Growing data in NHP (non human primate aka monkey) supporting presence of at least some degree of immunity after recovery from SARS-CoV-2. Add SinoVac monkey data showing their vaccine candidate protects monkeys from SARS-CoV-2 infection. Odds of successful vaccine development improving, I think. Time for this remains uncertain.
https://science.sciencemag.org/content/early/2020/05/19/science.abc4776
“ We developed a rhesus macaque model of SARS-CoV-2 infection and observed that macaques had high viral loads in the upper and lower respiratory tract, humoral and cellular immune responses, and pathologic evidence of viral pneumonia. Following initial viral clearance, animals were rechallenged with SARS-CoV-2 and showed 5 log10 reductions in median viral loads in bronchoalveolar lavage and nasal mucosa compared with primary infection. Anamnestic immune responses following rechallenge suggested that protection was mediated by immunologic control. These data show that SARS-CoV-2 infection induced protective immunity against re-exposure in nonhuman primates.”