Oxford/AstraZeneca Covid-19 Vaccine - Frequently Asked Questions
Is it mandatory to get vaccinated against COVID-19?
The COVID-19 vaccine is not mandatory. However, considering the benefits of vaccination against severe disease and death, it is strongly recommended that all eligible persons be vaccinated. The need for vaccination is even greater for healthcare workers.
What is the efficacy of the Oxford / AstraZeneca vaccine?
In the different clinical trials conducted, this vaccine has been shown to protect against symptomatic infections with an efficacy ranging between 60% and 90%. According to an analysis published in The Lancet, this difference may be due to the interval between both doses: a longer interval (12 weeks) protects better (above 80%) than an interval below 6 weeks (under 60%).
To date, no hospitalizations or deaths have been registered among people who received both doses of the Oxford / AstraZeneca vaccine in clinical trials.
Does the Oxford / AstraZeneca vaccine protect against the new viral variants?
According to preliminary results obtained in the UK, this vaccine maintains a high efficacy against the “British" (B1.1.7) variant. In contrast, its capacity to protect against symptomatic infections caused by the variant first identified in South Africa (B1.351) seems to be much lower (around 25%) according to a small clinical trial in the African country. Still, it is hoped that it will protect against hospitalisation and death, since to date no cases of hospitalisation or death by COVID-19 have been reported in people who have received both doses of the vaccine in clinical trials. Even in South Africa, the vaccine prevented severe disease.
How long does it take to be protected by the Oxford / AstraZeneca vaccine?
Preliminary results from Scotland show that the Oxford / AstraZeneca vaccine drastically reduced COVID-19 hospitalizations (by 94%) one month after the first dose, even in persons above 80 years of age. However, this does not mean one dose is enough since it is not clear how long the protection would last after one single dose.
Why is the Oxford / AstraZeneca vaccine not given to older people in some countries?
The European Medicines Agency approved the Oxford/AstraZeneca vaccine for use in all ages from 18 years onwards. However, some European countries (including Spain) have decided not to use the vaccine in people above 55 years of age because the clinical trials did not include enough people in this age group in order to draw firm conclusions. Nevertheless, the United Kingdom is using this vaccine even in people above 80 years of age, and the first data from Scotland show that it works well in the elderly: four weeks after the first dose, a 90% decrease in hospitalizations is observed.
What are the contra-indications to the administration of the vaccine?
Hypersensitivity to the active substance or to any of the excipients. Note that none of the currently available vaccines include human or animal products. Thus, egg allergy is NOT a contraindication.
A positive IgG test (i.e., having been exposed to the disease) is not an exclusion criterion for vaccination; available data suggest that previously infected individuals can be at risk of COVID-19 reinfection and could benefit from vaccination.
The administration of COVID-19 vaccines should be postponed in individuals suffering from acute severe febrile illness.
Individuals with bleeding disorders may receive a COVID-19 vaccine if considered safe to do so by a physician familiar with the individual's bleeding risk.
What are the side effects of the vaccine?
Injection site tenderness (>60%); injection site pain, headache, fatigue (>50%); myalgia, malaise (>40%); pyrexia, chills (>30%); and arthralgia, nausea (>20%). The majority of adverse reactions were mild to moderate in severity and usually resolved within one to two days of vaccination. By day 7 the incidence of subjects with at least one local or systemic reaction was 4% and 13%, respectively. When compared with the first dose, adverse reactions reported after the second dose were milder and reported less frequently.
How do I obtain help if I got side effects?
Within 15 minutes of vaccination, there is a doctor to provide care at the vaccination center. Beyond 15 minutes (and after leaving the vaccination center) please obtain care at the Accident and Emergency department.
How does the vaccine work?
Viral vector-based vaccines use the body's own cells to produce antigens. They do this by using a modified virus (the vector) to deliver the genetic code for the antigen, which then triggers an immune response. The vaccine mimics what happens during natural infection with certain pathogens — especially viruses. This has the advantage of triggering a strong cellular immune response by T cells as well as the production of antibodies by B cells.
How many doses should one take?
Two doses 4-12 weeks apart are administered. In Kenya, the doses shall be 8 weeks apart.
What is the duration of protection after vaccination?
The duration of protection has not yet been established. As with any vaccine, vaccination with COVID-19 Vaccine AstraZeneca may not protect all vaccine recipients.