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(CNN Spanish) – One of the questions from our audience is whether the vaccine against covid-19 can be interchangeable, that is, if different brands of vaccines can be combined. Some scientists have said that it is possible.
Now Canada approved the mixture of vaccines from different brands. Dr. Elmer Huerta explains the details of the investigations and this decision.
You can listen to this episode on Spotify or your favorite podcast platform or read the transcript below.
Hello, I am Dr. Elmer Huerta and this is your daily information on the new coronavirus. Information that we hope will be useful to take care of your health and that of your family.
Today we will see that Canada has just approved the mixing of vaccines of different brands, making it possible for a person who received the first dose of AstraZeneca / Oxford, to complete it with a vaccine from Pfizer / BioNTech if they wish.
Can vaccines be combined?
This decision is, in fact, a potential blow to the prestige and acceptance of the AstraZeneca vaccine, which, as we have heard in previous episodes, had presented some problems with its efficacy and its relationship with the development of blood clots.
A Statement from Canada’s National Advisory Commission on Immunization (NACI) states that in addition to combining the AstraZeneca / Oxford / and Pfizer / BioNTech vaccines, the Pfizer and Moderna vaccines are interchangeable. That is, you can start with one and end with the other and vice versa.
According to the statement, to be considered interchangeable, vaccines must have the same indications and administration intervals, contain similar types of antigens, and be similar in terms of safety, side effects, ability to stimulate the defense system, and similar efficacy to prevent infection. disease.
The document emphasizes that there are currently several vaccines of different types that can be exchanged, citing as examples, vaccines for:
hepatitis A, hepatitis B, influenza, MMR vaccine against measles, mumps, rubella, conjugate vaccines against meningococcus, vaccines against tetanus, whooping cough, poliomyelitis and against Haemophilus influenzae type b.
The studies that support the vaccine mix
The Commission says its decisions on the safety of the vaccine exchange are based on three scientific studies, two of which were described in the May 19 episode.
The British study
The first is the UK CoM-Cov study, published in The Lancet on May 12, studying 463 volunteers over the age of 50 who received various combinations in the order of administration of the AstraZeneca and Pfizer vaccines, some starting with one and ending with the other.
The publication reports that, although the side effects were slightly greater when the second dose was of a different vaccine than the first, none were serious enough to hospitalize the volunteers.
The Spanish study
The second is the Spanish CombiVacS study, in which it was seen that the side effects, documented through an electronic diary, were mild and similar to those reported in studies of the Pfizer vaccine, without requiring extra medical attention or hospitalization in any case.
The German Study
The third is a German observational study of 326 healthcare workers with an average age of 34 years, in which the presence of symptoms after the second dose of a mixed schedule of AstraZeneca and Pfizer / BioNTech vaccines was compared with 12 weeks interval.
The side effects of the vaccine mix
In general, the symptoms of reaction to the vaccines were mild and included:
headache, fever, muscle pain, chills, and joint pain.
There were no serious adverse events or hospitalizations.
Finally, and in relation to the stimulation of the defense system, the Canadian statement says that the Spanish study showed that in people who had received the first dose of the AstraZeneca / Oxford vaccine and completed it with that of Pfizer / BioNTech, antibody titers against virus binding receptors increased approximately 80-fold, anti-spike antibody levels increased approximately 37-fold, and neutralizing antibody titers increased 45-fold.
In summary, as in Denmark, Finland, France, Germany, Norway, Spain and Sweden, in Canada it is possible to start with the AstraZeneca / Oxford vaccine and end with a messenger RNA vaccine, and combine the Moderna vaccines in any order. and Pfizer, a trend that we are sure will spread to other countries around the world in the coming months.
Do you have questions about the coronavirus?
Send me your questions on Twitter, we will try to answer them in our next episodes. You can find me at @DrHuerta.
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