A researcher works on the development of a vaccine against the new coronavirus. Photo: AFP and South China Morning Post

This article discusses “immune enhancement”:

News Feature: Avoiding Pitfalls In The Pursuit Of A Covid-19 Vaccine, PNAS, 14 April 2020

As they race to devise a vaccine, researchers are trying to ensure that their candidates don’t spur a counterproductive, even dangerous, immune system reaction known as immune enhancement.

Researchers need to understand in particular whether the vaccine causes the same types of immune system malfunctions that have been observed in past vaccine development. Since the 1960s, tests of vaccine candidates for diseases such as dengue, respiratory syncytial virus (RSV), and severe acute respiratory syndrome (SARS) have shown a paradoxical phenomenon: Some animals or people who received the vaccine and were later exposed to the virus developed more severe disease than those who had not been vaccinated (1).

No matter how urgent it is to get a vaccine out, it has to be tested for safety and of course effectiveness … on animals, on healthy humans, and on humans who aren’t so healthy, which includes many older adults, a group at highest risk for dying from COVID-19. Takes time.

Another Truth Void:

President Trump on 2 March 2020: Pharmaceutical companies are going “to have vaccines, I think, relatively soon.”

The Atlantic: The president’s own experts told him during a White House meeting with pharmaceutical leaders earlier that same day that a vaccine could take a year to 18 months to develop. In response, he said he would prefer if it took only a few months. He later claimed, at a campaign rally in Charlotte, North Carolina, that a vaccine would be ready “soon.”
All the President’s Lies About the Coronavirus, The Atlantic, 9 April 2020