Abstract
Purpose :
Intramuscular (im) SARS-CoV-2 vaccinations reduce the individual risk with a lack of sterile immunity. New pandemic waves are the result of this problem. Mucosal vaccines make sterile immunity. Thus we try “eye drop vaccination” with approved vaccines.
Methods :
32 syrian hamsters assigned to 4 groups of each 8. All hamsters were vaccinated 2 times 2 weeks apart. Two weeks after boost vaccination, all hamsters were exposed to a disease causing intranasal SARS-CoV-2 (Wuhan type) exposure (Challenge).
Group-1: Sham PBS-buffer; Group-2 epi-ocular live SARS-CoV-2; Group-3 im vaccination Jcovden® (Johnson&Johnson vaccine); Group-4: 20 ml of Jcovden® vaccine as eye drop onto left eye. During the whole experiment, hamsters monitored: weight, health, blood samples. After challenge each 2 hamsters of Group-3 and -4 were sacrificed at day 2, day 4, and 4 at day 5. After challenge, all hamsters had daily sampling of throat fluids for qPCR on RNA coding for protein- S, -N and ORF1AB.
Results :
During vaccination period, no group showed signs of local or systemic disease. The epi-ocular exposure to SARS-CoV-2 did not result in any systemic disease of the hamsters. After the second immunization hamsters showed high serum neutralizing antibodies against SARS-CoV-2 for the epi-ocular SARS-CoV2 exposed, the im and the epi-ocular J&J vaccination. No antibodies were found in the PBS group. After Challenge the PBS-“vaccinated” group showed severe weight loss and all signs of the SARS-CoV-2 disease. Hamsters being epiocular infected with SARS-CoV-2, im vaccinated and epi-ocular vaccinated hamsters stayed healthy. After epi-ocular SARS-CoV-2 and epi-ocular vaccinated hamsters showed high anti-SARS-CoV-2 IgA on their mucosa and in the blood. Anti SARS-CoV-2 IgG was high in these three groups and missing in the PBS group. The qPCR cycles increased to 28 up to 32 during the first 5 days after challenge in the immunized groups. This was not at all achieved for the sham vaccinated hamsters and first achieved for the epi-ocular SARS-CoV-2 infected hamsters followed by the epi-ocular and intramuscular vaccinated hamsters.
Conclusions :
With an epi-ocular vaccination of 2x 20 ml eye-drop full immunity against SARS-CoV-2 has been achieved in all cases. Hints on sterile immunity are high mucosal IgA in epi-ocular vaccinated hamsters. Immunity and strength of immunity against Influenza and Typhus have been proven for ocular vaccination previously.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.