Protection against SARS-CoV-2 transmission by a parenteral prime—Intranasal boost vaccine strategy
Dennis Christensen, Charlotta Polacek, Daniel J. Sheward, Leo Hanke, Ainhoa Moliner Morro, Gerald M. McInerney, Ben Murrell, Katrine Top Hartmann, Henrik Elvang Jensen, Gregers Jungersen, Kristin E. Engelhart Illigen, Louise Krag Isling, Rune Fledelius Jensen, Julia Sid Hansen, Ida Rosenkrands, Carlota Fernandez-Antunez, Santseharay Ramírez, Frank Follmann, Jens Bukh, Gabriel Kristian Pedersen
Abstract
BACKGROUND: Licensed vaccines against SARS-CoV-2 effectively protect against severe disease, but display incomplete protection against virus transmission. Mucosal vaccines providing immune responses in the upper airways are one strategy to protect against transmission. METHODS: We administered Spike HexaPro trimer formulated in a cationic liposomal adjuvant as a parenteral (subcutaneous - s.c.) prime - intranasal boost regimen to elicit airway mucosal immune responses and evaluated this in a Syrian hamster model of virus transmission. FINDINGS: Parenteral prime - intranasal boost elicited high-magnitude serum neutralizing antibody responses and IgA responses in the upper respiratory tract. The vaccine strategy protected against virus in the lower airways and lung pathology, but virus could still be detected in the upper airways. Despite this, the parenteral prime - intranasal booster vaccine effectively protected against onward SARS-CoV-2 transmission. INTERPRETATION: This study suggests that parenteral-prime mucosal boost is an effective strategy for protecting against SARS-CoV-2 infection and highlights that protection against virus transmission may be obtained despite incomplete clearance of virus from the upper respiratory tract. It should be noted that protection against onward transmission was not compared to standard parenteral prime-boost, which should be a focus for future studies. FUNDING: This work was primarily supported by the European Union Horizon 2020 research and innovation program under grant agreement no. 101003653.