Oxford / AstraZeneca COVID-19 vaccine – frequently asked questions
What is the efficacy of the Oxford / AstraZeneca COVID-19 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%).
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.
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.
Is the vaccine safe in pregnancy and breastfeeding?
Pregnancy: There is a limited experience with the use of COVID-19 Vaccine AstraZeneca 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; definitive animal studies have not been completed yet.
The full relevance of animal studies to human risk with vaccines for COVID-19 remains to be established. Administration of COVID-19 Vaccine AstraZeneca in pregnancy should only be considered when the potential benefits outweigh any potential risks for the mother and fetus.
Breastfeeding: There is evidence from some vaccines that the breast-feeding baby may acquire a level of protection. The vaccine is recommended for use during breast feeding.
Fertility: Preliminary animal studies do not indicate direct or indirect harmful effects with respect to fertility.
How was the vaccine developed so quickly?
Medicines, including vaccines, are highly regulated – and that is no different for the approved COVID-19 vaccine.
There are a number of enablers that have made this groundbreaking medical advancement possible and made it possible to develop them relatively quickly compared to other medicines.
- The different phases of the clinical trial were delivered to overlap instead of running sequentially which sped up the clinical process.
- There was a rolling assessment of data packages as soon as they were available so experts at the MHRA could review as the trial was being delivered, ask questions along the way and request extra information as needed – as opposed to getting all information at the end of a trial.
- Clinical trials managed to recruit people very quickly as a global effort meant thousands of people were willing to volunteer.
Are the vaccines effective against new strains of the SARS COV-2 virus?
It is possible that the vaccine has reduced efficacy against some of the new strains, but very likely even for those strains that the recipient will be protected from severe disease. While further work is ongoing in this field, the advice is to continue with the vaccination as planned
Do I need to continue to social distance and wear a face covering after receiving the vaccine?
It is important to note that even when you have received both doses of the vaccine, you must continue to follow current guidance on social distancing and wearing a face covering when you are in public places. You must also to continue to follow the current PPE use guidance when you are at work and out in the community.
If I’ve had a positive antibody test, should I still get vaccinated?
Yes, it is currently recommended that the vaccine can and should be given if you have had a positive antibody test.
I’m currently ill with COVID-19, can I get the vaccine?
People currently unwell and experiencing COVID-19 symptoms should not receive the COVID-19 vaccine until they have recovered.
Should I get vaccinated if I have already had COVID-19?
Yes, you should get vaccinated against COVID-19 even if you have already had the disease. However, if you are currently infected, you must wait for your symptoms to resolve, your isolation period to end and if you were prescribed steroids, these must also have ended. This applies to either of the doses of the COVID-19 vaccine.
What if I missed the second dose?
If the vaccine you received recommends two doses and you miss the second dose, it is best that you take it within seven (7) days of the missed date. However, if for some reason the second dose is delayed further, you shouLd get the second dose as soon as possible.
How long should I wait to get any other vaccine, after getting the COVID-19 vaccine?
After getting vaccinated for COVID-19, you must wait 14 days, before getting any other type of vaccine, for any other disease or condition.
How do I access the vaccine?
The vaccine is on offer at the Aga khan University Hospital Nairobi, as well as other designated centers. Please liaise wish your supervisor to schedule you for vaccination. The AKUH, N vaccination center is at the Jamat Khan Pavillion (the usual venue for convocations) near the Mosque. The center is open from 7:30 a.m. to 4:30 p.m. on weekdays.
Do I require to continue taking infection prevention precautions after vaccination?
Yes, you require to continue with the usual precautions of wearing face masks, physical distancing, cough etiquette, use of PPEs and hand hygiene.
This article is from the Aga Khan University Hospital website
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