SARS-CoV-2 Vaccines Elicit Durable Immune Responses in Infant Rhesus Macaques

Garrido, Carolina; Curtis, Alan D.; Dennis, Maria; Pathak, Sachi H.; Gao, Hongmei; Montefiori, David; Tomai, Mark; Fox, Christopher B.; Kozlowski, Pamela A.; Scobey, Trevor; Munt, Jennifer E.; Mallroy, Michael L.; Saha, Pooja T.; Hudgens, Michael G.; Lindesmith, Lisa C.; Baric, Ralph S.; Abiona, Olubukola M.; Graham, Barney; Corbett, Kizzmekia S.; Edwards, Darin; Carfi, Andrea; Fouda, Genevieve; Van Rompay, Koen K. A.; De Paris, Kristina; Permar, Sallie R.

Early life SARS-CoV-2 vaccination has the potential to provide lifelong protection and achieve herd immunity. To evaluate SARS-CoV-2 infant vaccination, we immunized two groups of 8 infant rhesus macaques (RMs) at weeks 0 and 4 with stabilized prefusion SARS-CoV-2 S-2P spike (S) protein, either encoded by mRNA encapsulated in lipid nanoparticles (mRNA-LNP) or mixed with 3M-052-SE, a TLR7/8 agonist in a squalene emulsion (Protein+3M-052-SE). Neither vaccine induced adverse effects. High magnitude S-binding IgG and neutralizing infectious dose 50 (ID50) >103 were elicited by both vaccines. S-specific T cell responses were dominated by IL-17, IFN-γ, or TNF-α. Antibody and cellular responses were stable through week 22. The S-2P mRNA-LNP and Protein-3M-052-SE vaccines are promising pediatric SARS-CoV-2 vaccine candidates to achieve durable protective immunity. One-Sentence Summary SARS-CoV-2 vaccines are well-tolerated and highly immunogenic in infant rhesus macaques