Three potential vaccines for COVID-19 have shown good results in early studies.

Despite different mechanisms of action, all three induced an immune response in participants. The most advanced of the three – a vaccine candidate from the British drugmaker AstraZeneca – also seems to induce the body to make T cells – a second part of the immune system that could be important for a lasting immune response.

None of these potential vaccines has shown serious side effects that could stop their testing, but they must still prove they’re both safe and effective when tested on thousands of subjects, including those at high-risk for severe COVID-19.

We still have a long way to go. Remember, historically, just 6 percent of vaccine candidates end up being used on patients. Hopefully, a COVID-19 vaccine will make it.