There are promising signs in the race to come up with a COVID-19 vaccine and to understand if humans can be immune after recovering from infection.
Two studies published on Wednesday offered the first scientific evidence that reinfection may not be possible.
In one study, monkeys who were infected by researchers with the novel coronavirus and recovered did not get sick again once exposed to the virus.
In the second study, 25 monkeys were given prototype vaccines and 10 other animals were not; after both groups were exposed to a coronavirus related to SARS, all of the animals not vaccinated came down with the virus, while the vaccinated monkeys saw some measure of protection. In fact, 8 of the 25 monkeys were totally protected.
While both results were promising and suggest the search for a vaccine is on the right track, scientists caution that they still don't prove humans can develop immunity and if they do - how long it lasts.
There are currently no approved treatments or vaccines for COVID-19 and experts predict a safe and effective vaccine could take up to 18 months to develop.
But there is a race to shorten that window.
Inovio Pharmaceuticals, a U.S.-based immunotherapy company, announced Wednesday its experimental treatment produced protective antibodies and immune system responses in mice and guinea pigs.
Its vaccine builds on a potential treatment Inovio was already working on for a different, but related coronavirus that causes Middle East Respiratory Syndrome.
Both treatments are made using newer technology that focuses on specific genes.
Trials on 40 humans began in April and preliminary results are expected next month. Approval would then be needed from the Food and Drug Administration to conduct more-advanced human trials. That could happen as early as July or August.
Last week, President Trump announced the U.S. government would invest in all potential vaccines in hopes of getting a treatment on the market by the end of this year.