Federal spending on COVID-19 vaccine candidates tops $9B

The federal government has allocated more than $9 billion to develop and manufacture candidate vaccines. More than $2.5 billion more has been ear marked for vials to store the vaccines, syringes to deliver them, and on efforts to ramp up manufacturing and capacity. And they're not done yet. So far, the largest sums have gone to pharmaceutical giants Pfizer, AstraZeneca, and a collaboration between Sanofi and GSK, as well as biotech firms Moderna and Novavax – all of which have candidate vaccines being tested in people.

To save time in the development process, the companies have been running trials simultaneously that they usually run in sequence.

Modern a, for instance, hasn't yet published its phase 2 trial results, but is already in larger-scale phase 3 trials, beginning tests last week of its candidate vaccine in 15,000 volunteers. Phase 3 trials started this summer are expected to return results this fall, with the timing depending on how quickly they can find volunteers.

None of t he candidate vaccines use the whole virus, so they cannot cause COVID-19. Instead, they train the immune system to respond to the virus' spike protein – which gives the coronavirus its distinctive shape. Once the immune system is trained to recognize the spike protein, it should be able to rapidly clear the virus should the person be exposed again.

The vaccine candidates now receiving government funding are all based on new technologies, most of which have not been the basis of previously approved vaccines. They have been chosen because they were faster to develop than more conventional vaccines, which is important in fighting a virus currently killing about 1,000 Americans a day.

If any of these approaches prove safe and effective, it could transform vaccine development worldwide, allowing faster attack strategies against dangerous viruses that may emerge in the future, as well as those that mutate rapidly, like the flu.

Almost all the candidate vaccines in human trials will require two doses to become fully effective, which means many hundreds of millions of doses will be needed to vaccinate the majority of America's 328 million residents.

It is not known exactly what percentage of a population must be vaccinated to provide enough “herd immunity” to stop or prevent an outbreak, but researchers believe at least 50%-70% of the population will need protection.

To win government approval, all the candidate vaccines have to go through three phases of testing in people, starting small to prove basic safety, and ending in 30,000-person trials, where half the volunteers get a placebo and half get an active vaccine. This stage proves the vaccine will be safe for the vast majority of people who get it, though rare reactions can still occur.

In each of the phase 3 trials, only about 150-160 people will have to fall ill with COVID-19 for statisticians to be able to calculate the effectiveness of the vaccine.