Vaccination against SARS-CoV-2 in UK school-aged children and young people decreases infection rates and reduces COVID-19 symptoms

Abstract

Background We aim to explore the effectiveness of one-dose BNT162b2 vaccination upon SARS-CoV-2 infection rates in children and young people (CYP) during Delta and Omicron variant predominance in the UK, and study its effect on COVID-19 presentation and post-vaccination symptoms. Methods In this prospective longitudinal cohort study, we analysed data from 115,775 CYP aged 12-17 years, proxy-reported through the Covid Symptom Study (CSS) smartphone application. We calculated post-vaccination infection risk after one dose of BNT162b2. We described the illness profile of CYP with post-vaccination SARS-CoV-2 infection, compared to unvaccinated CYP. Findings Between August 5, 2021 and February 14, 2022, 25,971 UK CYP aged 12-17 years received one dose of BNT162b2 vaccine. Vaccination reduced infection (reporting) risk (-80.4% and -53.7% at 14-30 days with Delta and Omicron variants respectively, and -61.5% and -63.7% after 61-90 days). The probability of remaining infection-free diverged after vaccination, and was more robust with prior infection. Vaccinated CYP who contracted SARS-CoV-2 during the Delta period had milder disease than unvaccinated CYP; however, during the Omicron period this was only evident in children aged 12-15 years, and overall disease profile was similar in both vaccinated and unvaccinated CYP. Post-vaccination local side-effects were common, systemic side-effects were uncommon, and both resolved quickly. Interpretation One dose of BNT162b2 vaccine reduced risk of SARS-CoV-2 infection for at least 90 days in CYP aged 12-17 years. Vaccine protection was modulated by SARS-CoV-2 variant type (lower for Omicron than Delta variant), and was enhanced by pre-vaccination SARS-CoV-2 infection. Severity of COVID-19 presentation after vaccination is generally milder, although unvaccinated CYP also have an uncomplicated course. Overall, vaccination was well-tolerated.

Comparison of the prevalence of SARS-CoV-2 nucleoprotein antibodies in healthcare workers and an unselected adult and paediatric all-comer patient population: insights from a longitudinal study of healthcare workers and concurrent serial cross-sectional studies of patients at an academic medical centre in Austria

“…Second, these findings indicate greater transmission in children than had previously been assumed 15. This knowledge is essential because vaccination had not been approved for children <5 years old 19…”

“…15 This knowledge is essential because vaccination had not been approved for children <5 years old. 19 High rates of transmission pose other dangers as well: in addition to acute SARS-CoV-2 infections, children and adults can develop long-term sequelae, such as fatigue, 20 impaired exercise capacity, cognitive disturbances and changes in brain structure, 21 and cardiovascular complications, 22 including arrhythmias, inflammatory heart disease, heart failure and thromboembolic disease. Although patients with more severe COVID-19 during the acute phase of the infection were more likely to develop significant health problems, these risks and burdens were evident even among not hospitalised individuals.…”

A methodological framework for assessing the benefit of SARS-CoV-2 vaccination following previous infection: case study of five to eleven year olds

“…Before Omicron emerged at the end of 2021, when most children had not yet been infected and the vaccine displayed excellent efficacy [1][2][3], roll-out in the US [4], Israel and European countries was motivated by a desire to prevent adverse outcomes in children infected with COVID-19 for the first time. The Omicron SARS-CoV-2 variant proved both more transmissible and more immune evasive, with more rapid waning of protection from previous infection or vaccination [2,[5][6][7][8][9][10][11][12][13][14], and a much higher incidence of reinfections [15]. Protection against new infection and subsequent hospitalisation has been shown to be highest in children who had both vaccination and previous infection [3,9,10].…”