is not due to data indicating a safety concern, but insufficient evidence to routinely recommend use. With this in mind, women do not routinely need to be asked about LMP and pregnancy testing prior to vaccination is not required. Termination should not be recommended after inadvertent vaccination during pregnancy, but these cases should be reported and followed up by the Public Health Immunisation Department.

  • Cannot be given to anyone who has had a confirmed anaphylactic reaction to any component of the vaccine or residues from the manufacturing process.
  • Anyone who has had a previous severe anaphylactic reaction to a vaccine, medicine or food.

People should not be vaccinated with this vaccine if they have a history of allergic reactions severe enough to require them to use an EpiPen (Adrenalin) to inject when they get a severe allergic reaction following updated advice from the MHRA.

1. Any person with a history of a significant allergic reaction to a vaccine, medicine or food (such as previous history of anaphylactoid reaction or those who have been advised to carry an adrenaline autoinjector) should not receive the Pfizer BioNtech vaccine.

2. Resuscitation facilities should be available at all times for all vaccinations. Vaccination should only be carried out in facilities where resuscitation measures are available.

  • Cannot be given to anyone currently suffering from an acute severe febrile illness (the presence of a minor infection is not a contraindication for vaccination)
  • Cannot be given to anyone who has had confirmed COVID-19 infection in the preceding 4 weeks
  • Cannot be given to anyone for whom no valid consent has been obtained (for more information about consent please follow the link below)

Link to consent forms (currently in construction)

Frequently asked or possible questions published by NB Medical (5)

See link below for answers to common questions

Frequently asked Questions and Answers about the Covid Vaccine

The importance of vaccines-introduction

Vaccines have contributed enormously in reducing the impact of many infectious diseases, and the expanded use of new and existing vaccines provides unprecedented potential for further reducing the global burden of infectious diseases. It is the most effective method of controlling seasonal influenza infections and the most important strategy for preventing pandemic events.

Different vaccines are recommended for children, adults, pregnant women and elderly patients or all these groups and have to meet higher safety standards, since they are administered to healthy subjects, mainly healthy children. Although vaccines are strictly monitored before authorization, the possibility of adverse events and/or rare adverse events cannot be totally eliminated.

The safety of vaccines is a critical factor in maintaining public trust in national vaccination programs.

How is vaccine safety evaluated?

In initial phases, studies are carried out in the lab and on animal models.  These phases usually take many years.

Phase 0 trials usually are carried out using tiny doses (microdoses) of the drug to obtain basic information about how the drug is broken down by the body usually on 1-2 individuals.

Phase 1 trials are designed to assess the safety, and tolerability of the medication usually on 20-25 healthy volunteers. These trials usually last 6-12 months.

Phase 2 trials are further exploratory trials of 20-300 Subjects to confirm the effectiveness, monitor side effects, & further evaluate safety. These trials usually take 6 months to many years.

Phase 3 trials usually confirm whether or not a vaccine is effective and prevents the target disease e.g. Covid-19. Usually consists of several 100’s to 3000 patients. The usual duration is a few years to up to 5 years. These trials establish the efficacy of the vaccine (how successful it is at preventing disease)  and to collect further safety data.

Following the phase 3 trials an application is made for the vaccine to be icenced for use on humans by the appropiate medical body.

In the UK the body that evaluates the evidence is the MHRA. The MHRA is a centre of the Medicines and Healthcare products Regulatory Agency  The MHRA is an executive agency of the Department of Health and Social Care. It is responsible for regulating all medicines and medical devices in the UK by ensuring they work and are acceptably safe. All our work is underpinned by robust and fact-based judgements to ensure that the benefits justify any risks.

What are the current studies ongoing for Covid-19 vaccines and what stage of trials are they currently on?

A summary of current trials and stages are found in a paper published in November 2020 by the Lancet (1). The trials that in phase 3 and their location are shown below:


Evaluation of different vaccines so far

Pfizer/Biotech vaccine

The MHRA Committee has reviewed unpublished Phase I/II/III safety and efficacy data for the Pfizer BioNTech mRNA vaccine. (2)

The phase III trial began on 27 July and enrolled 43 661 participants. Around 42% of global participants and 30% of US participants had “racially and ethnically diverse backgrounds,” while 41% of global and 45% of US participants were aged 56 to 85 years. Pfizer has said efficacy was consistent across age, sex, race, and ethnicity demographics, with 94% efficacy in adults aged over 65 years.

Published results are now available at the New England Journal of Medicine (6) Dec 31st 2020.

Regarding dose intervals for Pfizer vaccine

Pfizer has said it has tested its vaccine’s efficacy only when the two vaccines were given up to 21 days apart. However on closer look at the analysis of their data which has been published in the New England Journal of Medicine (NEJM) on 31st December 2020, they also analysed the cases of Covid-19 in a subgroup of patients who tested positive for Covid-19 in between the first dose and the second dose, these were 39 cases in the BNT162b2 group and 82 cases in the placebo group were observed, and therefore we can suppose that the vaccine efficacy of at least one dose of the vaccine was 52% (95% CI, 29.5 to 68.4) during this interval and indicating early protection by the vaccine, starting as soon as 12 days after the first dose. (1)

Submissions have been sent to regulatory bodies and have included solicited safety data from a randomised subset of around 8000 participants aged 18 or over and unsolicited safety data from around 38 000 trial participants who were followed for a median of two months after the second vaccine dose.

The trial’s data monitoring committee has not reported any serious safety concerns related to the vaccine. Common side effects are as follows:

►Injection site pain >80% (usually not red/swollen)

►Fatigue >60%

►Headache >50%

►Fever with myalgia, arthralgia & chills 10-20%

►Lymphadenopathy <1%.

►Adverse effects severe enough to interfere with daily activity includes fatigue 4% and headache 2%.

Updated evidence on 10th December following two NHS workers having experienced ‘anaphylactoid reactions’ after receiving doses of the Pfizer/BioNTech vaccine on the 9th December, according to case reports sent to the MHRA.

Astra-Zeneca/Oxford vaccine

University of Oxford covid-19 vaccine team have reported and published their phase II trial results in the Lancet (3), concluding that the vaccine candidate (ChAdOx1 nCoV-19) produced a similar immune response in old and young adults.

The phase 2 trial, carried out between May 30 and August 8. The safety data published so far is from over 20,000 participants enrolled across four clinical trials in the UK, Brazil and, in addition, from South Africa. The Lancet publication confirmed that AZD1222 was well tolerated and that there were no serious safety events confirmed related to the vaccine. The participants were from diverse racial and geographic groups who are healthy or have stable underlying medical conditions. This analysis provides safety data on 74,341 person-months of follow-up after first dose (median 3.4 months) and 29,060 person-months of follow-up after two doses (median 2.0). The overall reported rates of serious adverse events were 0.7% in the vaccine group and 0.8% in the control group.

They have also reported and published interim phase 3 trial data in the Lancet on 8th December 2020. (4) Fully published data should be available in the next few weeks.

The interim analysis for efficacy was based on 11,636 participants accruing 131 symptomatic infections from the Phase III UK and Brazil trials conducted by Oxford University.

As announced on 23 November 2020, the data showed that the vaccine is 70.4% effective at preventing symptomatic COVID-19 occurring more than 14 days after receiving two doses of the vaccine. A secondary data set demonstrated no cases of severe infections or hospitalisations in the vaccine group. A further analysis of the effectiveness showed that when the vaccine was given as two full doses, vaccine efficacy was 62.1%, and 90.0% in participants who received a half dose followed by a full dose.

There were no hospitalisations or severe cases of COVID-19 more than 21 days after the first dose of the vaccine. More data will continue to accumulate as part of the upcoming primary analysis and further follow-up, refining the efficacy reading and characterising vaccine efficacy over a longer period of time.

Regarding dose intervals for the Astra-Zeneca vaccine.

Regarding the Astra-Zeneca/Oxford vaccine the was variability in the interval between doses as part of the trial, some trials initially were based on only one dose of the vaccine and others were based on two. The timing of the first and second booster vaccine varied between studies. As protocol were changed and owing to the time taken to manufacture and release a new batch of vaccine, doses could not be administered at a 4-week interval for all groups.

The 18–55-year-old groups were originally planned as single-dose efficacy groups. However, the protocol was modified on July 20, 2020, to offer a second dose to these participants. Boosting for these younger age groups began on Aug 3, 2020, resulting in a longer gap between the first and second booster vaccines in these younger groups of between 4 to 12 weeks interval. In the older groups ( those aged 55–69 years and those aged 70 years or older) on the other hand these participants were enrolled into two-dose groups from the start and had their two vaccines 4 weeks apart.

In the groups in the UK and Brazil, vaccine efficacy was similar, at 53·4% in participants with less than 6 weeks’ interval between doses and 65·4% in participants with at least 6 weeks’ interval. So interestingly the evidence for the Astra-Zeneca vaccine is that if your allow a longer interval between the two dosages the vaccine is more effective. However this data is only valid for the younger age groups (18-55 groups) as the older groups were all given the second dose at 4 weeks without variability in the interval.

We do not have data to give a definitive answer about the effect of a delay in your second dose. However, experience from other vaccines tells us that even with a delay, after the booster doses people will usually still develop good immunity.The decision to increase the intervals between doses, not only for the Oxford/AstraZeneca vaccine, but also the BioNTech/Pfizer version, is aimed at protecting more people, more quickly. With no need to keep back half the supply to give second doses to those who have already received a measure of protection, all the available doses can be used immediately.

The trial’s data monitoring committee has not reported any serious safety concerns related to the vaccine. These reactions were less common in older adults (aged ≥56 years) than younger adults.

Adverse side effects are as follows:

►Injection site pain 61-88%

►Fatigue & headache 65-86% – short-lived, mild to moderate, unusual after 2nd dose

►Mild fever in 48h after 1st dose ~25% <55yo, 0%>55yo; none after 2nd dose

Phase 3 trial results are due to be reported

Other vaccines will be added as they are approved or published.


  1. https://www.thelancet.com/action/showPdf?pii=S0140-6736%2820%2932137-1
  2. Pfizer and BioNTech announce vaccine candidate against COVID-19 achieved success in first interim analysis from phase 3 study. Nov 9, 2020. https://www.pfizer.com/news/press-release/ press-release-detail/pfizer-and-biontech-announce-vaccinecandidate-against (accessed Nov 15, 2020)
  3. Ramasay MN, Minassian AM, Ewer KJ et al. Safety and immunogenicity of ChAdOx1 nCoV-19 vaccine administered in a prime-boost regimen in young and old adults (COV002): a single-blind, randomised, controlled, phase 2/3 trial. Lancet2020. thelancet.com/journals/lancet/article/PIIS0140-6736(20)32466-1/fulltextdoi:10.1016/S0140-6736(20)32466-1
  4. Safety and efficacy of the ChAdOx1 nCoV-19 vaccine (AZD1222) against SARS-CoV-2: an interim analysis of four randomised controlled trials in Brazil, South Africa, and the UK Voysey et al December 08, 2020. https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(20)32661-1/fulltext
  5. https://www.nbmedical.com/kiss/kiss-covid-vaccinations?utm_medium=email&utm_campaign=Keep%20It%20Simple%20Summary%20on%20COVID%20Vaccination&utm_content=Keep%20It%20Simple%20Summary%20on%20COVID%20Vaccination%20CID_5f3fce82b4a308b13c04467b1c3d7c0b&utm_source=Email%20marketing%20software&utm_term=Keep%20it%20Simple%20Summaries%20-%20COVID%20Vaccination
  6. https://www.nejm.org/doi/full/10.1056/NEJMoa2034577?query=featured_home


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