A Covid-19 Vaccine Shows Encouraging Signs

Developed by Pfizer and BioNTech, an experimental vaccine spurred immune responses in a small trial of humans

Emily Mullin
Medium Coronavirus Blog
3 min readJul 1, 2020

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Credit: Science Photo Library/Getty Images

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…

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Emily Mullin
Medium Coronavirus Blog

Former staff writer at Medium, where I covered biotech, genetics, and Covid-19 for OneZero, Future Human, Elemental, and the Coronavirus Blog.