in

With two shots on the horizon, here’s what to know

As the pandemic covers an ever-widening swath of the country, Moderna’s announcement that its COVID-19 vaccine would be 95% effective according to preliminary data offered Americans a much-needed shot of hope.

It was the second time in two weeks that independent safety monitors examined data from clinical trials and determined that the experimental vaccine performed above expectations. Last week, Pfizer, in collaboration with its German partner BioNTech, also claimed that its vaccine was 90% effective in preventing symptoms of the disease.

“The light at the end of the tunnel is getting a little brighter,” said Dr. William Schaffner, an infectious disease and preventive medicine expert at Vanderbilt University.

The news comes as multiple states issue new lockdown orders to halt a third wave of coronavirus infections. Last week alone, more than a million new cases were recorded, and more than 1,100 Americans die every day.

Pfizer and Moderna have yet to release detailed data from this final stage of clinical trials, and results may change when complete. But many experts are optimistic that the initial distribution of these vaccines could begin by the end of the year.

“The results from Pfizer, and now Moderna, are very encouraging to me,” acknowledged Dr. Buddy Creech, director of the vaccine research program at Vanderbilt University Medical Center. “Efficacy levels exceed our expectations, which gives us strong hope that we will see an end to the pandemic when widespread vaccination becomes possible.”

Here’s a closer look at the situation with these early vaccines.

What does it mean for a vaccine to be 90% or 95% effective?

Clinical trials measure how good experimental vaccines are at reducing a person’s risk of becoming infected with the coronavirus that causes COVID-19.

To do this, the researchers recruited volunteers who received two doses of the vaccine or a placebo, without knowing which was which. They were then encouraged to continue with their daily activities.

The trials included an evaluation after a predetermined number of volunteers contracted COVID-19. Moderna, for example, enrolled 30,000 participants and planned to cease after 151 cases were recorded.

So far, 95 people have become ill, which was enough for the data monitoring board to provide an early assessment of the vaccine’s efficacy. Participants will continue to be evaluated to see how immunization works over time.

The conclusion was that after three months of exposure in typical communities across the country, about 29,900 subjects in Moderna’s trial remained symptom-free. Of the 95 who became ill with COVID-19, 90 were in the placebo group and five had been vaccinated.

This information allowed the review board to conclude that the vaccine is 94.5% effective. The data is still being evaluated to determine why 5% of those inoculated became ill.

The numbers are similar to the Pfizer trial, which enrolled 44,000 people. However, unlike Moderna, Pfizer did not provide information on the severity of the disease among the participants.

“The surprising and hopeful news is that the vaccine had a significant and positive effect in reducing disease,” said Dr. Larry Steinman, professor of pediatrics and neurological sciences at Stanford University, who led the department’s program of immunology for a decade.

Why aren’t all volunteers getting the vaccine?

Researchers need something to compare their vaccine against to assess whether it is better or worse than doing nothing. In this case, the placebo is simply a saline solution.

But it’s not just the participants who don’t know if they received the experimental treatment or the placebo. The researchers who examine them also ignore it. In this way, when they evaluate the health of a volunteer, they are not influenced by the knowledge that the volunteer received the experimental vaccine or not.

“Placebo-controlled trials are the best way to remove bias from the equation,” said Vanderbilt’s Creech. “They allow us to see how well a vaccine works. Assigning randomly and remaining ‘blind’ as to what a volunteer received allows a better judgment of whether the vaccine works. “

The study design also helps researchers identify side effects caused by the vaccine. For example, if those who received the placebo complained of pain in their arms as much as those who received the vaccine, it would be reasonable to conclude that this is a result of the needle and not necessarily due to the active ingredients of the compound.

If the results are so good, why do they keep trying the vaccine?

It takes more time for more study participants to get sick. The more cases there are, the more researchers will notice that the results of the two groups of volunteers are different and that the vaccine works better than the placebo.

Some side effects can also take time to develop, and the test should last long enough for them to have a chance to appear.

In general, clinical trials can stop earlier than scheduled if early data make it clear that an experimental drug is completely ineffective, or when the results are so favorable that it is no longer ethically responsible to deny it to those who received the placebo.

What side effects have been seen so far?

All have been minimal. Some participants reported arm pain for a day or two. Others complained of headaches and fatigue, as well as general muscle aches. Neither of these is considered a serious adverse reaction.

Even trials of this size might not be able to detect very rare adverse events, which is why even after a vaccine is approved, monitoring systems continue to look for rare events in the general population.

When will the final results of the Moderna and Pfizer vaccines be?

These clinical trials were designed as two-year studies, so it is unclear when the final results will be available. However, these are necessary for the Food and Drug Administration (FDA), which is tasked with examining new remedies for public use, to decide whether to grant emergency use authorization to any COVID-19 vaccine and allow make it available to the public. If such authorization is granted, the vaccines could begin to be distributed in December.

Are other candidates currently being tested?

The vaccines being developed by AstraZeneca and Johnson & Johnson are also considered viable contenders.

Both labs are in the last stages of their clinical trials, and enrollment continues around the world. These vaccines are made slightly differently from Pfizer and Moderna, but because they attack the same protein on the surface of the virus, “we are very confident that they could enjoy similar efficacy,” Creech said.

How soon can I get vaccinated?

If the FDA issues an emergency use authorization, the Centers for Disease Control and Prevention (CDC) will be in charge of overseeing the distribution of the vaccine to the public. States will also develop their own plans. While there is still a lot of uncertainty, it is already clear that initially there will not be enough doses for everyone.

Early prioritization schemes put healthcare workers at the front of the line. They will be joined by older people and people with underlying medical conditions, because those groups are more likely to become seriously ill if infected.

Both Pfizer and Moderna have publicly reported that they will have about 20 million doses by the end of the year, but experts believe it will take until late spring or early summer to produce enough doses to immunize most US residents. USA

In any case, specialists emphasize that public health protocols, such as the use of masks and maintaining social distance, should remain in force for months or even years after vaccines are available for the first time.

What remains to be answered is whether these vaccines will prevent people from getting infected. As promising as these trials are, it is not known whether the vaccine will stop the spread of the virus.

To read this note in Spanish, click here