Longitudinal Follow-up of Antibody Responses in Pediatric Patients With COVID-19 up to 9 Months After Infection

• Published in: The Pediatric infectious disease journal Vol. 40; no. 8; pp. e294 - e299
• Main Authors: Oygar, Pembe Derin, Ozsurekci, Yasemin, Gurlevik, Sibel Lacinel, Aykac, Kubra, Kukul, Musa Gurel, Cura Yayla, Burcu Ceylan, Ilbay, Sare, Karakaya, Jale, Teksam, Ozlem, Cengiz, Ali Bulent, Ceyhan, Mehmet
• Format: Journal Article
• Language: English
• Published: Lippincott Williams & Wilkins 01-08-2021
• ISSN: 0891-3668; 1532-0987
• DOI: 10.1097/INF.0000000000003199

Introduction:
Antibody response developed within 2–3 weeks after exposure to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been shown to decrease over time; however, there is limited data about antibody levels at 6 months or later postinfection, particularly in children.
Materials and Method:
A prospective multicenter study was performed using 315 samples of 74 confirmed and 10 probable coronavirus disease 2019 pediatric cases. About 20% of these cases were classified as asymptomatic, 74% as mild/moderate and 6% as severe/critical. Patients were included if at least 2 samples were available. The antibody response was classified as either early-period or late-period (14 days–3 months and after 6 months, respectively) for IgG response whereas IgA response was tested on various time intervals, including as early as 4 days up to 3 months. Euroimmun Anti-SARS-CoV-2 IgG and IgA and Genscript SARS-CoV-2 Surrogate Virus Neutralization Kits were used for antibody detection.
Results:
There was no difference between the early-period and late-period IgG positivity (
P
= 0.1). However, the median IgG levels were 11.98 in the early periods and 4.05 in the late periods, with a significance of
P
< 0.001. Although the decrease in IgG levels was significant in asymptomatic and mild/moderate cases (
P
< 0.008 and
P
< 0.001, respectively), the decrease in severe/critical cases was moderate (
P
= 0.285). The sensitivity of the IgG after 15 days was higher than 94%, and the sensitivity of IgA was 88% on days 8–15.
Conclusion:
SARS-CoV-2 IgG antibody levels decreased after 6 months. The decrease was moderate in severe/critical cases. Overall, 95.8% of the patients remained positive up to 9 months after infection. Although the IgA response may be useful early on, the IgG response is useful after 14 days.