The arrival of Pfizer’s first results out of their phase 3 trial just six days after the election was not a conspiracy—it was right on schedule for the timeline Pfizer and partner BioNTech laid out when they announced their phase 3 testing in July. Likewise, the results announced on Monday from Moderna’s first interim analysis of phase 3 data is also coming in right on time, if not slightly ahead of when they were expected.
The fact that both of these companies are currently showing efficacy above 90% is fantastic. However, that doesn’t mean that it’s time to head to your local clinic and line up for a shot. There are still a large number of unanswered questions that aren’t covered by the single numbers that have been appearing in headlines. Those questions absolutely have to be answered before either of these vaccines can go into distribution—and there are reasons why both companies are being very fast to push out some information, and very slow to provide the rest.
How effective are these vaccines in the elderly? How effective are they in children? Are they safe for women who are pregnant? The simplest reason why both Pfizer and Moderna have failed to provide most of these answers so far is this: They don’t know. Both companies recruited tens of thousands of volunteers to take part in their trials, with both the first groups setting down for the start of the first jab of the two-dose treatments around the start of August. But filling out those ranks of volunteers, at locations across the county as well as in other locations around the world, took weeks.
Both companies are now reporting on the results from fewer than 100 cases of COVID-19 … though it’s not actually correct to say that they’re looking at only 100 patients. When the trials were established, both companies used mathematical analysis to determine the points at which these first interim results would be calculated. For example, Moderna set that number at 95 cases. Essentially, they waited until 95 people caught COVID-19, then they opened the sealed data on those patients, looked inside, and determined that 90 cases came from those volunteers who received a placebo, while five came in the group that received the actual vaccine.
When Moderna says that their vaccine was 94.5% effective at this point, that’s what they mean—90 out of the first 95 patients in the study to catch COVID-19 came from the placebo group.
However, there are roughly 15,000 patients in Moderna’s placebo group. So only 0.6% of that group has so far tested positive—meaning that the rate of infection within the group is only about one-sixth the average infection rate in the United States. That’s not because the placebo shot also provided some mysterious protection. It’s also hopefully not because people getting the placebo have been doing a much better job of social distancing than the average American (let’s hope, because that could really skew results). It’s just a matter of time. Most of those people in both Pfizer and Moderna’s trial have only been there for a few weeks. Since they all went in uninfected, 0.6% is just the percentage that have become ill over that period. On the other hand, only 0.03% of the people who got the vaccine have become sick over that period. Which sounds good. Also really good: all the severe cases of COVID-19 in the Moderna test were in the placebo group. Among the few who caught the disease from the vaccine group, no one had more than a mild case.
Go ahead. Get excited. Because the results of these tests aren’t just good for Pfizer and Moderna, they’re also good for other manufacturers like AstraZeneca and Johnson & Johnson, whose vaccines target the same proteins. But do recognize that, with data sets this small, the genuine results really could be quite different. Differences in health, in behavior, in sheer coincidence, might significantly alter the numbers we've seen at this point.
There are also reasons why both Pfizer and Moderna are in a big damn hurry to get good news over the line quickly. Both companies are depending on an entirely new type of vaccine using messenger RNA (mRNA). This is a potentially huge technological change that could make future vaccines faster and more reliable. It’s also something that has never previously been tested in human beings, and which—barring something like, oh, a global pandemic—might have been another decade or more gaining approval even for human trials.
For Pfizer, getting approval on this vaccine would crack open a multibillion dollar potential for their partnership with BioNTech and open the way for vaccines on things that might not even seem vaccinable — like several forms of cancer. For Moderna, this is literally the ballgame. They are all in on this vaccine, and if it doesn’t turn out to be a win, the possibility of their company completely folding is extremely high. This doesn’t mean that either company is fudging data or cutting corners. It does mean that both have extraordinary incentives to get good news out in a hurry, and give any potential bad news … additional study. So keep that in mind.
Within the next two to three weeks, it’s likely that we’ll be seeing additional data from both the companies that helps to address remaining safety concerns as well as providing additional details about those who have become ill. The longer these trials go on, the more informative the results will be. Also expect to see additional results soon from the Oxford/AstraZenca vaccine in which testing was delayed, especially in the U.S., when one volunteer developed an illness that is now thought to be unrelated to the vaccine.
Around that same time, first results may also come in from Johnson & Johnson. They were considerably later in starting enrollment for their phase 3 trials, but they have a secret weapon: their vaccine involves only a single dose. They essentially steal a month back from the other guys with vaccines that involve two doses delivered four weeks apart.
Everything we’ve seen so far from vaccine trials looks good. Seriously good. There’s every reason to be cautious, but no real reason to be suspicious of those results. Still, a few more weeks should really fill in the blanks … and let everyone start planning for when they can visit their local pharmacy for their first jab.
Author’s note: The usual warnings apply. I am not a doctor. Don’t make healthcare decisions based on anything I’ve written. Please consult with your own doctor or health professional. And also, wear a mask, dammit.