Following the publication of last month's editorial (Tang and Morgan, 2021), the Medicines and Healthcare products Regulatory Agency (MHRA) approved two other COVID-19 vaccines and the Joint Committee on Vaccination and Immunisation (JCVI) amended its recommendations on the dose interval for both Pfizer and AstraZeneca COVID-19 vaccines.
The aim of this article is to address some of the common questions raised by paramedics and other health professionals. This should provide additional information to ensure health professionals have sufficient information about the UK COVID-19 vaccination programme to support their patients to make an informed decision about the vaccine.
UK-approved COVID-19 vaccines
Pfizer/BioNTech, AstraZeneca and Moderna have manufactured three COVID-19 vaccines currently approved by the MHRA for use across the UK.
Both Pfizer/BioNTech and Moderna vaccines are using the new messenger RNA (mRNA) technology by injecting SAR-CoV-2 mRNA (Baden et al, 2020; Walsh et al, 2020). On the other hand, the AstraZeneca vaccine uses the recombinant DNA technology and non-replicating adenovirus cells encoded with the DNA of SARS-CoV-2 Spike glycoprotein are injected into the vaccinated person (Folegati et al, 2020). Both of these would trigger the production of SARS-CoV-2 S antigen in the vaccinated person and the presence of SARS-CoV-2 S antigen in the vaccinated person post vaccination will stimulate the host immune response and induce the production of antibodies against SARS-CoV-2 infection.
Early evaluations demonstrated high efficacy for all three COVID vaccines with Pfizer/BioNTech reporting that their COVID-19 vaccine was 95% effective in preventing COVID-19 (Polack et al, 2020), Moderna reporting 94.1% vaccine efficacy (Baden et al, 2020) and AstraZeneca reporting 62.1% efficacy (Voysey et al, 2021) following the completion of two doses. A comparison of key characteristics of the three COVID-19 vaccines is summarised in Table 1.
Comparison of key characteristics of the three COVID-19 vaccines
|Mechanism of action||mRNA vaccine||Recombinant adenovirus vaccine||mRNA vaccine|
|Population size in the trial (n=)||43 448||23 745||30 420|
|Median follow up period||2 months||3.4 months||2 months (64 days)|
|Location(s) of the trial||United StatesArgentinaBrazilSouth AfricaGermanyTurkey||United KingdomBrazilSouth Africa||United States|
|Manufacturer recommended Dose regimen||Two doses21 days apart||Two doses28 days apart||Two doses28 days apart|
|Vaccine efficacy (full regimen) – reported on||95% (95% CI, 90.3 to 97.6)7 days after 2nd dose||62.1% (95% CI, 41.0 to 75.7)14 days after 2nd dose||94.1% (95% CI, 89.3 to 96.8)14 days after 2nd dose|
|Vaccine efficacy (single dose only) – reported on||52% (95% CI, 29.5 to 68.4)12 days after 1st dose||64.1% (95% CI, 50.5 to 73.9)21 days after 1st dose||95.2% (95% CI, 91.2 to 97.4)14 days after 1st dose|
|Allergies and anaphylaxis||Contains polyethylene glycol/macrogol (PEG) as part of ALC-0159|
|Common side effects||Pain at the injection site (> 80%), fatigue (> 60%), headache (> 50%), myalgia (> 30%), chills (> 30%), arthralgia (> 20%) and pyrexia (> 10%)||Injection site tenderness (>60%) injection site pain, headache, fatigue (>50%); myalgia, malaise (>40%); pyrexia, chills (>30%) and arthralgia, nausea (>20%)||Injection site pain (92%), fatigue (70%), headache (65%), myalgia (62%), arthralgia (46%) chills (46%), nausea/vomiting (23%), axillary swelling/tenderness (19.8%), fever (15.5%), injection site swelling (14.7%) and redness (10%)|
Owing to the fact that all three vaccines are licensed following phase three trial only, there are limited data about the ‘durability’ of the immune response following COVID-19 vaccination at this stage (Widge et al, 2020). It is possible that future booster(s) may be required to ensure immunity is sustained at protective levels. Additionally, although these vaccines have been proven to prevent the development of COVID-19 in the recipients, there is insufficient evidence to determine whether they prevent the transmission of COVID-19 (Peiris et al, 2020). Hence, the use of appropriate personal and protective equipment (PPE) and other guidance should be continued post vaccinations.
Furthermore, as pregnant and breastfeeding women are generally excluded in the early phases of any medicine development trials, this means only limited information is available about the effects of these COVID-19 vaccines in pregnant women. Preliminary animal studies do not indicate direct or indirect harmful effects with respect to pregnancy, embryofetal development, parturition or post-natal development (MHRA, 2020a; 2020b; 2021). Some experts believe that mRNA vaccines are unlikely to pose a risk to the pregnant person or the foetus because mRNA and recombinant vaccines are not live vaccines and the benefits of protection against COVID-19 outweigh the potential risks. The JCVI are recommending vaccination for pregnant women who are at very high risk of catching the virus or those considered clinically vulnerable (Public Health England (PHE), 2021).
The MHRA had initially advised against any person with a history of immediate-onset anaphylaxis to a vaccine, medicine or food receiving the Pfizer BioNTech COVID-19 vaccine (MHRA, 2020c). However, this advice has been updated since and the current only absolute contraindication is those who have had a previous systemic allergic reaction to a previous dose of the same COVID-19 vaccine or any component of the COVID-19 vaccine (Department of Health and Social Care (DHSC), 2020a). It is worth noting that the Pfizer BioNTech COVID-19 vaccine contains polyethylene glycol (PEG). Sellaturay et al (2020) suggested that known allergy to PEG is extremely rare but could lead to serious anaphylaxis. The DHSC (2020a) suggested that caution should be given to those recipients who had a history of unexplained anaphylaxis as they could have an undiagnosed PEG allergy; the AstraZeneca vaccine should be used as an alternative for patients who are known or suspected to have a PEG allergy.
Finally, there is no evidence to support the mixing of different brands of COVID-19 vaccine and the Green Book (DHSC, 2020a: 11) stated that ‘every effort should be made to determine which vaccine the individual received and to complete with the same vaccine…’. PHE has also confirmed that ‘every effort should be made to give the same vaccine, but where this is not possible it is better to give a second dose of another vaccine than not at all.’ (Mahase, 2021).
The UK COVID-19 vaccination programme
The objectives of the COVID-19 vaccination programme is to protect those who are at the highest risk of serious illness or death. The JCVI has set out a prioritisation for persons at risk; this identifies that frontline health and social care workers who provide care to vulnerable people (including paramedics) are among the highest priority groups for the COVID-19 vaccination (DHSC, 2020b).
The JCVI issued new guidance on the dose interval between the first and second dose of the COVID-19 vaccine (DHSC, 2021). Based on the need for a rapid high level of vaccine uptake among the vulnerable group and the high level protection afforded by the first dose, it recommended that the COVID-19 vaccine schedule be changed to an interval of up to 12 weeks from the first dose. The four chief medical officers of the UK suggested that for ‘every 1000 people boosted with a second dose of COVID-19 vaccine (who will as a result gain marginally on protection from severe disease), 1000 new people do not benefit from substantial initial protection which is in most cases likely to raise them from 0% protected to at least 70% protected. These unvaccinated people are far more likely to end up severely ill, hospitalised or in some cases dying without vaccine.’ (DHSC, 2020c). This would enable the prioritisation of the delivery of the first vaccine dose, as this is highly likely to have a greater public health impact in the short term and reduce the number of preventable deaths from COVID-19.
The decision of the changing of vaccination schedule to an interval up to 12 weeks is the balance between early published scientific evidence from vaccine trials and ethical considerations with an aim to optimise the public health impact of the vaccination capacity in the UK.