FAQs about the AstraZeneca vaccine

Not at the moment. Technically it is called ChAdOx1-nCoV19.

It is a vaccine for preventing coronavirus disease (COVID-19) in people over 18 years of age. In Spain, for the time being, it is recommended for administration in people between 18 and 55 years of age.

The vaccine does not contain SARS-CoV-2 and cannot cause COVID-19.

The vaccine is manufactured using another virus (an adenovirus) that has been modified to transport the gene that includes the instructions for producing the S (spike) protein of the virus (the one the virus needs to be able to enter human cells).
 
When a person receives the vaccine, some of their cells read the instructions contained in this gene and produce the S-protein. Their immune system recognises this protein as being foreign, so it produces antibodies and activates T-cells (lymphocytes) to attack it. If the person later comes into contact with the SARS-CoV-2 virus, their immune system will quickly recognise it and initiate a defence response against the coronavirus.
 
The vaccine requires two doses separated by a minimum of 28 days (4 weeks) and a maximum of 84 days (12 weeks).

A clinical trial has been conducted on over 24,000 participants. Half of them received the vaccine (vaccinated group) and half were given a placebo (control group, who in this case received a meningococcal vaccine).
 
Two of these studies, conducted in the United Kingdom and Brazil respectively, were evaluated by the EMA to proceed with the vaccine authorisation. The studies show a 60% reduction in the number of symptomatic cases of COVID-19 in the vaccinated group (64 cases out of 5,258 vaccinated) when compared to the control group (154 cases out of 5,210 unvaccinated).
 
Most of the participants in these studies are aged between 18 and 55 years old. There were not enough participants in the older age groups to provide data on the effectiveness of the AstraZeneca vaccine in those over 55 years of age. However, it is hoped that the vaccine will provide sufficient protection and can be administered to people aged 55 years and above.

21-28 days after the first dose there is already immunity. This reaches peak protection 14-21 days after the second dose.
 
Can people who have already had COVID-19 be vaccinated with the AstraZeneca vaccine?
In the clinical trial, 345 of the participants who received the vaccine had already tested positive for COVID-19. These people were excluded from the effectiveness analysis. No particular or special side effects were recorded among these 345 participants.
 
The current guidelines recommend waiting at least three months from the disease recovery date before vaccinating these people.

In the clinical trial, 345 of the participants who received the vaccine had already tested positive for COVID-19. These people were excluded from the effectiveness analysis. No particular or special side effects were recorded among these 345 participants.

The current guidelines recommend waiting at least three months from the disease recovery date before vaccinating these people.

We still do not know. It is not known what percentage of people who have been vaccinated may still carry the coronavirus and transmit the infection.

We still do not know. All the trial participants will continue to be monitored (for up to 2 years) to provide further information on how long the protection lasts.

Experimental data indicates that immunity to COVID-19 is likely to last for months or years, but not for life.

The AstraZeneca vaccine is not recommended for children under 18 years of age because there is currently no information about the effects on this age group. The EMA has reached an agreement with AstraZeneca to conduct a trial on this population group at a later stage.

The data is still limited. It is possible that immunosuppressed people will not respond as well to the vaccine, but from a safety perspective there are no additional problems.

Immunosuppressed people can be vaccinated, as they have a high risk of developing severe forms of COVID-19.

Studies in animals do not show any adverse effects in pregnancy. However, the vaccines used mostly in pregnancy are those containing messenger ribonucleic acid (mRNA), which are those from Pfizer and Moderna; so these are more recommended during this period.

In the United States, over 100,000 pregnant women have already been vaccinated with mRNA vaccines, and no safety concerns have been identified in either the mother or baby.

Based on the information available to date and accumulated experience, the vaccination of pregnant women is safe. This is especially recommended, given that SARS-CoV-2 infection during pregnancy increases the risk of complications and of developing severe COVID-19 during pregnancy. It can be administered at any time during pregnancy, and women planning a pregnancy can receive any of the COVID vaccines without having to wait between vaccination and conception.

Breastfeeding women can receive the vaccine without having to stop breastfeeding.  Another benefit of vaccinating pregnant and breastfeeding mothers is that the antibodies produced are transferred to the foetus through the breast milk.

Most people who are vaccinated will not experience significant side effects. These may appear during the first week after vaccination. They are not usual after the first two days.
 
The frequent mild or moderate effects observed in clinical trials were (source: EMA):
 
In more than 1 out of 10 people vaccinated:

• Pain and swelling at the injection site.
• Tiredness.
• Headache.
• Muscle and/or joint pain.
• Fever.

In less than 1 out of 10 people vaccinated:

• Nausea and vomiting.
• Diarrhoea.

In less than 1 out of 100 people vaccinated:

• Loss of appetite.
• Sweating.
• Dizziness.
• Abdominal pain.
• Rash.

Painkillers, like paracetamol, can be taken, if necessary, to mitigate these effects.

The AstraZeneca vaccine is contraindicated in people who have had an anaphylactic-type hypersensitivity reaction to a previous dose of COVID-19 vaccine or one of its components.

As with all vaccines, it should always be administered under supervision and with all the medical equipment on hand to deal with a possible immediate serious allergic reaction.