Five months after immunization, two doses of the Pfizer-BioNTech vaccine appeared to offer virtually no defense against moderate illness caused by the Omicron variant — as measured by visits to emergency departments and urgent care clinics — among adolescents aged 12 to 17 years, according to data published on Tuesday by the Centers for Disease Control and Prevention.
But booster shots dramatically increased the protection, lending support to the agency’s recommendation of booster shots for everyone 12 and older.
These findings should be taken with caution. The agency’s study did not exclude unvaccinated adolescents who had some immunity from a prior infection, which may have made vaccination seem less effective than it was.
Researchers provided limited data on hospitalizations which are a more reliable proxy of severe disease than urgent care visits.
“One limitation of this data is that parents may bring their children to an urgent care or emergency department for a variety of reasons, and vaccine effectiveness by immunocompromised status, underlying health status, or vaccine product have not yet been examined,” the C.D.C. In a statement, the C.D.C.
Multiple studies have shown that the immune response is highly protective against hospitalizations, death, and even the highly contagious Omicron variant of infection.
A separate analysis of data from 29 jurisdictions posted on the C.D.C.’s website reported nine Covid-associated deaths among vaccinated children and adolescents aged 5 to 17 between early April 2021 and Jan. 2022, compared with 121 deaths in unvaccinated children of those ages.
Still, the findings suggest that scientists must carefully monitor the vaccine’s performance over time in children and adolescents, bearing in mind that boosters may be needed.
“We need to see more of these studies to see if this is consistent,” said Deepta Bhattacharya, an immunologist at the University of Arizona. “But I do think it’s likely, and we should be prepared as parents, that it’s going to take another shot.”
Parents will find the results particularly important as they consider whether to end mask mandates in schools across the country. The C.D.C. The C.D.C. published last week new guidance that suggested that approximately 70% of Americans can safely remove their masks from public indoor spaces.
The rate of vaccine uptake among children under five years old has been slow. More than half the adolescents aged 12-17 years have been fully vaccinated. They have received two shots, while 12% have received a third booster.
These findings follow data published Monday showing that only two doses provided little protection against Omicron variant infection in children aged five to eleven after one month. Even adults are less protected against infection, especially the Omicron variant. C.D.C. published new data. This trend can be seen on its website.
Researchers analyzed data on 39.217 visits to urgent care clinics, emergency departments, and 1,699 hospitalizations of children aged 5-17 years in 10 states. The data ranged from April. 9, 2021, to January 29, 2022.
In children aged 5 to 11, the vaccine’s ability to prevent moderate illness dropped to 46 percent about two months after full vaccination (two weeks after the second shot). The Omicron surge was the time when most of the visits to urgent care clinics and emergency rooms were made. This was also the time when older children and adults were more vulnerable than before the pandemic.
The vaccine’s effectiveness against moderate illness in adolescents held steady during the Delta era. 150 days after the full vaccination, effectiveness dropped to 38 percent among adolescents aged 12-15 years and to 46 percent for those 16-17 years.
Researchers analyzed data to determine if there was any protection in the Omicron period. They found that adolescents who had been vaccinated for moderate illness almost disappeared if they were not vaccinated within 150 days. A third dose of vaccine brought effectiveness back to 81 percent.
The findings are consistent with those from studies of adults showing that the vaccine’s effectiveness against infection and mild illness declined sharply over time, particularly after the arrival of the Omicron variant.
Effectiveness is the comparison of protection in unvaccinated and vaccinated populations. But as more of the population gains immunity through infection, it becomes harder to gain a true picture of vaccine effectiveness, said Paul Offit, director of the Vaccine Education Center at Children’s Hospital of Philadelphia and an adviser to the Food and Drug Administration.
“Are we comparing apples to apples when we say that the vaccine efficacy is going down?” he said.
It was still difficult to understand how protection against severe illness could be achieved. The results were not conclusive because there were not enough hospitalizations among the younger children. For adolescents who had been vaccinated over 150 days before, the effectiveness against severe illness was at least 70%.
However, most of those hospitalizations were during the Delta era so the data don’t provide any insight into the effectiveness against hospitalization since the Omicron variant emerged and spread.
The C.D.C. The C.D.C. recommends booster shots for Americans 12 years and older. Pfizer and BioNTech are currently evaluating the benefits of a third dose for younger children.
Source: NY Times