Virus World

Coronavirus disease 2019 (COVID-19), which is caused by infection with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has become a global pandemic. It currently remains unclear whether convalescing patients have a risk of reinfection. We generated a rhesus macaque model of SARS-CoV-2 infection that was characterized by interstitial pneumonia and systemic viral dissemination mainly in the respiratory and gastrointestinal tracts. Rhesus macaques reinfected with the identical SARS-CoV-2 strain during the early recovery phase of the initial SARS-CoV-2 infection did not show detectable viral dissemination, clinical manifestations of viral disease, or histopathological changes.

Comparing the humoral and cellular immunity between primary infection and rechallenge revealed notably enhanced neutralizing antibody and immune responses. Our results suggest that primary SARS-CoV-2 exposure protects against subsequent reinfection in rhesus macaques.

Published in Science (July 2, 2020):

https://science.sciencemag.org/content/early/2020/07/01/science.abc5343

Two new studies in macaques offer hope that humans could develop protective immunity against SARS-CoV-2, either as the result of a natural infection or by way of a vaccine. While there are differences between SARS-CoV-2 infection in macaques and humans, these findings - some of the first to show that non-human primates can develop protective immunity to SARS-CoV-2 - are promising in light of the ongoing efforts around the world to develop a vaccine and antibody treatments for COVID-19. An understanding of protective immunity to SARS-CoV-2 is critical for vaccine and public health strategies. A key unanswered question is whether infection with SARS-CoV-2 results in protective immunity against re-exposure; there is currently no data on whether humans are protected from re-exposure in this way. 

Earlier this year, research investigating cynomolgus macaques found these animals to be promising models for testing COVID-19 therapeutics. Here, in two new studies in rhesus macaques, researchers explored whether initial exposure to SARS-CoV-2 protected against reinfection and whether vaccination protected against infection, respectively. In a macaque model of SARS-CoV-2 infection they developed, and which recapitulated certain aspects of human SARS-CoV-2 infection, Abishek Chandrashekar, Ralph Baric, Dan Barouch and colleagues tested whether 9 adult animals who had cleared the virus were immune to viral re-challenge 35 days later. All 9 animals showed little to no symptoms after re-challenge and exhibited immune responses that protected against the second infection (given at the same doses as the first). Additional research will be required to define the durability of natural immunity shown here, the authors note. "Rigorous clinical studies will be required to determine whether SARS-CoV-2 infection effectively protects against SARS-CoV-2 re-exposure in humans," they say....

Original Studies  Published in Science (May 20, 2020):

https://doi.org/10.1126/science.abc4776

https://doi.org/10.1126/science.abc6284