Rapid development of COVID-19 vaccines has helped mitigating SARS-CoV-2 spread, but more equitable allocation of vaccines is necessary to limit the global impact of the COVID-19 pandemic and the emergence of additional variants of concern. We have developed a COVID-19 vaccine candidate based on Newcastle disease virus (NDV) that can be manufactured at high yields in embryonated eggs. Here, we show that the NDV vector expressing an optimized spike antigen (NDV-HXP-S) is a versatile vaccine inducing protective antibody responses. NDV-HXP-S can be administered intramuscularly as inactivated vaccine or intranasally as live vaccine. We show that NDV-HXP-S GMP-produced in Vietnam, Thailand and Brazil is effective in the hamster model. Furthermore, we show that intramuscular vaccination with NDV-HXP-S reduces replication of tested variants of concerns in mice. The immunity conferred by NDV-HXP-S effectively counteracts SARS-CoV-2 infection in mice and hamsters.

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Recombinant human adenoviruses (Ads) (types 4, 5, and

Both adult and baby hamsters infected intranasally with human adenovirus type 5 exhibited virologic, serologic, and histologic evidence of infection. When 8-day old hamsters were infected with 4 x 10(6) pfu, concentrations of virus up to 2 x 10(6) pfu/animal were detected in the lung, peaking on day 2. The minimum infectious dose was 1 x 10(3) pfu/animal. This model may be useful in studies of conventional and recombinant adenoviral vaccines for humans.