Cambridge University Immunologist Answers Key Questions About the Pfizer Vaccine

In a recent podcast from BBC Radio's Chris Smith from The Naked Scientist interviewed immunologist Claire Bryant from Cambridge Univerisity. Together, they discussed the vaccine candidate developed by Pfizer and BioNTech who released the first interim analysis of phase three clinical trials earlier this month.

Claire Bryant described the vaccine candidate as "very interesting" because of the new technology used. The genetic material code of virus spike protein is packaged "up into an oily droplet," which is injected into the volunteers. After the genetic material enters the body, cells "make the virus spike protein, and then an immune response against this is generated."

This specific type of vaccine is also relatively cheap and can be made quickly, which is ideal for mass distribution. However, said Bryant, since it is new and untried only the phase three trials can reveal if it is safe and efficient.

Pfizer's Clinical Trials

For the first time in a while, said Smith, there was some good news about the current pandemic. The vaccine candidate, known as BNT162b2, showed an efficacy rate of about 90% a week after the second dose was administered, according to Pfizer's press release. "What does that actually mean?" asked Smith.

It means that 10% did get infected, explained Bryant which comes with important questions such as who the infected are like their age group of other factors. More importantly, did they develop severe coronavirus after infection or belonged to a high-risk group? Despite these questions, the 90% success rate is still "potentially good news."

According to Pfizer, phase three of clinical trials began in July with more than 43,500 participants. Over 38,900 received a second dose of the vaccine on November 8. 30% of participants are from the United States and have racially and ethnically diverse backgrounds.

Since the data has not been released yet and needs to be peer-reviewed, "it's hard to judge just how important this step forward actually is," continued Bryant. Only the data can reveal who was and wasn't protected. Other important factors include how long immunity will last and if the vaccine can effectively protect older people.

Side Effects and Vaccine Availability

When asked if the company peaked too soon by announcing at this time, Bryant responded that perhaps it would have been better than the data was published simultaneously. "It would be interesting to understand the rationale for releasing that information quite so early," she said.

Bryant then discussed the side effects, which are typical of vaccine shots. Side effects such as lethargy is a result of the body responding to the virus and not because the body has a viral infection.

The key question, said Smith, is when will the average person have access to a vaccine. Bryant said that higher-risk groups, health workers, and other front liners may likely be vaccinated by next spring. The rest may have access by summertime, Bryant guesses.

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