Nantanee Rapisa, Jaru-Ampornpan Peera, Chantasrisawad Napaporn, Himananto Orawan, Papakhee Supawan, Sophonphan Jiratchaya, Tawan Monta, Jupimai Thidarat, Anugulruengkitt Suvaporn, Puthanakit Thanyawee
Center of Excellence for Pediatric Infectious Diseases and Vaccines, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.
Center of Excellence for Allergy and Clinical Immunology, Division of Allergy, Immunology and Rheumatology, Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, King Chulalongkorn Memorial Hospital, the Thai Red Cross Society, Bangkok, Thailand.
Vaccine X. 2023 Aug 5;15:100367. doi: 10.1016/j.jvacx.2023.100367. eCollection 2023 Dec.
Children 6 months to < 5 years old are recommended to receive 3-dose regimen of BNT162b2. Children previously infected with Omicron variant of SARS-CoV-2 develop immunity from natural infection, therefore may require fewer doses of vaccine.
To compare immunogenicity of 1- or 2-dose BNT162b2 in healthy children post COVID-19 with 3-dose BNT162b2 in COVID-naïve children.
Children aged 6 months to < 5 years who developed COVID-19 during the Omicron-predominant period were enrolled; Group A 3-6 months(N = 40) and Group B > 6 months(N = 40) prior to vaccination. Participants in Group A and B received 2-dose BNT162b2 intramuscularly 1 month apart. COVID-naïve children were enrolled as a control group (N = 40) and received 3-dose BNT162b2 at month 0,1,3. Neutralizing antibody against Omicron variant(BA.2.75 and BA.4/5) was determined by pseudovirus assays(pVNT) as reported by neutralization dilution for 50%inhibition (ID) at 28 days after the 1 and 2 dose.
From October-November 2022, 120 children with a median age of 2.8 years (IQR 1.6-4.0) were enrolled. The median duration since COVID-19 to vaccination was 4.4 months(IQR 3.8-5.4) in Group A and 7.9 months(7.0-8.5) in Group B. In Group A, the geometric means(GMs) of pVNT-BA.2.75 ID were 553 (95%CI 338-906) and 753(516-1098) after 1 and 2 doses, respectively, and the GMs of pVNT-BA.4/5 ID were 1936(1402-2673) and 1885(1414-2512), respectively. In Group B, the GMs of pVNT-BA.2.75 ID were 1383(1100-1742) and 1419 (1104-1823), and the GMs of pVNT-BA.4/5 ID were 2627(2048-3367) and 2056(1546-2735), respectively. Meanwhile in COVID-naïve group, the GMs of pVNT-BA.2.75 and pVNT-BA.4/5 ID were 158(98-255) and 59(31-114) after the 3 dose, respectively. The geometric mean ratio(GMR) of pVNT-BA.2.75 ID after 1 dose in Group A and B compared with after 3 doses in COVID-naïve group were 3.50 (1.93-6.34) and 8.74 (4.79-15.95), respectively. The GMR of pVNT-BA.2.75 ID after 1 dose in Group B compared with Group A was 2.50 (1.45-4.31).
Children previously infected with SARS-CoV-2 Omicron variant, developed robust neutralizing antibody response against Omicron variant after single-dose BNT162b2. Children with an interval of > 6 months since COVID-19 infection developed higher neutralizing antibody response compared to those with a 3-to-6-month interval.
建议6个月至未满5岁的儿童接种3剂BNT162b2疫苗。先前感染过新冠病毒奥密克戎变种的儿童可通过自然感染获得免疫力，因此可能需要较少剂量的疫苗。
比较新冠病毒感染康复后的健康儿童接种1剂或2剂BNT162b2疫苗与未感染新冠病毒的儿童接种3剂BNT162b2疫苗后的免疫原性。
招募在奥密克戎毒株为主的流行期间感染新冠病毒的6个月至未满5岁儿童；接种疫苗前，A组3至6个月（N = 40），B组大于6个月（N = 40）。A组和B组参与者肌肉注射2剂BNT162b2，间隔时间为1个月。招募未感染新冠病毒的儿童作为对照组（N = 40），在第0、1、3个月接种3剂BNT162b2。按照中和稀释法测定针对奥密克戎变种（BA.2.75和BA.4/5）的中和抗体，采用假病毒试验（pVNT）检测第1剂和第2剂接种后28天的50%抑制中和滴度（ID）。
2022年10月至11月，共招募了120名儿童，中位年龄为2.8岁（四分位间距1.6 - 4.0）。A组从新冠病毒感染到接种疫苗的中位时间为4.4个月（四分位间距3.8 - 5.4），B组为7.9个月（7.0 - 8.5）。在A组中，第1剂和第2剂接种后pVNT - BA.2.75 ID的几何均值（GMs）分别为553（95%CI 338 - 906）和753（516 - 1098），pVNT - BA.4/5 ID的几何均值分别为1936（1402 - 2673）和1885（1414 - 2512）。在B组中，pVNT - BA.2.75 ID的几何均值分别为1383（1100 - 1742）和1419（1104 - 1823），pVNT - BA.4/5 ID的几何均值分别为2627（2048 - 3367）和2056（1546 - 2735）。同时，在未感染新冠病毒的组中，第3剂接种后pVNT - BA.2.75和pVNT - BA.4/5 ID的几何均值分别为158（99 - 255）和59（31 - 114）。A组和B组第1剂接种后pVNT - BA.2.75 ID与未感染新冠病毒组第3剂接种后的几何均值比（GMR）分别为3.50（1.93 - 6.34）和8.74（4.79 - 15.95）。B组第1剂接种后pVNT - BA.2.75 ID与A组相比的几何均值比为2.50（1.45 - 4.31）。
先前感染过新冠病毒奥密克戎变种的儿童，接种单剂BNT162b2后对奥密克戎变种产生了强大的中和抗体反应。新冠病毒感染后间隔时间大于6个月的儿童比间隔3至6个月的儿童产生了更高的中和抗体反应。
