Unvaccinated Children Are an Important Link in the Transmission of SARS-CoV-2 Delta Variant (B1.617.2): Comparative Clinical Evidence From a Recent Community Surge

Objective To evaluate the necessity of Covid-19 vaccination in children aged < 12 y by comparing the clinical characteristics between unvaccinated children aged < 12 y and vaccinated patients aged >= 12y during the Delta surge (B.1.617.2) in Putian, Fujian, China. Methods A total of 226 patients with SARS-Cov-2 Delta variant (B.1.167.2; confirmed by Real-time PCR positivity and sequencing) were enrolled from Sep 10th to Oct 20th, 2021, including 77 unvaccinated children (aged < 12y) and 149 people aged >= 12y, mostly vaccinated. The transmission route was explored and the clinical data of two groups were compared; The effect factors for the time of the nucleic acid negativization (NAN) were examined by R statistical analysis. Results The Delta surge in Putian spread from children in schools to factories, mostly through family contact. Compared with those aged >= 12y, patients aged < 12y accounted for 34.07% of the total and showed milder fever, less cough and fatigue; they reported higher peripheral blood lymphocyte counts [1.84 (1.32, 2.71)x10<^>9/L vs. 1.31 (0.94, 1.85)x10(boolean AND)9/L; p<0.05), higher normal CRP rate (92.21% vs. 57.72%), lower IL-6 levels [5.28 (3.31, 8.13) vs. 9.10 (4.37, 15.14); p<0.05]. Upon admission, their COVID19 antibodies (IgM and IgG) and IgG in convalescence were lower [0.13 (0.00, 0.09) vs. 0.12 (0.03, 0.41), p<0.05; 0.02 (0.00, 0.14) vs. 1.94 (0.54, 6.40), p<0.05; 5.46 (2.41, 9.26) vs. 73.63 (54.63, 86.55), p<0.05, respectively], but longer NAN time (18 days vs. 16 days, p=0.13). Conclusion Unvaccinated children may be an important link in the transmission of SARS-CoV-2 delta variant (B1.617.2), which indicated an urgent need of vaccination for this particular population.

Automated summary

Unvaccinated children under the age of 12 showed milder symptoms during the Delta variant surge, but could be an important link in virus transmission.