Third Dose of COVID-19 Vaccine: What Science Says About Its Importance

This Friday began the application of the third dose against COVID-19 for all front-line health personnel. Immunization will be carried out with the vaccine from the pharmaceutical company Pfizer in all the hospitals of the Ministry of Health and EsSalud.

Given the evidence that the protection provided by vaccines decreases to a certain extent over the months and in the face of new variants of the coronavirus, various governments decided to apply an additional dose, either from the same brand or from another. But

Along the same lines as the US Food and Drug Administration (FDA), the World Health Organization (WHO) advisory group of vaccine experts recommended last week that anticovid, despite the fact that the agency had asked in August for a moratorium on these booster inoculations.

Mexican Alejandro Cravioto, president of the WHO Strategic Advisory Group of Experts (SAGE), made this announcement after the meeting held at the beginning of October by this body, in which vaccination strategies against COVID-19 and other vaccination strategies were analyzed. diseases, such as malaria or polio.

The experts also recommended that the international community look to mid-2022.

“It is a much higher percentage than we thought before, but given the development of the pandemic and the availability of new vaccines for younger age groups, it is a possible target”, stressed the president of SAGE.

Regarding the third dose (or second in the case of the Johnson & Johnson single-dose vaccine), in principle it should be administered to people with a “, Cravioto stressed at a press conference.

The Mexican expert clarified that this recommendation applies to all vaccines that the WHO has approved for emergency use against COVID-19: Pfizer-BioNTech, Moderna, AstraZeneca, Johnson & Johnson, Sinopharm and Sinovac.

The green light for a third dose comes after the WHO asked in August not to administer booster doses until the end of September given the persistent inequality in the distribution of anticovid vaccines, a deadline that was extended, weeks later, until January 2022 .

Before the WHO, the FDA had ruled against the request of the pharmaceutical company Pfizer, but opened the door for an additional dose to be administered to those with compromised immune systems and those who are in greater exposure, including the front-line workers, such as health workers.

Chinese vaccines need a third dose

In addition, the same group of WHO experts said that the Chinese vaccines developed by the Sinovac and Sinopharm laboratories – applied to the majority of health personnel in Peru -, based on inactivated viruses,

“All the evidence indicates that a third dose of these same vaccines or their counterparts is needed”, said Cravioto, chair of the WHO Strategic Advisory Group of Experts (SAGE), referring to the Chinese sera.

The WHO recommendation may affect vaccination programs not only in China, where most of the 2.2 billion doses administered are from these two laboratories, but also in countries in Latin America, Asia, Africa or Eastern Europe where it is They have imported and used these Chinese vaccines.

Cravioto indicated that these third doses, an age group that has shown greater problems of response to the coronavirus after being vaccinated with Sinovac or Sinopharm.

The SAGE expert, a group of experts that met last week to discuss global vaccination strategies, also opened the door for the third anticovid dose for people inoculated with Sinovac or Sinopharm (Pfizer, Moderna, Janssen, AstraZeneca).

Third dose reduces the risk of severe symptoms by 96%

The Government of Chile, which has administered 3.6 million booster doses of the covid-19 vaccine, published at the beginning of the month one of the first studies on the effectiveness of an additional injection and pointed out that it reduces by up to 96 % risk of hospitalization.

The research, which considered a total sample of 11.2 million people, analyzed the effectiveness of administering that they had completed their immunization scheme with the Chinese Coronavac, from the Sinovac laboratory, the majority in the country.

As clarified by Rafael Araos, the academic who led the study and one of the advisers of the Ministry of Health, all the analyzed vaccines “significantly” increased the effectiveness to prevent symptomatic disease with an extra dose.

Two weeks after a third injection, compared to 56% shown on average by those who only got two doses, according to the research.

Regarding hospitalizations, the third dose of AstraZeneca reduces its probability by 96%, that of Pfizer by 87% and that of Sinovac by 88%, compared to 84% protection of those who did not receive it.

“Scientific evidence shows that the protection of vaccines starts to wane over time. This finding, together with the threat of the Delta variant, ”said President Sebastián Piñera.

Avoided fourth wave in Israel

While the global debate on the use of the booster dose against COVID-19 continues, Israel claims the success of its campaign with the third Pfizer vaccine for the entire population, with which it was anticipated to the rest of the world and that, currently almost to an end.

At the end of July, without yet having the approval of international organizations or the US and EU health authorities, Israel, a measure progressively extended to the rest of the age groups that has contributed to reducing the rate of morbidity in the country.

In two and a half months, the campaign advanced rapidly and there are more than 3.7 million people – out of a total population of 9.3 – who received the booster dose. This was key in the strategy to face the fourth wave of coronavirus designed by the new coalition Executive headed by Naftali Benet.

Faced with the new peak in infections that skyrocketed this summer, attributed in part to the expansion of the contagious Delta variant, the government opted to keep the economy active.

Benet – who refused to impose a new confinement – bet heavily on the third dose and encouraged the population to get vaccinated, even with a campaign of telephone calls with automated messages in which he himself urged the Israelis to receive the puncture.

In turn, Health devised a new green pass system: those who have a full two-dose schedule in the last six months or those who have recovered from the virus in this same period of time are entitled to the certificate that allows them to access a whole series of public spaces or activities.

This conditioned that many were vaccinated to lead a normal life and it applies to many facilities, including universities, where students – who started the academic year the day before yesterday – must present their green pass if they want to attend face-to-face classes.

Agencies

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