Dan Barouch, MD, PhD (Center for Virology and Vaccine Research, BIDMC) discusses the recently released interim analysis of Pfizer’s COVID-19 vaccine candidate.

Boston 25 – November 10, 2020

Pfizer vaccine candidate praised even by competition

BOSTON — At the Center for Virology and Vaccine Research at Beth Israel Deaconess Medical Center, Dr. Dan Barouch called the interim analysis of Pfizer’s COVID-19 vaccine candidate “stunning.”

“I don’t think that many of us anticipated an efficacy of 90%,” Dr. Barouch said. “So this is truly a triumph of science.”

Dr. Barouch’s generous praise came even though he is working with Johnson & Johnson on another COVID-19 vaccine.

“This is not a race of one company versus another or one product versus another,” he said. “This is a race against the pandemic. Particularly given the explosion of the pandemic in recent weeks that we have seen throughout the United States.”

U.S. cases exceeded 10 million this week and deaths are approaching 240,000. Daily cases nationally have topped 100,000 several times.

In Massachusetts, three recent days saw more than 2,000 daily cases, and hospital admission rates for COVID-19 are climbing so fast Gov. Charlie Baker is talking about the return of those field hospitals from spring.

“What we actually need is multiple vaccines,” Dr. Barouch said.

Both the Johnson & Johnson and Pfizer products work in novel ways. Pfizer’s uses messenger RNA technology, also known as mRNA.

“The idea of mRNA vaccines has been around for about 20 or 30 years,” said Dr. Marc Siedner, a researcher at Massachusetts General Hospital. “Many other vaccines are viruses that have been changed to not make you sick but to make your body think that they’re the virus. This is basically using our own cellular machinery to make proteins that look like the virus.”

The Johnson & Johnson product delivers part of the virus to cells using an adenovirus vector.

“For the adenovirus vaccine, the COVID-19 nucleic acid is encoded within a deactivated common cold virus that is very efficient at getting into cells,” Dr. Barouch said. “So basically they’re two different methods of getting COVID 19 spike protein nucleic acid into cells.”

Once inside the cells, the spike protein is manufactured and then the body makes an antibody against it.

“None of these vaccines that are being tested in the United States ever started off as a full virus particle,” Dr. Barouch said. “So there is no chance that any of these vaccines will actually cause COVID-19 disease.”

One advantage of technologically-advanced vaccines is that they are easier to manufacture.

“Many vaccines, especially things like influenza and others, are quite complex to make,” Dr. Siedner said. “They require embryonic chicken eggs, growth over months of time.”

By contrast, manufacture of an mRNA vaccine could be done in a matter of weeks, an important factor when considering the number of doses the world will need.

One disadvantage to the Pfizer candidate is the storage it requires: a super-cold environment of -80 degrees Celsius.

“So I think Pfizer and others are working on technologies that’s going to allow them to be distributed in these cold packages that will allow them to stay at very cold temperatures for long periods of time,” Dr. Siedner said.

Obviously, many obstacles remain to getting a COVID-19 vaccine to the general public. Dr. Siedner said with the Pfizer candidate, more safety data is needed as well as information on whether it can prevent the kind of severe infections that require hospitalizations.

Another important piece of missing data: how long the immunity lasts.

So, at a time when the entire world has had it with COVID-19, doctors, researchers and regulators are asking the public for the one thing in short supply: patience.

“When a company announces efficacy data, that’s not the day that anyone can go to their local pharmacy or doctor and get the vaccine,” Dr. Barouch said.

“This is not the last we’re going to hear about this and we need to be patient and wait for the final results to come out but certainly what we’ve seen so far has been very promising,” Dr. Siedner added.