ChAdOx1 nCoV-19 vaccine prevents SARS-CoV-2 pneumonia in rhesus macaques.
van Doremalen N., Lambe T., Spencer A., Belij-Rammerstorfer S., Purushotham JN., Port JR., Avanzato VA., Bushmaker T., Flaxman A., Ulaszewska M., Feldmann F., Allen ER., Sharpe H., Schulz J., Holbrook M., Okumura A., Meade-White K., Pérez-Pérez L., Edwards NJ., Wright D., Bissett C., Gilbride C., Williamson BN., Rosenke R., Long D., Ishwarbhai A., Kailath R., Rose L., Morris S., Powers C., Lovaglio J., Hanley PW., Scott D., Saturday G., de Wit E., Gilbert SC., Munster VJ.
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerged in December 20191,2 and is responsible for the COVID-19 pandemic3. Vaccines are an essential countermeasure urgently needed to control the pandemic4. Here, we show that the adenovirus-vectored vaccine ChAdOx1 nCoV-19, encoding the spike protein of SARS-CoV-2, is immunogenic in mice, eliciting a robust humoral and cell-mediated response. This response was predominantly Th1, as demonstrated by IgG subclass and cytokine expression profiling. Vaccination with ChAdOx1 nCoV-19 (prime-only and prime-boost regimen) induced a balanced Th1/Th2 humoral and cellular immune response in rhesus macaques. We observed a significantly reduced viral load in bronchoalveolar lavage fluid and lower respiratory tract tissue of vaccinated rhesus macaques challenged with SARS-CoV-2 compared with control animals, and no pneumonia was observed in vaccinated animals. However, there was no difference in nasal shedding between vaccinated and control animals. Importantly, no evidence of immune-enhanced disease following viral challenge in vaccinated animals was observed. Safety, immunogenicity and efficacy of ChAdOx1 nCoV-19 against symptomatic PCR-positive COVID-19 disease will now be assessed in randomised controlled human clinical trials.