A Covid-19 Vaccine Shows Encouraging Signs
Developed by Pfizer and BioNTech, an experimental vaccine spurred immune responses in a small trial of humans
An experimental vaccine being developed by pharmaceutical giant Pfizer and German firm BioNTech appears safe and produced encouraging immune responses in a small trial of healthy volunteers, according to results published online Wednesday.
The study included 45 adults ages 18 to 55. Researchers randomly gave the people in the study a low, medium, or high dose of the vaccine or a placebo. Those who received a low or medium dose got a second dose three weeks later. Half of the 12 people who received the high dose developed a fever, including one person whose fever was severe. Those people were not given a second dose of the vaccine.
In 24 people who received the low or medium dose, the vaccine triggered an immune response similar to or stronger than those who have recovered from Covid-19 infections. Specifically, two doses of the vaccine produced antibodies — proteins made by the immune system in response to a foreign pathogen or vaccine. Notably, the second dose boosted the level of so-called “neutralizing” antibodies capable of blocking infection.
In those who received two doses of the vaccine, researchers detected levels of neutralizing antibodies at or above levels that have been found in blood plasma from Covid-19 survivors. There were no serious or life-threatening side effects.
Neutralizing antibodies are believed to be linked to immunity against the virus, but researchers will need to test vaccines in much larger studies to know for sure. Scientists will need to show that people who receive a vaccine are less likely to become infected with the coronavirus, and that will require vaccinating thousands of trial participants.
Pfizer and BioNTech published the preliminary results on MedXriv, a preprint server for scientific papers. The study is currently undergoing scientific peer-review for potential publication according to a press release issued by the companies.
“It’s the first positive data I’ve seen coming out of Operation Warp Speed,” Peter Hotez, MD, PhD, dean for the National School of Tropical Medicine at Baylor College of Medicine, told the Washington Post.
Announced by the Trump administration on May 15, Operation Warp Speed is the U.S. government’s ambitious plan to make an effective Covid-19 vaccine available to Americans by January. Pfizer, along with drugmakers AstraZeneca, Merck, Johnson & Johnson, and Moderna, have reportedly been chosen by the administration as the most likely companies to deliver a vaccine in that timeframe, according to the New York Times.
Pfizer and BioNTech are evaluating a total of four experimental Covid-19 vaccines. Early results will help determine the design of the next trial, which will include up to 30,000 healthy participants and begin by the end of July at the earliest. If one of their vaccines ends up being effective, the companies say they expect to manufacture up to 100 million doses by the end of 2020 and potentially more than 1.2 billion doses by the end of 2021.
Moderna, another frontrunner in the race, has not formally published any data but issued a press release on May 18 that provided a first glimpse of its vaccine’s effects in people. The company said the vaccine looks safe and produced antibodies in 45 people aged 18 to 55 but provided few other details. On June 11, the company announced that it would begin testing the vaccine in a larger trial of 300 people.
Moderna’s vaccine, as well as the ones being developed by Pfizer and BioNTech, are so-called RNA vaccines. They contain a short segment of genetic material, called messenger RNA, which tells human cells to make a particular protein found on the coronavirus. The presence of this protein kicks off an immune response in the body. The technology is still unproven though, and there are no RNA vaccines on the market yet.
Overall, more than 150 experimental vaccines for Covid-19 are currently in development, according to the Milken Institute, an economic think tank based in Santa Monica, California. But developing an effective vaccine is just the first step. In order to establish herd immunity — the threshold that makes it difficult for the disease to spread — pharma companies will need to be able to manufacture millions of doses, and public health officials will need to figure out how to distribute a vaccine as far and wide as possible.