COVID-19: Vaccines

Information on COVID-19 vaccines in the UK COVID-19: Vaccines

COVID-19 vaccines are being developed worldwide. All must be assessed as effective and meet strict safety standards before being used. In the UK, the Medicines and Healthcare products Regulatory Agency (MHRA), an independent authority, assess the safety, quality, and effectiveness of medicines.

UK Government guidance on the UK groups that must be prioritised for COVID-19 vaccine can be found here: Priority groups for coronavirus (COVID-19) vaccination: advice from the Joint Committee on Vaccination and Immunisation (JCVI)

International travellers have not been identified as a priority group for COVID-19 vaccination, but would be eligible for the vaccine if in priority groups.

Most vaccines being developed use the spike (S)-protein on the virus surface as the target for antibodies that develop when the vaccine is administered to block the virus entering the cells and therefore expected to be protective against COVID-19 infection.

COVID-19 vaccines

Most vaccines being developed use the spike (S)-protein on the virus surface as the target for antibodies that develop when the vaccine is administered to block the virus entering the cells and therefore expected to be protective against COVID-19 infection.

Pfizer BioNTech COVID-19 vaccine

This vaccine is a nucleoside- modified messenger RNA vaccine (mRNA). The genetic code (mRNA) from the SARS-CoV2 virus is used in the vaccine to enter cells of the person vaccinated to make the target S-protein stimulating the antibody response blocking viral entry into cells.

There is currently no evidence to suggest that this vaccine would not protect people against the new variant virus currently circulating in the UK [1].

AstraZeneca COVID-19 vaccine

This vaccine uses a virus that does not cause illness, called a chimpanzee adenovirus (ChAD) to carry the genetic sequence of the SARS-COV S-protein into the cell of the person vaccinated to stimulate the antibody against the S-protein of the virus.

COVID-19 Vaccine Moderna

This vaccine is a nucleoside- modified messenger RNA vaccine (mRNA). The genetic code (mRNA) from the SARS-CoV2 virus is used in the vaccine to enter cells of the person vaccinated to make the target S-protein stimulating the antibody response blocking viral entry into cells.

The vaccines are MHRA authorised and considered inactivated (including the non-replicating adenovirus vaccine) [2].

Vaccine Schedule Age and vaccine effectiveness Duration of protection
Pfizer BioNTech COVID-19 vaccine (mRNA vaccine) Two intramuscular doses of 0.3mls at a minimum interval of 21 days Phase 3 trials: 95% vaccine efficacy across age, gender and ethnicity

Adults over 65 years observed efficacy 94%
Booster doses are not recommended until further vaccine trial studies have been completed
AstraZeneca COVID-19 vaccine
(ChAD)
Two intramuscular doses of 0.5mls at a minimum interval of 28 days Initial efficacy data suggests a 73% efficacy overall

Higher efficacy noted in those given a first dose of 0.25mls followed by a 0.5mls dose
Booster doses are not recommended until further vaccine trial studies have been completed
COVID-19 Vaccine Moderna Two intramuscular doses of 0.5mls at an interval of 28 days Adults aged 18 years and older

Initial data suggests a 94% efficacy
Duration of protection is unknown at present
Note these vaccines are supplied in multidose vials

The second dose of vaccine (preferably using the same vaccine used for the first dose) should still be administered even if an interval longer than the recommended. If the same vaccine is not available as given on the first occasion, it is considered reasonable to give the vaccine available particularly if at immediate high risk of COVID-19 infection or considered unlikely to attend for vaccination again [2].

It is recommended that the second dose of both vaccines should be routinely scheduled between four and 12 weeks after the first dose. This will allow more people to benefit from the protection provided from the first dose during the roll out phase. Longer-term protection will then be provided by the second dose [2].

Based on current information about these COVID-19 vaccines, there should ideally be an interval of at least seven days with other vaccines to avoid incorrect attribution of potential adverse events.

More information about the use of COVID-19 vaccines for those with special health needs including during pregnancy, breastfeeding and those who are immunosuppressed or have HIV infection is available here.

Contraindications and Precautions to COVID-19 vaccination

There are very few individuals who cannot receive the Pfizer-BioNTech, AstraZeneca or Moderna COVID-19 vaccines.

Contraindications:

Confirmed previous systemic allergic reaction (including immediate-onset anaphylaxis) to

  • a previous dose of the same COVID-19 vaccine* [see also Adverse Reactions]
  • any components of the vaccine**
*People who have a systemic allergic reaction to Pfizer-BioNTech vaccine should not be given a dose of the Moderna vaccine, and vice versa [2].

**People with unexplained anaphylaxis or anaphylaxis to multiple classes of medications may be allergic to polyethylene glycol (PEG) a component of some medicines, household goods and cosmetics should discuss with their healthcare provider before receiving the vaccine. PEG is present in the Pfizer-BioNTech and Moderna vaccines [2].

The MHRA has advised that individuals with a history of anaphylaxis to food, an identified drug or vaccine, or an insect sting can receive any COVID-19 vaccine, as long as they are not known to be allergic to any component (excipient) of the vaccine [2].

The British Society for Allergy and Clinical Immunology (BSACI) has advised that:

  • individuals with a history of immediate onset-anaphylaxis to multiple classes of drugs or an unexplained anaphylaxis should not be vaccinated with the Pfizer BioNTech vaccine. The AstraZeneca vaccine can be used as an alternative (if not otherwise contraindicated).
  • individuals with localised urticarial (itchy) skin reaction (without systemic symptoms) to the first dose of a COVID-19 vaccine should receive the second dose of vaccine with prolonged observation (30 minutes) in a setting with full resuscitation facilities (e.g. a hospital).
  • individuals with non-allergic reactions to the first dose of a COVID-19 vaccine can proceed with the second dose in any vaccination setting [2].

Precautions:

If acutely unwell, postpone until fully recovered.

Vaccination of those who maybe infected, asymptomatic or incubating COVID-19 infection should be delayed until clinical recovery and at least 4 weeks after symptoms onset or 4 weeks after a first PCR positive specimen in those who do not have symptoms.

No safety concerns have been noted from vaccinating those with past COVID-19 infection or detectable COVID-19 antibodies.

Having prolonged COVID-19 symptoms is not a contraindication to receiving COVID-19 vaccine, but if there is evidence of current deterioration, deferral of vaccination may be considered.

Adverse Reactions

There were two reports of anaphylaxis and one report of a possible allergic reaction following immunisation at the start of the UK COVID-19 vaccination programme. As a result, the MHRA updated guidance on the management of allergic reactions following COVID-19 vaccination with the Pfizer/BioNTech vaccine.

Mild, local reactions at the injection site are common and other symptoms including fatigue and headache are reported.

Following COVID-19 vaccination, a mild fever, which usually resolves within 48 hours, is a common, expected reaction and isolation is not required unless COVID-19 is suspected.

Detailed information about the use of the vaccine in other groups: pregnancy, breast feeding, children, immunosuppression and HIV is available in Immunisation against infectious disease Chapter 14a.

As these vaccines are labelled with a black triangle, all adverse reactions occurring in individuals of any age after vaccination should be reported to the MHRA using the Yellow Card Scheme.

Resources

First Published :   08 Dec 2020
Last Updated :   25 Jan 2021

COVID-19: Resources

Current coronavirus advice from NaTHNaC, PHE and FCDO, with links to international information sources Read more

Country specific information - Rationale

Epidemiological rationale for recommendations Read more

COVID-19: Testing for international travel purposes

Information on COVID-19 testing before or following travel Read more

Risk assessment / Risk management checklist

This example form shows the type of detail required to inform risk assessment Read more
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