These Covid-19 Vaccines Are Safe, Right?

Sam Fazeli, a Bloomberg Opinion contributor who covers the pharmaceutical industry for Bloomberg Intelligence, answered questions about the safety of new Covid-19 vaccines that are set to win approval for broad use in the U.S., Europe and elsewhere as early as this month. The conversation has been edited and condensed.

Pfizer Inc. and BioNTech SE’s coronavirus vaccine was cleared for use by the U.K. on Wednesday after trial data indicated it works well at preventing Covid-19. Their shot, as well as one from Moderna Inc. — both based on new technology — are on the verge of gaining similar approval in the U.S. and Europe. Other inoculations in the works from AstraZeneca Plc and the University of Oxford, Novavax Inc. and Johnson & Johnson are in the late stage of trials, with approval likely within months. This is extraordinary. These vaccines appear to have been developed at breakneck speed. How is this possible when it typically takes years to develop an effective inoculation?

SF: The Pfizer-BioNTech and Moderna vaccines may seem brand new, but they are the culmination of more than a decade of work that started during the SARS and MERS outbreaks. Vaccines were even developed against MERS but were never needed. Nevertheless, scientists learned a huge amount from working with that virus, which is from the same family as the one that causes Covid-19. Remember also that technology has evolved rapidly — for example, we’re now about able to sequence the genomes of every mutant version of the virus in less than a day. That helps in speeding up vaccine development. Here’s something else that’s different: In the past, drugmakers would be sure that they had a potential viable product before ramping up manufacturing. With Covid-19 vaccines, as regulators from around the world got involved right at the beginning, companies took financial risks at stages of vaccine development that they would never have done before. All this explains why we’re seeing vaccines arrive so quickly.

If the U.S. Food and Drug Administration approves these vaccines as soon as this month, how much safety data will we have on them by the time they start getting distributed?

SF: We usually know if a vaccine is going to cause serious side effects within about two months of vaccination. Using that time frame, we will have oodles of data. Just thinking about the Pfizer-BioNTech and Moderna vaccines, close to 40,000 people will have received two shots of the vaccine by the time they are potentially released into the general population early next year. And many of these will be at the fourth or fifth month after their first dose. By way of comparison, GlaxoSmithKline Plc’s star shingles vaccine, Shingrix, was tested in about 28,000 subjects, half of whom received the vaccine. None of the side effects reported for the vaccine — which were the usual fever, chills and aches after a shot — occurred later than three months after vaccination.

The vaccines made by Pfizer-BioNTech and Moderna use new technology that harnesses messenger RNA. Unlike traditional inoculations, which typically inject a weakened strain of a virus to trigger an immune response, the “mRNA”  creates the response by actually instructing cells in the body to develop virus proteins. Isn’t this risky? Does it change the nature of those cells and could it trigger our immune systems to attack them?

SF: There is nothing odd or dodgy about using messenger RNA as a vaccine. It doesn’t genetically modify your cells and it is a short-lived molecule. When the mRNA carrying the “instructions” for making the virus protein gets inside a human cell, it joins the thousands of other RNA molecules there. As soon as the cell creates the virus protein, the body recognizes it as a foreign agent, just as if we had injected the protein directly (which is what most vaccines do). The immune reaction is focused against the protein and not the human cell that is making it. Nothing has changed about that cell. 

Results from different vaccine trials suggest different levels of efficacy. Are some vaccines better than others? Should I be worried about which one I get?

SF: What we know is that two of the mRNA vaccines in development, Pfizer-BioNTech and Moderna, have shown more than 90% efficacy — levels that no one dared imagine before they reported their results. AstraZeneca and Oxford's vaccine has shown potentially less efficacy, but we need to see more data on that. It is not a completely unexpected outcome given their earlier data, complex trial and the way the vaccine was designed. But, even with 62% efficacy — and it could be higher in younger individuals — the Astra vaccine can still have major utility in helping us get out of the pandemic. 

Still, are they totally safe? There have been side effects, right?

SF: Yes, there have been side effects. But they have been the type that are totally expected after a vaccination, such as fever, headaches and muscle or joint aches, which only last for a couple of days. I have to say, I am glad I see side effects. They are the results of an immune reaction, and you get them with the aformentioned Shingrix vaccine and many others as well. It is a sign that the vaccine is doing its job. Frankly, I can't wait to get two days of side effects so that I can regain my freedom. And they won't all be the same. We already know, from the little data provided, that the Pfizer-BioNTech vaccine seems much better tolerated, but more complete details will come out when the FDA meets to review the early use applications. For Pfizer-BioNTech, that’s Dec. 10; for Moderna, it’s Dec. 17.

So do we not need to worry at all?

SF: Worry is too strong a word. We need to be very vigilant and continue to follow the virus and its evolution, in case it finds a way around the immunity produced by our vaccines, like the flu virus does. But that shouldn’t keep us from embracing these new vaccines. We cannot continue to live our lives like this. Vaccinations have solved so many problems for humanity: measles, smallpox, polio, etc. There is always a risk that after 1 million people have been vaccinated you see some extremely rare side effects. But our other choice is to do what we are doing now and completely clog up our hospitals and intensive-care units while increasing numbers of people are suffering from long Covid. I choose vaccines any day.

This column does not necessarily reflect the opinion of the editorial board or Bloomberg LP and its owners.

Bloomberg Opinion provides commentary on business, economics, politics, technology and markets.

©2020 Bloomberg L.P.

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