Fast-track tests of 26 potential coronavirus vaccines are underway in our country, as well as in Britain, Brazil and South Africa. U.S. researchers recently began enrolling around 30,000 volunteers for final-stage tests of a vaccine from a company named Moderna. Pfizer and AstraZeneca, two other leading drug makers, also are doing patient trials. Others start regularly. The federal government helps finance and coordinate these studies of effectiveness and safety in a effort called Operation Warp Speed. It has set an ambitious "goal of delivering 300 million doses of a safe, effective vaccine by January," posts the Department of Health and Human Services. Officials also need to make sure doctors, drugstores and state health departments have enough vials, needles and syringes for millions of adults and young people.

The best hope, naturally, is for several vaccines that protect people from the potentially deadly Covid-19 virus. That's a longshot, partly because as the disease spread into a global pandemic (pronounced pan-demm-ICK) it evolved into different types that may require different approaches. "Some Covid-19 vaccines may not prevent infection entirely, but they could still prepare a person's immune system so that, if infected, they would experience milder symptoms, or even none at all," says University of Florida specialist Natalie Dean. That's similar to the flu vaccine: It's not perfect, but we advise people to get it because it reduces intensive care admissions and deaths."

Some medical experts warn against expecting too much too soon. "I am concerned a vaccine might be rushed to the marketplace," says Dr. Howard Markel, medical historian at the University of Michigan. "The very name of the project -- Warp Speed. It's probably never a good idea to name your vaccine project after something from Star Trek." Dr. Anthony Fauci, a White House adviser and longtime specialist at the National Institutes of Health, notes that while a vaccine could be approved this year, it likely won't be offered on a large scale until February or spring. "I think as we get into 2021, several months in, that you would have [a] vaccine that would be widely available to people in the United States," explains Fauci. His boss, institutes director Dr. Francis Collins, puts it this way: "Sooner would be better, but it's not going to get tied to any other timetables, other than making sure we've got something that works and it's safe."

President Trump says: "We're balancing speed and safety and we're on pace to have a vaccine available this year, maybe far in advance of the end of the year. And we're mass-producing the most promising candidates in advance so that we're ready upon approval." – At White House briefing Aug. 3

Professor says: "Evidence that would convince me to get a Covid-19 vaccine, or to recommend that my loved ones get vaccinated, does not yet exist." – Natalie Dean, University of Florida assistant professor of biostatistics

Economist says: "Our baseline expectation is that a large number of vaccines eventually gain approval, with at least one FDA approval this year." -- Daan Struyven, senior economist at Goldman Sach, in Aug. 3 report to investors