Covid vaccines were developed, tested on thousands of people and approved at a time when the form of the circulating coronavirus was the ancestral or strains of least concern.
The arrival of more transmissible and vaccine-escaped variants, such as ômicron, showed that a third dose in adults is necessary to maintain protection against the disease and its more severe forms.
Pfizer’s Covid vaccine for children aged five years and older, with a different formulation from that for the older public, was approved and started to be used in the US and other countries at the end of 2021. As for adolescents aged 12 to 17 years, the immunizer from the American laboratory has the same dosage as that for adults.
The results of controlled and randomized phase 3 studies by the pharmaceutical company showed a 100% efficacy of the vaccine in adolescents, and 90.7% in children aged 5 to 11 years.
In Chile, as well as in Brazil, Coronavac was also approved for children and adolescents, aged 6 to 17 years, in the Brazilian case, and for those aged 3 years and over, in the neighboring country.
Data on the effectiveness (ie, real-life efficacy) of these vaccines are now beginning to emerge, particularly in the context of the omicron variant.
According to a study by Chilean researchers published on February 22, Coronavac induced a good immune response of both antibodies and memory cells in subjects aged 3 to 17 years who received one or two doses of the vaccine until December 31, still early. of the micron circulation.
The most common side effects of the vaccine were pain at the injection site and headache, recorded in greater numbers by adolescents than in children, indicating good safety in the youngest.
Even with a drop in the ability to protect against the omni, the antibody response generated four weeks after the second dose was greater than that observed in adults.
Yellow sign in New York
Last Monday (28), a study, coordinated by researcher Eli Rosenberg, from the New York State Department of Health, indicated a significant drop in the protection of the Pfizer vaccine in children aged 5 to 11 years.
Before the omicron, the effectiveness of the vaccine against infection was 68% in this age group, falling to 12% at the end of January. In adolescents aged 12 to 17 years vaccinated with the immunizer, protection dropped from 66% to 51% against symptomatic cases of Covid. In both age groups, protection for hospitalizations and deaths, however, remained high.
The research, which evaluated data from 852,384 12- to 17-year-olds and 365,502 5- to 11-year-olds who received the immunizer in New York state, was released on the online preprint platform medRxiv and is still awaiting peer review. The study period was from December 13, 2021 to January 30, 2022, therefore, within the omicron wave.
In addition to the difference in effectiveness in the two age groups, the researchers were able to observe that, for an 11-year-old child in the week of January 24, the effectiveness was only 11% against infection, while for a 12-year-old child on the same date, it was only 11% effective. of 67%.
This indicates a dose-related difference, as children up to 11 years old receive the equivalent of one third (10µg) of the dose given to adults and adolescents of 30µg. The result, therefore, indicates that this dosage may not be sufficient to prevent infection.
According to Renato Kfouri, pediatrician and president of the immunization department of the Brazilian Society of Pediatrics, the data from the study carried out in New York should not, however, be extrapolated to other scenarios with other vaccine coverage, with different dose intervals and with an epidemiological situation. distinct, as is the case of Brazil.
The use of Coronavac, in addition to the Pfizer vaccine, requires specific studies in Brazil in order to understand the effectiveness of vaccines in the country’s young population. These data have not yet been published here.
Booster shows its role
Last Tuesday (1st), the CDC (US Centers for Disease Control and Prevention) released data on the effectiveness of the Pfizer vaccine in the public aged 5 to 11, 12 to 15 and 16 to 17. According to the survey, which included more than 40,000 hospitalization data for these age groups from April 9, 2021 to January 29, 2022, the effectiveness for all groups showed a reduction, but it was smaller than that observed in Rosenberg’s work in New York .
In children aged 5 to 11 years, vaccine protection for needing hospital care or hospitalization for Covid was 46% (from 14 to 67 days after the second dose). In the case of adolescents aged 12 to 15 years and 16 to 17 years, who were vaccinated longer, the effectiveness was 83% and 76%, respectively, from 14 to 149 days after the second dose, and 38% and 46% for those vaccinated for five months or more.
In 16- and 17-year-olds who received a booster dose, vaccine efficacy was, however, recovered to 86% a week or more after the additional dose.
For Juarez Cunha, pediatrician and president of Sbim (Brazilian Society of Immunizations), the studies further reinforce the need to vaccinate children.
“The data point to what we already know, that vaccines do not prevent infection, especially in children aged 5 to 11 years, but at the same time they come to the conclusion that protection against severe forms is high”, he says.
For Cunha, in Brazil, the moment is one of attention. “Children are at high risk of infection because vaccination coverage is still low,” she explains.
Cunha also recalls that the vaccines were formulated in a period with the ancestral variant of the virus in circulation or other variants, such as delta. “It’s not just the ômicron, other variants also caused a loss of immunity, which is why we evaluated the change in the vaccination schedule in adults with the booster”, recalls the doctor.
More hospital admissions with omicron
On Wednesday (2), an article published in The New England Journal of Medicine with data from the largest European hospital service, in Paris, showed that, with the change from delta to omicron, the number of children requiring hospitalization for respiratory disease grew. 233%, including children who were healthy.
The hospital analysis also found that none of the hospitalized children aged 12 years and older were fully vaccinated (with two doses).
Data from the American Academy of Pediatrics as of February 24th reported about 4.8 million cases of Covid in children since January 1st, 2022. In the week of January 20th alone, according to the Medical Society, there were more than 1.15 million cases.
During the period of December and January, hospitalizations of children in the United States for Covid exploded, with about 700 children hospitalized per day, the highest number since the beginning of the pandemic.
Covid hospitalizations in children reported for 25 states and New York City ranged from 1.4% to 4.6% of total population-wide cumulative hospitalizations, with 0.1% to 1.5% of cases of Covid-19. Covid in a child resulting in hospitalization.
A study done by Seattle Children’s Hospital also showed that the omicron caused an increase in the number of hospitalizations for laryngitis in children from December 1, 2021 to January 15, 2022.
Chad-98Weaver, a distinguished author at NewsBulletin247, excels in the craft of article writing. With a keen eye for detail and a penchant for storytelling, Chad delivers informative and engaging content that resonates with readers across various subjects. His contributions are a testament to his dedication and expertise in the field of journalism.
