Hybrid immunity from SARS-CoV-2 infection and mRNA BNT162b2 vaccine among Thai school-aged children

Kanchanok Saraban; Piyarat Suntarattiwong; Napaporn Chantasrisawad; Sophida Boonsathorn; Pope Kosalaraksa; Wanatpreeya Phongsamart; Auchara Tangsathapornpong; Peera Jaruampornpan; Suchada Srisarang; Thanyawee Puthanakit; KIDSVAX study team

doi:10.1016/j.jvacx.2023.100414

Hybrid immunity from SARS-CoV-2 infection and mRNA BNT162b2 vaccine among Thai school-aged children

Vaccine X. 2023 Nov 24:15:100414. doi: 10.1016/j.jvacx.2023.100414. eCollection 2023 Dec.

Affiliations

¹ Queen Sirikit National Institute of Child Health, Bangkok, Thailand.
² Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.
³ Center of Excellence for Pediatric Infectious Diseases and Vaccines, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.
⁴ Thai Red Cross Emerging Infectious Diseases Clinical Center, King Chulalongkorn Memorial Hospital, Bangkok, Thailand.
⁵ Department of Pediatrics, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand.
⁶ Pediatric Infectious Disease Unit, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand.
⁷ Division of Infectious Diseases, Department of Pediatrics, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand.
⁸ Division of Infectious Diseases, Department of Pediatrics, Faculty of Medicine, Thammasat University, Pathum Thani, Thailand.
⁹ Virology and Cell Technology Research Team, National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency (NSTDA), Pathum Thani, Thailand.

Abstract

Objective: To compare the immune response of hybrid immunity - arising from SARS-CoV-2 infection and mRNA BNT162b2 vaccination - to that of 2-doses of vaccine.

Methods: In a subanalysis of BNT162b2 vaccine trial in 5 to 11-year-old children, There were 179 children who had hybrid immunity compared with 134 children with solely 2-dose vaccine. The immunological outcome was a surrogate virus neutralization test (sVNT) against the Omicron strain, BA.1, (%inhibition). An sVNT level ≥68 % inhibition was considered as protective immune response.

Results: From February to April 2022, 179 children had COVID-19 natural infection resulting in hybrid immunity included: Group1;prior vaccination(n = 17), Group2;after the first dose(n = 61), and Group3;after the second dose(n = 97). The proportion of children with protective immune response was higher in Group 3 and Group 1 - 61.9 % and 58.8 %, compared to 36.1 % and 34.3 % in Group 2 and comparator group (2 doses of vaccine), respectively. The geometric mean % inhibition of sVNT was higher in Group 1 (68.5, 95 %CI 55.5-84.6) and Group 3 (63.5, 95 %CI 55.5-72.6), followed by comparator group (49.6, 95 %CI 44.8-54.9) and Group 2 (42.1, 95 %CI 34.6-51.3), p < 0.001.

Conclusions: Immune response that arises from BNT162b2 vaccine after natural infection and infection after 2 doses of BNT162b2 was higher than infection after partially-vaccinated children.

Keywords: BNT162b2; Hybrid immunity; Neutralizing antibody; Omicron variant; SARS-CoV-2; School-aged children.