Oxford/ AstraZeneca Vaccine
As of 30th December 2020 the UK Government have accepted the recommendation from the Medicines and Healthcare products Regulatory Agency (MHRA) to authorise Oxford University/AstraZeneca’s Covid-19 vaccine for use. This follows rigorous clinical trials and a thorough analysis of the data by experts at the MHRA, which has concluded that the vaccine has met its strict standards of safety, quality and effectiveness.
Studies suggest that it the Oxford/ AstraZeneca vaccine prevents around 70% of people developing strong Covid-symptoms.
The data also shows a strong immune response in older people, which is very promising as historically vaccines are less successful in older people; this is due to the aged immune system, seen for example, with the annual flu jab.
The vaccine is given in two doses, in the same way as the Pfizer vaccine, but can be stored at fridge temperature which makes it a lot easier to distribute. The vaccine is also cheaper than the others currently available, making it more accessible to a greater number of communities.
How is it made?
The AstraZeneca COVID-19 vaccine is an adenovirus vector vaccine. It is made from a weakened version of a common cold virus from chimpanzees (the adenovirus), which is used as a carrier to deliver the SARS-CoV-2 antigen. The adenovirus has been modified so that it cannot replicate (grow and multiply by making copies of itself) in human cells and therefore cause any disease.
In the human trials for the vaccine more than 99% of the participants had neutralising antibody responses two weeks after the second dose.
Mild pain and tenderness at the injection site are the most common side effects reported following the Oxford/ AstraZeneca COVID-19 vaccine. Short lived symptoms including fatigue and headache were also noted but decreased with age, and were unusual after the second dose.
Mild fever (>38°C) was recorded in the first 48 hours for around a quarter of younger participants, but was not reported in those over 55 years of age or in any age group after the second dose.
Interchangeability of different COVID-19 vaccines
There is no evidence as to the interchangeability of the different COVID-19 vaccines although studies are underway. Public Health England attest that every effort should be made to determine which vaccine the individual received and to complete with the same vaccine. For individuals who started the schedule and who attend for vaccination at a site where the same vaccine is not available, or where the first product received is unknown, it is reasonable to offer a single dose of the locally available product. As both the Pfizer-BioNTech and AstraZeneca vaccines are based on the spike protein of the virus, it is likely that the second dose will help to boost the response to the first dose.