Is mixed COVID-19 vaccination Safe, & Effective?
COVID-19 mixed vaccination facts
We have received numerous inquiries regarding COVID-19 mixed vaccination, which requires the candidate to administer two doses of two different vaccines.
AstraZeneca is a two-dose vaccine, with the second dose required to be considered "completely vaccinated."
Being fully vaccinated provides greater protection against COVID-19 illness and new virus variants, such as the Delta variant.
Normally, if you received the AstraZeneca vaccine for the first time, you should receive a second dose of the same vaccine. Numerous studies have been conducted to determine the safety and effectiveness of two doses of this vaccine. (1)
mRNA vaccine following the initial dose of AstraZeneca
Certain individuals have opted out of receiving a second dose of the AstraZeneca vaccine. In extremely rare instances, individuals experienced severe side effects following the first dose of the AstraZeneca vaccine. These individuals have been advised against receiving a second dose of this vaccine. (2)
If you received a first dose of the AstraZeneca vaccine and do not wish to receive a second dose, you may opt for an mRNA COVID-19 vaccine dose (Pfizer/BioNTech). In this case, the individual is also considered "completely vaccinated."
Obtaining two distinct vaccines
After receiving one dose of the AstraZeneca vaccine, you may choose to receive an mRNA vaccine as your second dose. Although this has been approved by Ireland's National Immunization Advisory Committee (NIAC), it has not been approved or licensed by the European Medicines Agency (EMA), which previously approved using only two doses of the same COVID-19 vaccine.
Mixed Oxford/Pfizer vaccine
In a scientific paper published on the Lancet pre-print server, they report that both ‘mixed’ schedules (Pfizer-BioNTech followed by Oxford-AstraZeneca, and Oxford-AstraZeneca followed by Pfizer-BioNTech) induced high concentrations of antibodies (3) , against the SARS-CoV2 spike IgG protein.
Which vaccine to be administered first?
As stated by Prof. Matthew Snape; chief investigator of The Com-COV study, the evaluation followed a “mix and match” combinations approach of the Oxford and Pfizer vaccines to see to what extent these vaccines can be used interchangeably, potentially allowing flexibility in the UK and globally. Therefore, the order of vaccines makes a difference.
Take home messages:
• The coronavirus (COVID-19) vaccines are safe and effective. They give you the best protection against COVID-19.
• If you're pregnant or under 40 you'll usually be offered appointments for the Pfizer/BioNTech or Moderna vaccines.
• If you're under 18, you'll only be offered the Pfizer/BioNTech vaccine.
• You should have the same vaccine for both doses unless you had serious side effects (such as a serious allergic reaction) after your 1st dose.
• In case of severe side effects, you may opt off the first vaccine received as an initial dose, and change it to another type after seeking medical consultation.
• Taking mixed vaccines schedule is not harmful. It provides the protection required to guard against COVID-19 infection, and the order of vaccines makes a difference.
There is currently a lack of data regarding the safety of receiving two different COVID-19 vaccines in comparison to receiving two doses of the same vaccine. However, there have been no reports of serious side effects associated with this option, although some side effects may occur, including pain where the injection was given, headache, muscle aches and possibly chills and fever.
1. The Oxford/AstraZeneca COVID-19 vaccine: what you need to know
2. Mixed Oxford/Pfizer vaccine schedules generate robust immune response against COVID-19
3. https://comcovstudy.org.uk/home when doses were administered four weeks apart.