Pfizer / BioNTech vaccine against covid-19: what we know so far

(CNN Spanish) – Pfizer and BioNTech said Thursday that they are requesting emergency use authorization from the U.S. Food and Drug Administration (FDA) for their covid-19 vaccine for children ages 5 to 11. years.

Last month, Pfizer released details of a phase 2/3 trial that showed its COVID-19 vaccine was safe and elicited a “robust” antibody response in children ages 5 to 11. The trial included 2,268 participants aged 5 to 11 years and used a two-dose regimen of the vaccine given 21 days apart. This trial used a 10-microgram dose, lower than the 30-microgram dose that has been used for those over 12 years of age.

If approved, it would be the first vaccine against covid-19 for young children. Here’s what you need to know about the Pfizer / BioNTech vaccine.

How does this vaccine work?

The vaccine developed by Pfizer and BioNTech uses messenger RNA, or mRNA. This is a strand of the genetic code that cells can “read” and use to produce a protein, in the case of the COVID-19 vaccine, it encodes a fragment of the coronavirus spike protein.

The mRNA then instructs the cells to produce the particular part of the virus spike protein. Thus, the immune system sees it, recognizes it as foreign and is prepared to attack when a real infection occurs.

The vaccine is currently two doses.

What is its effectiveness and what about immunity against the delta variant?

When the Pfizer / BioNTech vaccine began rolling out late last year, there was talk of being 95% effective in preventing symptomatic covid-19 disease.

But that was before the more transmissible delta variant of the coronavirus was detected and rated by the World Health Organization and the US Centers for Disease Control and Prevention (CDC) as a “variant of concern.” .

In June, preliminary findings from a study in Scotland that was published in The Lancet found that the Pfizer vaccine provided 79% protection against all delta variant infections, compared with 92% against the alpha variant.

In short, what does all this mean? That although the data shows that there would be a greater chance of getting the delta variant compared to coronavirus strains, the Pfizer / BioNTech vaccine is still more than 90% effective in preventing serious illness and hospitalization.

Combine vaccines?

Given the concern about the spread of new variants of the coronavirus – and in the face of eventual logistical problems in the local deployment of vaccines – experts have been studying the effectiveness of combining different vaccines against covid-19.

In late June, a preliminary report from the Com-CO study, which has not yet been peer-reviewed, found that combining the Oxford / AstraZeneca and Pfizer / BioNTech drugs induced strong immune responses against COVID-19.

Dr Matthew Snape, the trial’s principal investigator and associate professor of Pediatrics and Vaccination at the University of Oxford, said during a Science Media Center briefing on June 28 that those in the study who received a dose of the vaccine against AstraZeneca’s covid-19 followed by a dose of the Pfizer vaccine four weeks later elicited higher levels of antibody and T-cell responses than those who received two AstraZeneca vaccines.

Those who received a Pfizer vaccine followed by a dose of AstraZeneca had a lower antibody response compared to the two doses of the Pfizer vaccine, but similar T-cell responses.

However, more research is needed to see if these mixed vaccine schemes work in the real world. Furthermore, the authors noted that the study has some limitations such as the sample size and the age of the participants, all over 50 years of age.

On the other hand, since June 21, based on a recommendation from the Immunization Department, the Chilean health authorities began offering a second dose of Pfizer to men under 45 years of age who received a first dose of AstraZeneca. This, after announcing the suspension of vaccination in this population group, since a case of thrombosis was known in a 31-year-old man.

Booster dose

In September, the FDA
authorized the emergency use of a booster dose of Pfizer’s Covid-19 vaccine in people 65 and older, those at risk of serious illness, and people whose jobs put them at risk of infection.

“Today’s action demonstrates that currently available science and data continue to guide FDA decision-making for covid-19 vaccines during this pandemic,” said FDA Acting Commissioner Dr. Janet Woodcock , it’s a statement.

Pfizer had requested full approval of a booster dose for all people 16 years of age and older who have already received both doses of the vaccine. The company argued that there was evidence that immunity waned over time.

This week, meanwhile, the Committee for Human Medicines of the European Medicines Agency (EMA) authorized the use of a booster dose for Pfizer and Moderna vaccines for the population between 18 and 55 years old who have already completed their scheme. immunization against covid-19.

With information from Maggie Fox, Dakin Andone, Ivana Kottasová, Naomi Thomas, Jessica Hasbun and Juan Carlos Paz.