The EU endorses “mix and match” vaccines against COVID in initial guidelines and in booster doses



The European Union recommends “mix and match” vaccines in initial regimens and in booster doses. Especially if the first or the first two are viral vector vaccines, such as AstraZeneca and Janssen. This has been defended this Tuesday by the European Medicines Agency (EMA) and the European Center for Disease Prevention and Control (ECDC), which explain that an increasing number of clinical studies have examined the possibility of using two COVID-vaccines. 19 different doses, either for the first and second doses of a primary regimen (initial cycle), which is known as heterologous primary vaccination, or using a third dose of a different vaccine for the booster dose between 3 and 6 months after a primary vaccination cycle (heterologous booster).

Thus, the EMA and the ECDC explain that the data on heterologous vaccination “suggest that the combination of viral vector vaccines [tipo AstraZeneca] and mRNA vaccines [tipo Pfizer o Moderna] produces good levels of antibodies against the COVID-19 virus (SARS-CoV-2), as well as a higher T-cell response than using the same vaccine (homologous vaccination) either in the initial regimen or with the dose of reinforcement”.

“In general, the heterologous regimens were well tolerated”, state the EMA and the ECDC, which recalls that “the use of a viral vector vaccine [tipo AstraZeneca] as a second dose in the primary regimen, or the use of two mRNA vaccines [Pfizer y Moderna] different, it is less studied “.

“The data point toward acceptable tolerability and enhanced immune responses with the sequential heterologous vector vaccine regimen [/vacuna de ARNm frente al régimen de vacunación de vector homólogo”, afirman las entidades: “El régimen heterólogo es capaz de inducir un aumento significativo de las respuestas inmunitarias, incluidas las células B de memoria reforzadas, en comparación con un régimen de vector viral homólogo. A veces se observa un ligero aumento en las respuestas inmunes humorales con respecto a la vacunación con ARNm homólogo, pero no de manera consistente, apoyando en general una respuesta de anticuerpos similar”.

Los dos organismos de la UE afirman que mezclar y combinar vacunas “puede ofrecer flexibilidad en caso de que no esté disponible una vacuna por cualquier razón”.

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