“All approved Covid-19 Vaccines are the same”. Or are they really?

WHO and govt agencies, in their eagerness to get as many vaccinated, want to tell us all vaccines are the same. But in reality it is a little more complicated than that.

At the start of the Covid-19 pandemic, I had posted to my friends on social media on how the advice from authorities and govt may not always be the best for selfish individuals seeking to protect themselves during the pandemic. Here’s a screen-grab of my post below:

A partial screenshot of my post on why some advisory on the pandemic from authorities may fall short.

As you can see, my argument was that a govt or health authority needs to act in the larger interests of the public. And it will not decide based on what is good for us at an individual level. Further, in that post I had argued that the data at the time was also lacking on how the pandemic will progress, or on what are the best practices. Hence I said it may be prudent to err on the side of caution and wear a mask or close the borders.

I find this scenario repeating with vaccines now. Neither do we have a good amount of long-term data on efficacy, nor are govt and their agencies setting up their vaccine advisories for your individual interest.

The govt and authorities would want as many vaccinated as quickly as possible to crush the pandemic. And to prevent newer strains from emerging to pose a long-term problem. So such consideration alone, along with a vaccine at hand, approved for safety and an acceptable efficacy, would be enough to ask you to go take it, no matter which one.

There’s no question such a strategy is important and extremely useful for the greater public good. But what if you had a choice and you can consider options from a half dozen vaccines that are now available worldwide? Is there a better vaccine? Or all vaccines created equal?

To consider this question, we need to look at the currently available data on the vaccines that are in use against Covid-19. But as said earlier, like in March 2020 when such information on the pandemic was lacking, it is a similar scenario now with vaccines. Though, recent pre-print research papers offer some insights for us comparing the different vaccines. We are at present are using three different types of vaccines: m-RNA, DNA viral vector, and inactivated whole virion.

The m-RNA vaccines use a very novel approach to vaccination. The vaccines use a strand of message that tells our cells to manufacture specific proteins on the surface of the Covid-19 virus. This delicate m-RNA (the message) is injected into our body encapsulated in a nano-lipid membrane, in order to preserve it better and enhance uptake into our cells.

As our cells read the instructions to produce the spike proteins, our immune system acts and we develop immunity against the real Covid-19. The Pfizer and Moderna vaccines use this technology. And in real world results, they seem to work well, offering an efficacy of close to 95%. Vaccines like J&J and AstraZeneca, on the other hand, use a viral vector to deliver the spike protein encoding message into our cells.

Instead of m-RNA, these vaccines use a part of the DNA from the Covid-19 virus that encodes the spike proteins. And they put this inside another virus to take it into our cells. For example, AstraZeneca uses a Chimpanzee Adenovirus that causes cold. It’s used in place of a human cold virus to which many of us may already have immunity to, thus rendering it ineffective. These vaccines have efficacy rates lower than m-RNA, ranging from 65 to 90%.

The third type of vaccines, like India’s Covaxin, use a much more traditional method of inactivated whole virus. Where they treat a whole Covid-19 virus to inactivate it. We then inject it into the body with some adjuvants that trigger our immune system. The immune system then recognizes this inactivated virus and produces antibodies to Covid-19. These vaccines currently in the market seem to show an efficacy of 50–80%. With Bharat Biotech’s Covaxin posting a 81% efficacy in interim phase-3 trial results.

Now the efficacy data, though important, isn’t too relevant for authorities. As per WHO standards, authorities can approve for use any vaccine over 50% efficacy. It doesn’t immediately matter for them if you have a 20% chance of catching Covid-19 after vaccination or 10% chance. What is important for authorities is all these vaccines create herd immunity and reduce the risk of severe Covid-19 infections. With some vaccines like the Pfizer/BionTech one, seem to eliminate hospitalization because of Covid-19.

There’s also the question of how long do these vaccines provide us with immunity. Since it is early days, it is hard to say with available data. But some research has come up recently that seems to offer some insight into the period of protection offered by various vaccines in the market. We need to mind that the research is pre-print and not peer-reviewed.

The study finds that the Pfizer and Moderna m-RNA vaccines performed the best, with an efficacy of 95 percent at the start. And dropping to 50 percent only around day 200. Covaxin starts at 80% efficacy after administration, dropping to 50% on the 149th day. The J&J and AstraZeneca vaccines, which had an initial efficacy of around 70%, reached the 50 percent mark around day 48. In contrast, the Sinopharm vaccine, with a starting efficacy of just 50 percent, seemed to offer no protection at all.

Table showing how efficacy reduces over time for various vaccines as per this research.

Now, there’s also the case of mutations that we need to consider. The m-RNA and DNA based viral vector vaccines encode only a few spike proteins on the surface of the Covid-19 virus. And our body’s immune response develops specifically to target these proteins. When mutations happen in the wild variant of the Covid-19, if the surface proteins encoded by these vaccines in their m-RNA or DNA change, then the efficacy of these vaccines takes a hit.

In contrast, a vaccine like Bharat Biotech’s Covaxin uses a whole Covid-19 virus. And hence theoretically the immune response by our bodies should be better able to deal with mutations and variants of the virus. This is one reason I prefer to get Covaxin personally. Though I should caution there’s no real world data to validate the hypothesis.

Hence, for individuals who can and want to choose their vaccine against Covid-19, there are definitely some important factors to consider. From efficacy, to longevity of the immunity provided, to theoretical efficacy against variants can all be factors.

And for health authorities and governments, it is time to acknowledge such differences in vaccines and plan better for their vaccination programs. It is important to understand that all vaccines may not be created equal. And there needs to be a strategy incorporated in public policy to address the long-term effects of discrepancies in vaccines and their efficacy.

It may very well be wise for countries to not hoard and use all authorized vaccines from around the world in a bid to mass vaccinate quickly.

A blogs a worldview at ablogs.medium.com

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