With the arrival of more doses of vaccine from Pfizer and BioNTech laboratories in Brazil, also increase the questions about the immunizing agent. See below a question-answer with the main questions about the drug.

1. What is the origin of the immunizing agent?

This drug is the result of a partnership between the laboratories of the North American company Pfizer and the German BioNTech.


2. How is the vaccine made?

This medicine uses only a synthetic part of the genetic material of the SARS-CoV-2 virus, not the virus itself. Therefore, it does not cause the disease Covid-19 on whoever receives it.

The idea is that the part used, a messenger RNA (mRNA), gives the body instructions for the production of proteins (antigens) found on the surface of the virus. Now, the immune system starts to produce Antibodies and defense cells.

Thus, if the person has contact with the disease, the body has the ability to fight the virus without getting sick.

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3. In how many doses is this vaccine applied?

There are two doses, with an interval of greater than or equal to 21 days. Preferably closer to 3 weeks. After the second application, it is important to wait at least 7 days to be protected.

According to Pfizer, it is with this interval of 21 days that the 95% effectiveness in laboratory tests was verified. However, this does not necessarily mean that the longer range detracts from the overall effectiveness.

After all, opinion the UK Joint Committee on Vaccination and Immunization stated that the second dose is expected "to be as effective or more effective when given within 12 weeks of the first dose".

But then, why in Brazil do we vaccinate with a longer interval? The strategy of Ministry of Health it's just giving the first dose to as many people as possible. And, with that, reduce hospitalizations and transmission of the virus.

4. How effective is the drug?

A efficiency of Pfizer and BioNTech's vaccine against Covid-19 is 95%, according to the results of the phase 3 studies. To reach this conclusion, two doses were applied, in an interval of 21 days between them, in more than 44 a thousand volunteers.

In young people aged 12 to 15 years, the vaccine has shown 100% effectiveness in phase 3 studies with 2.260 US adolescents. In view of this favorable result, the National Health Surveillance Agency (Anvisa) approved, in June, the use of immunizing agents in this age group.

Also, the vaccine is safe for pregnant women. It is worth remembering that, in Brazil, only drugs from Pfizer and BioNTech and CoronaVac, produced by Butantan, are authorized for them. The application of the immunizing agent from AstraZeneca and Fiocruz was prohibited in pregnant women by Anvisa.

One in five pregnant/puerperal women killed by Covid-19 did not have access to the ICU
Image: Shutterstock

5. What are the side effects of the Pfizer and BioNTech vaccine?

According to bubble of the immunizing agent, the reactions are divided between:

Common (10% of patients):

  • Pain and swelling at the injection site
  • Tiredness
  • Headache
  • Diarrhoea
  • Muscle pain
  • Joint pain
  • Chills
  • Fever

Most common (between 1% and 10% of patients):

  • Redness at the injection site
  • Nausea
  • Vomiting

Uncommon (between 0,1% and 1% of patients):

  • Enlarged lymph nodes (or tongues)
  • Hypersensitivity reactions, such as skin lesions, itching, tiredness, decreased appetite, among others.

Rare (between 0,01% and 0,1% of patients):

  • acute facial paralysis

6. Do we already have this immunizing agent in Brazil?

In February 2021, Anvisa granted definitive registration to the immunizing agent. With this, two agreements were signed between the laboratories and the Federal Government, in March and in May, for the delivery of 200 million vaccines by the end of the year. The first batch was delivered on April 29th.

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