ABSTRACT
The SARS-CoV-2 Omicron variant and its sublineages continue to cause COVID-19—associated pediatric hospitalizations, severe disease, and death globally. BNT162b2 and CoronaVac are among the top most widely used COVID-19 vaccines. Much less is known on the Wuhan-Hu-1 strain based vaccines in the pediatric population compared to adults. Given the worldwide need for booster vaccinations to stimulate the immune response against new Omicron variants of SARS-CoV-2, we characterized the humoral and cellular immune response against Omicron variant BA.1 in a pediatric population aged 10 to 16 years who received heterologous vaccination based on two doses CoronaVac, two doses CoronaVac (2x) plus one booster doses BNT162b2 [CoronaVac(2x) + BNT162b2 (1x)], two doses CoronaVac plus two booster doses BNT162b2 [CoronaVac(2x) + BNT162b2 (2x)], and three doses BNT162b2. We observed that [CoronaVac(2x) + BNT162b2 (2x)] vaccination showed higher anti-S1 and neutralizing antibody titers and CD4 and CD8 T cell immunity specific to the Omicron variant compared to immunization with two doses CoronaVac alone. Furthermore, from all groups tested, immunity against Omicron was highest in individuals who received three doses BNT162b2. We conclude that booster vaccination with BNT162b2 promotes greater immunity against SARS-CoV-2 in the pediatric population compared to two doses CoronaVac alone.
Subject(s)
Death , COVID-19ABSTRACT
Background: In January 2021, the city of Concepción in Chile suffered a second wave of COVID-19, while in early April 2021, all of Chile was facing the same situation. This generated the need to modify and validate a methodology for detecting severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in saliva, thereby expanding the capacity and versatility of testing.Methods: People who came to the health center in Concepción city to perform a test of real-time reverse transcription polymerase chain reaction (RT-PCR) from a nasopharyngeal swab (NPS) specimen were invited to participate in this study. A total of 131 participants agreed to sign an informed consent and provide saliva and NPS specimens to validate a methodology in terms of sensitivity, specificity, and statistical analysis of the Ct values from RT-PCR.Findings: Calculations pertaining to the 127 participants who were ultimately included in the analysis were the following: sensitivity at 94·34% (95% CI: 84·34%-98·82%) and specificity at 98·65% (95% CI: 92·70%-99·97%). The saliva specimen showed a very similar performance to NPS as demonstrated with the diagnostic parameters.Interpretations: This RT-PCR methodology from the saliva specimen is a highly sensitive and specific alternative as compared to the reference methodology, which uses an NPS specimen. This modified and validated methodology is intended for use in the in vitro diagnosis of SARS-CoV-2, which provides health authorities in Chile and local laboratories with a real alternative for RT-PCR from NPS.Funding Information: Health Public Institute of Chile.Declaration of Interests: All authors declare no competing interests.Ethics Approval Statement: The study had the authorization of the Scientific Ethics Committee of the Health Service of Concepción, Chile Number 20-01-02. Parents or legal guardians for volunteers under the age of 18 signed the informed consent.