Comparing Vaccines

As India is hit by the second wave of COVID-19, compounded by a new variant (mutant), one begins to wonder: when will it end? Will the ongoing vaccination drive, once it hits a critical number, turn the tide of new cases per day, like it seems to have done in Israel, the UK, and now in the US?

 

One thing felt strange though: the US and Israel are using vaccines with efficacy rates of 94% and above, while the UK is using one with a much lower rate of 67%. Something doesn’t feel right: with such a huge difference in efficacy rates, how could both the US/Israel and UK have similar outcomes (lower case rate)? This is a critical question for India, since after all, we’re using the British and Indian vaccines with much lower efficacy rates too.

 

This YouTube video was revelatory on so many fronts, including the questions above. First up, different vaccines were tested in different places and at different times:

•         Moderna and Pfizer were tested only in the US, and at a time when the case count in the US was not too bad;
•         Johnson & Johnson, on the other hand, was tested in the US, but at a time when the case count in the US had spiked up sharply.

It’s not an apples to apples comparison. The timing of the tests was different.

-         In addition, J&J was tested in other countries like South Africa and Brazil as well. During part of the trial, new mutants (variants) started rising in both countries. So the vaccine was really getting tested against multiple variants in those countries.

So we see that location of the trial matters too. The rise of mutants matters too (a vaccine designed based on one strain may not work against the other strains).

 

Everything above suggests Moderna and Pfizer v/s J&J is not an apples to apple comparison. On a side note, is this why Pfizer withdrew its vaccine submission in India? Not just because of the need for very cold storage conditions, but also because (1) it had not been proven effective outside of the US and (2) it had not been tested against other strains than the ones in the US?

 

And perhaps this explains the very high efficacy of the Russian vaccine at 92%. Wasn’t it tested overwhelmingly in Russia and thereby against one variant only, i.e., one place only and a time when no new variants arose?

 

The video then switches gears and points out that several healthcare experts believe that the very purpose of a vaccine has to be different based on context. Intuitively, we feel that a vaccine should prevent one from getting infected altogether. But when you’re dealing with a disease on a global scale, with different variants, is that even the right metric, they ask.

 

Huh? If that didn’t make any sense, let the video elaborate. In a pandemic, those experts argue, you look at the range of outcomes wrt the disease: death, hospitalized, severe symptoms, mild symptoms, no symptoms, and no infection. “No infection” is the wrong metric, they’re saying. Instead, if vaccines can restrict outcomes to the “mild symptoms to no infection” part of the spectrum, that’s good enough. Because then it’s just like dealing with a cold, between extremely uncomfortable and mildly annoying. If the vaccines can get us to that range of outcomes, then the world can go back to business as usual.

 

That does make a lot of sense. So how do all the vaccines fare on that revised criteria? Very well, indeed: all of them overwhelmingly (without much difference between them) do restrict the outcome to the mild to no symptoms band.

 

This would also suggest we need to stop worrying so much about this vaccine v/s that vaccine. On the other hand, if Pfizer can’t do well against the Brazilian or South African (or British/EU or now the Indian variants), well then, it’s just as well to not even use it in those countries: the 95% efficacy rate is against the variant in the US only.

 

On a closing note, this also implies that international vaccine passports are meaningless (after all, no vaccine has been tested in most countries). It also means international travel shouldn’t open up any time soon, even when more countries get vaccinated. Because that would just result in variants of the vaccine moving around the world and setting off the cycle all over again.