According to a study published in the Jama Network, shortly after being designated a variety of concern on November 26, 2021, the SARS-CoV-2 Omicron (B.1.1.529) variant quickly replaced the Delta (B.1.617.2) variant globally and had become the dominant variant in the United States by late December 2021.
The United States saw the highest rate of confirmed COVID-19 infections between December 2021 and February 2022. By the end of February 2022, it is expected that 58% of Americans will have serologic evidence of having been infected with SARS-CoV-2 in the past. Children aged 5 to 11 had the most excellent seropositivity rate (77%).
The BNT162b2 vaccine from Pfizer and BioNTech against COVID-19 was licensed for use in the United States on November 2, 2021, and is suggested for use in a 2-dose regimen in children aged 5 to 11. The Centers for Disease Control and Prevention suggested that children aged 5 to 11 receive a BNT162b2 booster dosage at least five months after completing the first series on May 19, 2022.
Before June 24, 2022, the United States recommended only BNT162b2 for this age group. On October 12, 2022, the Centers for Disease Control and Prevention (CDC) recommended augmenting current (bivalent) COVID-19 vaccines in children aged 5 to 11 at least two months after the initial booster vaccinations.
According to the existing data on vaccination efficacy, two doses of BNT162b2 offered modest protection (about 30%-60% VE) against Omicron-related infection,11-14 symptomatic COVID-19,11,14,15 and COVID-19-related urgent or emergency care visits16 in children aged 5-11 years (VE). There is no evidence of the VE of a booster dosage in this age range.
More crucially, because of the current pandemic, it is becoming increasingly necessary to evaluate vaccine effectiveness by stratifying VE calculations by the history of past infection, as there is now high seroprevalence within this age range.
Since Walgreens is the largest drugstore chain in the United States and Puerto Rico, with over 7200 retail pharmacy locations, electronic health data from the firm were used in this case-control research. Beginning in the autumn of 2020, Walgreens has partnered with Aegis Sciences Corp, a national health care laboratory, to increase the accessibility, efficiency, and credibility of COVID-19 testing at more than 5200 of the chain’s pharmacies.
By September 30, 2022, Walgreens and Aegis had performed over 10 million SARS-CoV-2 polymerase chain reaction (PCR) tests, with 626 000 of those tests performed on children aged 5 to 11. Upon check-in, patients were asked to complete a self-reported questionnaire, which included questions about their demographics, current symptoms, and medical history.
The risk of COVID-19-related morbidity and the proportion of the population immunized varies by race and ethnicity. The parent or guardian self-reported the child’s race and ethnicity using CDC-defined categories; due to limited sample size, the CDC-defined categories of American Indian or Alaska Native and Native Hawaiian or Other Pacific Islander were merged into a single category.
Given the current state of Omicron dominance and high seroprevalence, this test-negative case-control investigation found that two doses of BNT162b2 provided moderate short-term protection against Omicron infection in children aged 5 to 11 years. Although children with a history of illness had a greater estimated efficacy, protection for all children began to wane about three months after the second dosage.
After the effects of the original Omicron vaccination wore off, a (monovalent) booster dose restored immunity and offered some protection for another three months. This study found that individuals with and without a history of COVID-19 benefit from booster doses to prevent SARS-CoV-2 infection for the first time.
