The second dose with Pfizer is effective and safe for those who have received a first dose of AstraZeneca

A study conducted by the Carlos III Health Institute (ISCIII) found that People vaccinated with a first dose of AstraZeneca vaccine will be able to safely and effectively receive a second dose of Pfizer. With a trial carried out on 672 volunteers, the presented report indicates that the response to the combination of drugs is immune and that they have similar side effects.

From the survey called CombivacS Five hospitals in Madrid, Bilbao and Barcelona took part, due to the cancellation of the supply of the AstraZeneca vaccine due to the thrombotic effects linked to the inoculation of the Anglo-Swedish doses on April 7 in Spain.

The study concludes that the side effects of the combination of the vaccines are mild and very similar to those produced with a second dose of AstraZeneca. In turn, they estimated that the protection from a second inoculation with Pfizer could be even greater, since the neutralizing antibodies that protect the body against the coronavirus are four times greater.

📢 Preliminary results of the clinical trial #CombivacS: the combined use of vaccines #AstraZeneca Yes #Pfizer against # SARS-CoV-2 provides a powerful immune response against the virus.

📰 All information #NewsISCIII ➡️ https://t.co/Yf3ngYOwjV pic.twitter.com/Lf7AdeRwSp

– Carlos III Health Institute (ISCIII) (@SaludISCIII) May 18, 2021

The people who participated in the study were subjects who had received the first dose of AstraZeneca vaccine between 8 and 12 weeks previously. The 672 research volunteers were divided into two groups to test the reaction between the 442 who received a second from Pfizer and the 221 who received no other vaccine.

The immune response of the vaccinated group multiplied by 120 in the week after the second dose, while the control maintained the previous level.

“More specifically, the antibody titers according to the technique which identifies the SARS-CoV-2 receptor binding region increased from a median of 58 to a value of 9,102, which represented a 150-fold increase in antibody titers, which was still very evident even 7 days after the booster dose participants received. On the contrary, in the control group, the antibody titers remained at levels similar to those obtained 14 days previously ”, indicates the CombivacS study.

Why most children don’t need the vaccine

Regarding side effects, the combined vaccination with Pfizer obtained results very similar to those seen after the second dose of AstraZeneca. The effect is “mild” and most experience only pain at the stinging site, headaches and general discomfort.

According to the patient’s own assessment, only 2.5% of those vaccinated reported fever, with 68% of mild symptoms; 30% moderate and 1.7% more important. There were no serious or hospitalizations requiring hospitalization.

Increase combination vaccination between AstraZeneca and Pfizer

After the Spanish government decided on April 7 to stop vaccination with AstraZeneca for people under the age of 60 due to the rare and life-threatening thrombi associated with the drug, the Ministry of Health must comment on the implementation of the CombivacS study.

It’s a decision on the group of essential workers (teachers, soldiers, rescuers, police officers, etc.) who have received a dose of AstraZeneca and they ended up without the second because of the effects of the vaccine.

This afternoon there will be a meeting at the Vaccine Conference, which will be attended by a group of independent technicians who advise the ministry. After the meeting, experts will issue a recommendation to the government.

The result of the Combivacs study had international repercussions as it could serve as an approval to mix drugs, while European Medicines Agency (EMA) had previously recommended injecting a second dose of AstraZeneca to those who had received the first.

CI / FL