Coronavirus vaccine timeline: We could know if a shot works before election

US President Donald Trump is making lofty claims about the potential for a coronavirus vaccine before the November elections.

On Thursday, he said a vaccine could be ready “right around” the November 3 contest. Earlier in the week, he said a shot could be available “far in advance of the end of the year.”

An effective coronavirus vaccine would be a huge step toward curbing the pandemic and helping people in the US get back to work. Plus, some of Trump’s advisers think having a vaccine is essential for the president’s reelection prospects, as the Associated Press reported.

Read more: There are more than 160 research programs hunting for a coronavirus vaccine. Here’s how the top drugmakers see the race for a cure playing out and when the first shots might be available.

To be clear, it’s very unlikely that there will be a widely available coronavirus vaccine before the end of the year. The Trump administration’s own vaccine effort, called Operation Warp Speed, has said that its goal is to have 300 million doses of a vaccine available in January. Most of these experimental shots are two-dose regimens, which further strains supply.

We could get crucial coronavirus-vaccine data in October

But it’s possible that in October, we could get data showing that one or more experimental vaccines works to prevent the coronavirus or the disease it causes, COVID-19. The biotech company Moderna, for instance, has said that we could know whether its vaccine works as soon as October, and Pfizer has said it could have data ready to show to US regulators that month as well, for a vaccine its created with the biotech BioNTech.

Based on that data, regulators at the Food and Drug Administration could decide to let some people at high risk for catching the disease, such as healthcare workers, get the shot. That might be just enough good news for Trump to declare vaccine victory and deliver an October surprise.

Read more: Moderna’s CEO shared a detailed timeline for when we’ll know if its coronavirus vaccine works, and cautions that you might not get a shot until the spring

Biotech analysts at Morgan Stanley laid out how that could happen in more detail in a recent note to investors. To be sure, they think it’s more likely that we’ll get conclusive data on vaccines from late-stage trials in people in November.

There’s a narrow window for an October surprise

The potential for an October surprise hinges on how these trials are designed. Each trial involves about 30,000 volunteers, half who get a coronavirus vaccine, and half who don’t. Over time, researchers watch to see how many people in each group get sick from the coronavirus.

Once a certain number of people get sick, the researchers run calculations to see whether the vaccine has helped or not. In at least Moderna’s trials, the researchers take a look at the data several times over the course of the study. Since these data checks are based on how many people get sick, it’s impossible to say for sure when they’ll happen.

Read more: TIMELINE: Morgan Stanley says we should know if a coronavirus vaccine works by November. Here’s how the bank expects the race for a cure to play out.

But by analyzing the rate of coronavirus spread and several other factor, the analysts at Morgan Stanley created detailed timelines for the vaccine trials. They show that narrow window for an October surprise. We’ve annotated the timelines to show the most important part.

The Morgan Stanley analysts didn’t provide a detailed timeline for the third leading vaccine effort, from AstraZeneca and researchers at University of Oxford. They said they think we could get data from that effort on a similar timeline to Pfizer and Moderna.

The Moderna timeline:

Morgan Stanley

The Pfizer-BioNTech timeline:

Morgan Stanley

Eliza Relman contributed reporting.