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There’s a lot to celebrate about Pfizer and BioNTech’s new Covid-19 vaccine which, reported last week, offers more than 90 percent protection in early data.
The vaccine trial has found no “serious safety concerns” so far and is in the final stage of testing, known as a phase 3 trial. It may be available to a limited number of people by the end of the year.
News of its success rate was greeted with jubilation around the world and hailed as “a victory for innovation and a global collaborative effort” by Professor Ugur Sahin, BioNTech co-founder and CEO.
But for vaccines to work, people must be willing to take them (it is believed that an absorption of at least 55%, and probably more, is needed to achieve herd immunity), and after a tumultuous year, there are signs that some doubt.
Here, three medical experts answer some common questions about the vaccine.
Are:
- Trudie Lang, Professor of Global Health Research at Oxford University, who works on malaria vaccine development and served on the Ebola vaccine safety board
- Heidi Larson, Professor of Anthropology, Risk and Decision Science at the London School of Hygiene and Tropical Medicine and Director of The Vaccine Confidence Project
- Dr. Michael Fitzpatrick, GP and author of MMR and autism: what parents need to know
How can we be sure that the vaccine is safe, when it has been tested for such a short time?
Lang: The vaccine development pathways are well defined and each vaccine must follow the same pathway and meet the same standards. Although it has been incredibly fast, there will definitely be no shortcuts. The biggest change is how well science collaborates and works as a collective organization. With the Covid vaccine, we got off to a very good start because the genetic code was shared very quickly and the technology has already been used in cancer therapy.
And a key factor in how quickly we have learned whether or not it works is the level of infection in the community, especially in the second wave, where there is a lot of transmission.
This trial involved 43,538 people of various backgrounds (half of whom received the vaccine, while the rest received a placebo). That is a good number to bring the required security data.
Larson: New scientific technology and funds available after the Ebola outbreak have accelerated the process.
There are extremely stringent security measures around these trials. Some companies have come together and signed an agreement that says they will not be pushed around by political processes.
This is an mRNA vaccine, a technology never used before for a virus, so should we have a longer trial period?
Lang: MRNA technology has been used in cancer therapy, so we are building on what we already know. This vaccine delivers a code that instructs human cells to build copies of the protein spikes on the surface of the Covid-19 virus.
Then our bodies produce antibodies against these protein spikes and this allows the body to respond to an actual infection.
The code can only produce this specific protein and do nothing else. It cannot insert into our DNA, it cannot replicate, and it is not infectious.
Regardless of technology and urgency, it will follow the same steps as any vaccine. During the trial, there will be a review committee of independent experts who are not part of the trial, or the pharmaceutical company and, in addition to that, there are the regulators.
Fitzpatrick: MRNA is in many respects a cleaner technology than traditional vaccines, when an existing strain of the virus is modified to reduce its virulence.
Could the vaccine have unpredictable, yet undiscovered side effects?
Fitzpatrick: The answer to that is honestly yes. But most vaccines produce adverse side effects fairly quickly. The most recent serious problem was the swine flu vaccine that caused rare cases of narcolepsy, but they appeared a few weeks instead of six months later. I can’t think of a very long-term side effect from a vaccine.
Lang: Regulators aren’t going to approve anything they don’t think is absolutely safe, and then when it goes mainstream, there’s a really strong oversight process to keep collecting safety data.
Larson: There may be side effects that show up in a particular individual, even after hundreds of thousands of people have received the vaccine, but that would be rare. Anything more common would appear before the vaccine was made public.
Has the vaccine been tested in people over 70 or other vulnerable groups?
Fitzpatrick: The Pfizer vaccine has been tested in people ages 12 to 85 and also in ethnic minority groups and blacks.
In older age groups, vaccination is always an uncertainty because their immune system tends to respond less. It could be that they don’t get a response or are more affected by side effects.
The phase 3 trial also included people with chronic stable HIV, hepatitis C, and hepatitis B. It will be tested in other populations once the phase 3 trials are completed.
Lang: The MHRA (Medicines and Health Products Regulatory Agency) will absolutely want to see safety data for all age groups that will receive the vaccine and will wait for data on ethnicity and underlying disease. Regulators will only approve the vaccine for groups where they have the data.
Will the children have it? Aren’t your immune systems too immature?
Lang: If they were to vaccinate children, they would have to do a full pediatric testing program and since children don’t really get sick, I would only vaccinate them to prevent transmission in the community.
Fitzpatrick: As far as I know, there are no plans to vaccinate the children at the moment.
I don’t think it’s a matter of maturity of the immune system. Children’s immune systems are quite active, so we give babies vaccinations.
It’s more a question of logistics and the relative impact of the disease. One of the few positive things about the coronavirus is that it does not affect children as much as adults.
Shouldn’t we wait for a vaccine that is 100% effective?
Larson: No. It is extremely rare for any vaccine to be 100% effective; 90% is already high.
Fitzpatrick: Ninety percent is great. It is much more than the current vaccines we use against flu, which are only 40-50% effective.
The data from the Pfizer trial has yet to be published in a peer-reviewed medical journal. Is there a danger of getting our hopes up too soon?
Lang: The data they have published is only an interim analysis, but this trial will continue and be submitted to a peer-reviewed journal. But what is more important is that the regulatory bodies will interrogate the entire data set. When a scientist is submitted to a journal, he can choose what is included. But when you submit to a regulatory body, the MHRA, the FDA or the EMA, you must submit absolutely everything, the good, the bad, everything.
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