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

Abstract

ObjectiveTo 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.MethodsA 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.ResultsThe 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)×10^9/L vs. 1.31 (0.94, 1.85)×10^9/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).ConclusionUnvaccinated 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.

Assessing the transition of COVID-19 burden towards the young population while vaccines are rolled out in China*

“…However, the importations of Delta variant infections caused dozens of local outbreaks [ 13 ], the largest of which occurred in Xi’an city and led to 2050 reported cases and a city-wide lockdown [ 14 ]. Similar to what was observed in other countries, the Delta surge was characterized by a high proportion of infections in children (eg 77/226 reported cases in Putian city, China were younger than 12 years) [ 15 ].…”

“…These modelling results obtained for China are backed up by empirical evidence from other countries, where an upsurge of COVID-19 cases and hospitalizations among children and adolescents has been reported since the summer of 2021 [ 10 , 11 , 44 ]. Evidence of this epidemiological shift towards children and adolescents also comes from the analyses of local outbreaks in Putian city, China, in September 2021, where 34.1% of the reported cases occurred in those aged 0–11 years [ 15 ].…”

The effects of vaccination on the disease severity and factors for viral clearance and hospitalization in Omicron-infected patients :A retrospective observational cohort study from recent regional outbreaks in China

“…The total number of infected persons in the Omicron group and the Delta group was 3,265 and 266, respectively. The median age of the Omicron-infected patients was higher than that of the Delta-infected patients [36 (25,48) vs. 32 (9,46)] 14 ; the most common primary diseases in both groups were hypertension (5.61% vs. 2.65%) and diabetes (2.62% vs. 4.87%); 16 pregnant women were found in the Omicron group.…”

“…All the SARS-Cov-2 cases with positive nucleic acid during two recent regional outbreaks in Fujian, China (from 2021 to the present) were confirmed by fluorescence real-time PCR (RT-PCR) during two recent regional outbreaks in Fujian, China from 2021 to the present. They were divided into the Omicron group: 3,265 Omicron BA.2-infected patients in Quanzhou City, Fujian, China between March 13 and May 6, 2022; and the Delta group 14 : 226 Delta-infected patients (Delta B.1.167.2) in Putian City, Fujian, China from September 10 to October 20, 2021. Different from previous foreign studies 15 that only included symptomatic populations, this study enrolled all nucleic acid-positive cases in the regional outbreaks, including asymptomatic and mild patients.…”

“…16 The Delta group received the same treatment schemes, except for Nematevir/Ritonavir, which was not yet available then. 14…”