Yes, the COVID-19 Vaccine Is Still Working Well

“Translate for me, please. Is this paper saying vaccines don’t work as well for people with obesity?” This question came from a dear friend and the short answer is no. That’s not what this paper shows. The paper in question is a preprint – which means essentially that it is a draft report of research with no peer review yet. It sounds impressive. It’s real-world data from an HMO in Israel with 1.6 million members. And the bottom line makes sense. The Pfizer-BioNTech COVID-19 vaccine is working well, consistent with how it did in clinical trials.

However, it pays to take some of the details with a grain of salt. The authors mention in their abstract that “VE [vaccine efficacy] for infection was lower for participants aged 75 and over, and for those with hypertension, diabetes, and obesity.” But this observation is just that – an observation from an uncontrolled, non-randomized study that doesn’t alter an important, basic fact.

That fact is that all three vaccines approved for use in the U.S. work quite well for people with obesity. In fact, data from controlled studies consistently show that there’s no difference in efficacy for people with obesity compared to all other subjects.

A Retrospective Observational Study

On Twitter, this study sounds really impressive. First of all, the mention of 1.6 million subjects grabs our attention. Such a big number suggests we should take this seriously.

Indeed, these big numbers give statisticians a lot to work with. But those big numbers don’t tell the whole story. This is an uncontrolled study of a dynamic population. It’s observational and vaccination is by individual choice – not random assignment. There’s no placebo, so it’s not blinded. That means that people knew if they had the vaccine (or not) and they could – and likely did – adjust their risk behaviors accordingly.

Results Consistent with Clinical Trials

After crunching this huge dataset, the researchers came up with results remarkably consistent with the findings from the well-controlled clinical trials of the Pfizer vaccine. Overall efficacy of the vaccine was 93 percent – not really different from the 95 percent efficacy in the controlled clinical trials.

The crude estimate for vaccine efficacy in people with obesity was 96 percent. After statistical adjustments, that came down to 90 percent. This compares with 95 percent efficacy seen in controlled clinical trials. The same number – 95 percent efficacy in people with obesity – popped up in data from a mass vaccination study recently published in NEJM.

So bottom line, it’s clear that this COVID-19 vaccine is still working well in people with obesity.

Vaccines Offer an Amazing Solution

Right now, we are fortunate to be in a place that is very different from just a few months ago. New COVID-19 cases are down – now less than a tenth of what they were a few months ago. This is because of vaccines. Three new studies tell us that these vaccines offer lasing protection and can likely be adapted as the virus evolves.

The places that are not doing well right now are communities – either by choice or misfortune – that have not been getting vaccinated in sufficient numbers. We have an answer to the misery of COVID-19. Let’s get it to everyone who needs it and let’s use it.

Click here for the preprint study from Israel, here for the study published in NEJM, and here for further perspective about the ongoing value of COVID-19 vaccination.

Farm Women at Work, painting by Georges Seurat / WikiArt

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June 29, 2021