Findings of Karnataka’s third sero-survey involving 5,358 unvaccinated children aged six to 14 found that 75.38% of them have been exposed to the coronavirus so far.
Taken up following recommendations by the State’s COVID-19 Technical Advisory Committee (TAC), the survey began on June 6. It was aimed at understanding the active COVID-19 infection, the prevalence of COVID-19 antibodies, the waning of antibodies following natural infection, the incidence of re-infection, and the prevalent strain of SARS-CoV-2 in children.
The survey covered children in both urban and rural areas in all districts, including the Bruhat Bengaluru Mahanagara Palike (BBMP) areas. Samples of children who had symptoms but tested negative for COVID-19 were tested for other influenza diseases.
“Of the 5,358 participants surveyed, 29 samples were rejected, and 5,329 had a valid IgG result. The crude seroprevalence of IgG antibodies against SARS-CoV-2 was 70.11% as of June 14, 2022, which was the end date for the paediatric sero-survey. The overall adjusted seroprevalence of IgG was 75.38% at the State level, obtained after adjusting for the sensitivity and specificity of the antibody testing kit,” stated the survey report released on Thursday.
Case to Infection ratio
The case-to-infection ratio was found to be 1:37 based on the total reported COVID-19 cases in the age group of six to 14 (2,23,750) as of June 14.
Of the 5,358 participants, 2,726 (50.9%) were boys and 2,632 (49.1 %) were girls. While 1,662 (31%) were in the six to eight age group, 1,917 (35.8%) were in the nine to 11 age group and the rest 1,779 (33.2%) were in the 12 to 14 age group.
While 1,625 (30.3%) were from urban slums, 1,681 (31.4 %) were from non-slum urban areas and the rest 2,052 (38.3%) were from rural areas. The percentage of school-going participants was 93.5% (5,013).
A total of 709 (13.23%) participants were symptomatic and the remaining 4,649 (86.77%) were asymptomatic during the survey.
High in female children
Among the participants with valid IgG results, IgG positivity was higher in females (77.83%) than in males (73.02%). Participants from non-slum urban areas had slightly higher IgG positivity of 77.96% as compared to those from rural areas, which was found to be 71.98%.
While the highest seroprevalence of IgG was in Chikkamagaluru at 100%, the lowest was in Kalaburagi at 43.24%. Chikkamagaluru was followed by Bagalkot (91.12%), Uttara Kannada (89.61%), Gadag (88.62%), and BBMP area (86.88%).
Nearly 87% paediatric seroprevalence in BBMP areas
The survey found that overall 86.88% of children in the Bruhat Bengaluru Mahanagara Palike (BBMP) areas were exposed to SARS-CoV-2. While the highest seroprevalence of IgG was seen in the East Zone (95.19%), Yelahanka (94.69%) and Rajarajeshwarinagar (91.64%) followed.
Dasarahalli Zone (62.37%) had the lowest seroprevalence followed by Bommanahalli (81.51%) and Mahadevapura (82.47%).
Active infection
Of the 5,358 participants surveyed, 23 samples had inconclusive results and 29 were rejected, thereby giving a total of 5,278 valid RT-PCR results. Among the valid RT-PCR reports, only two (0.04%) were RT-PCR positive, one symptomatic participant from Udupi and one asymptomatic participant from Chitradurga.
Genome sequencing
While the strain of SARS-CoV-2 of the symptomatic COVID-19 positive was found to be BA.5 Omicron, the strain of SARS-CoV-2 of the asymptomatic COVID-19 positive was found to be BA.2.10 Omicron
Incidence of other influenza infections
Among the 708 symptomatic but COVID-19 negative children, 584 samples were sent for an ILI panel of tests, of which 497 had valid ILI results. Among all those tested for the ILI panel of tests, 32 (6.44%) were found positive for influenza A (H1N1), and one (0.2%) was found positive for influenza B.
