Pfizer reports encouraging early COVID-19 vaccine data

An experimental vaccine being developed by pharmaceutical giant Pfizer and the German firm BioNTech triggered stronger immune responses in recipients than what was seen in people recovering from a natural infection in a small study, published online Wednesday.

The work has not yet been peer-reviewed, and it is still unclear what level of immune response will protect a person from getting sick. But outside scientists praised the company for publishing the data on 45 patients and said the results support moving to a larger clinical trial that can test whether the vaccine is safe and effective.

“It’s the first positive data I’ve seen coming out of Operation Warp Speed,” said Peter Jay Hotez, dean for the National School of Tropical Medicine at Baylor College of Medicine. “I’m really happy Pfizer took the initiative to publish it, whereas the others haven’t. I think we need to see more of this.”

Hotez said that the key data the company shared was a boost in the level of antibodies capable of neutralizing the virus after the second dose of the vaccine was given. Those antibodies increased to levels greater than those seen in the blood plasma of patients who have recovered from COVID-19.

The biotechnology company Moderna gave a glimpse of its early data through a news release in May and is expected to begin its large clinical trial this month, but has yet to share full results from its initial safety study, which will be published by scientists at the National Institutes of Health.

Inovio Pharmaceuticals, a company working on a DNA vaccine also announced positive results via news release this week. The incomplete data have frustrated scientists trying to evaluate the different approaches.

There was a concerning signal in the Pfizer trial that, scientists said, will have to be closely monitored when the vaccine is tested in a broader population: The majority of people given an intermediate dose of the vaccine developed fevers, chills and other low-grade symptoms that lasted a day.

But other vaccines that cause people to feel bad, such as the shingles vaccine Shingrix, have tremendous value because of their benefits, and the same could be true with a COVID-19 vaccine if it is shown effective.

“With Shingrix, you miss a day of work. On the other hand, you’re preventing one of the worst pains in medicine, associated with shingles,” said Paul Offit, director of the Vaccine Education Center at the Children’s Hospital of Philadelphia. “I think the same thing is true here: You’re willing to suffer a day or two knowing you have the chance not to be infected.”

Pfizer and its partner, BioNTech, are testing four vaccine candidates, all based on a technology platform that delivers RNA, genetic material that triggers the body’s own cells to turn into vaccine factories. The results are from one of the candidates, and the company said in a statement that it plans to use the data to select a dose and candidate to proceed to a large, 30,000-person trial that could begin at the end of the month with regulatory approval.