The authors of the Cleveland Clinic Study are confused, and this may be why their finding is being misinterpreted


Dr. Scott Solomons:

The results are clear: unvaccinated employees at the Cleveland Clinic had the least amount of covid infections. The odds of getting covid went up with each successive injection. 

The researchers’ conclusion is baffling because they claim that the new bivalent vaccine given to working-aged people offered modest protection against covid. I don’t know how they can claim protection because their data shows that the more vaccinations workers had, the greater the odds of catching covid.


Cleveland Clinic paper does not say the bivalent booster increases the risk of catching COVID, but rather, that it reduced infections by 30 per cent.

Author of the article:

Christopher Labos  •  Special to Montreal Gazette

Published Feb 07, 2023  •  3 minute read

Recently, some people have been spreading the idea that getting additional doses of the COVID vaccine increases the risk of catching the virus. The suggestion was made in an opinion piece in the Wall Street Journal and repeated recently by Florida Governor Ron DeSantis. The notion seems to stem from a preprint uploaded last December by researchers from the Cleveland Clinic. Opponents of vaccines have been using it to argue their case, worrying a fair number of people, if the emails I have received on the subject are any indication.

Article content

The Cleveland Clinic study is such a preprint. But even if we put concerns about preprints aside, this one fundamentally does not support the things people are saying it does. It does not say that the bivalent booster increases the risk of catching COVID. The top line results show that the bivalent booster reduced COVID infections by 30 per cent. This result is supported by a recent New England Journal of Medicine analysis that found the bivalent booster was better than the original vaccine and had an effectiveness of 59 per cent against hospitalization and 62 per cent against hospitalization or death.

The claim about vaccines making things worse stems from some of the secondary results and appears to fall victim to an epidemiological concept called the Table 2 fallacy. The name comes from the convention that Table 1 in most papers presents the characteristics of patients and Table 2 looks at the relationships between various factors and the end result being studied.

Here’s an illustrative example. If you were studying whether people who carry lighters are at increased risk for lung cancer, you would have to adjust for smoking status. People who carry lighters are indeed more likely to get lung cancer. But if you adjust for smoking status, then obviously, it’s not whether someone carries a lighter per se that predicts lung cancer risk. Conversely, if you wanted to see whether smoking increased the risk of lung cancer (by comparing smokers to non-smokers), the presence or absence of a lighter in someone’s pocket shouldn’t affect the results all that much.

The Table 2 fallacy states that you should not assume that all factors should be adjusted for in the same way. If you want to study lighters, you should adjust for smoking. But if you want to study smoking, you don’t really need to adjust for lighter ownership. These relationships are not interchangeable.

So, if researchers want to study the benefits of the bivalent booster, they should adjust for prior vaccination. But the same formula cannot be used to tell you anything about the protective or harmful effect of prior doses that you adjusted for. It is a subtle but important mathematical principle that is often overlooked. Because if you want to study the number of prior doses, a much more important variable to consider is the timing since your last dose, which is probably more important.

Christopher Labos is a Montreal physician and co-host of the Body of Evidence podcast.


Dr. Scott Solomons

January 9, 2023

The Surprising New Cleveland Clinic Study on the Bivalent Vaccine Efficacy

The Cleveland Clinic studied over 51,000 employees to see how effective the bivalent Covid-19 vaccines have been up until the close of the study on December 12, 2022. The start date was September 12, 2022. They specifically looked at reinfection incidence with covid-19 after one, two, three, and three-plus vaccines. The results are neatly presented in a line graph which we will look at later in this post. Two things really stand out. The first is that the more vaccinations the employees received, the more Covid-19 they got. The second thing is how the research paper described the vaccines as effective. I can’t tell if this is a joke, as the paper is in pre-print and under peer review. First, we will look at the study with the results, and then we will review their uncanny conclusions and discussion. You can read the study here.

This study aimed to evaluate whether the new bivalent COVID-19 vaccine protects against COVID-19. The strengths of their study include the large sample size and its accounting for who had COVID-19, when COVID-19 was diagnosed, who received a COVID-19 vaccine, and when. The study methodology, treating bivalent vaccination as a time-dependent covariate, allowed for determining vaccine effectiveness in real-time. A potential weakness is that the average age of the employees was only 42, the age for which most covid infections are rarely severe or fatal. For this reason, the researchers claimed not to be able to determine if the vaccines led to milder cases with fewer symptoms. 

The major flaw in the study, as in all vaccine studies, is that the individuals were considered unvaccinated until one week after their injections. Curves for the bivalent vaccinated state were based on data from when the bivalent vaccination status changed to “vaccinated.” This meant that the vaccinated group could have had covid cases in the first week that got placed in the unvaccinated category.


Katie Couric Media

January 10, 2023

Does Getting Boosted Make You More Susceptible to Covid?

By Katie Couric Media

Yes, new research is surprising, but experts urge caution.

Covid cases are rising and new variants without easy-to-pronounce Greek letters are running rampant. With masks once again an encouraged accessory, it’s rational to wonder if Covid will ever be a distant memory. Which begs the question, Are we just supposed to keep getting a Covid shot every single year, forever? Now, a controversial article seems to be legitimizing what anti-vaxxers have been saying for many months: that vaccines could be making people more likely to catch Covid. But is that really the truth? Trying to wade through all the research is enough to make your head spin, so we spoke to an expert to try to make sense of this confusing news.

This claim — that having more vaccine doses makes you more likely to get Covid — comes in part from a study, which has yet to be peer-reviewed and is pre-publication, from the Cleveland Clinic. The study looked at 51,000 of its employees and examined how many had gotten vaccinated and gotten sick from Covid. It found that, among the employees evaluated, incidence of Covid-19 increased as the number of vaccines increased.

But Dr. Najera cautions that correlation doesn’t equal causation. In other words, just because the risk of Covid-19 increased with the number of vaccines received, doesn’t necessarily mean that more vaccines makes people more susceptible to Covid. There are also a number of confounding (aka complicating) factors in the study. For one, healthcare employees, Dr. Najera points out, are more likely to be required to get vaccinated, so they may be more vaccinated than other populations. On top of that, they’re more likely to be exposed to people with Covid, which would make them more likely to get sick. “You put those two together, and it’s going to seem like people who are highly vaccinated are also going to be at higher risk of getting infected. But both things are related to the nature of their work, and that is a confounder.”

Another reason Dr. Najera urges caution regarding the results of this study is that it doesn’t have a control group of non-healthcare workers, so it can’t really be applied to the general population.



The bivalent booster vaccine does not increase chances of COVID-19 infection

Gov. Ron DeSantis falsely claimed ‘you’re more likely to get infected with the bivalent booster.’

By: Yacob Reyes

January 24, 2023

As he proposed to extend the state’s ban on mandates for COVID-19 vaccines and face masks, Florida Gov. Ron DeSantis lobbed a flurry of criticism at President Joe Biden and “the medical establishment.”

“They were not following the science,” DeSantis said at a Jan. 17 press conference in Panama City Beach. “Almost every study now has said with these new boosters, you’re more likely to get infected with the bivalent booster.”

Although some people have suggested the bivalent COVID-19 booster offers little protection against infection, DeSantis went further. He said people who received the bivalent booster shot were more susceptible to COVID-19 than those who hadn’t.

The governor’s press office responded to PolitiFact’s inquiry about the claim shortly after publication, citing two articles and three studies, two of which are not yet peer reviewed. The most recent came from the Cleveland Clinic and was discussed in an opinion article in The Wall Street Journal.

Dr. Nabin Shrestha, an infectious disease physician and one of the study’s authors, told PolitiFact that the data did not find a link between the bivalent shot and a higher risk of contracting COVID-19. The early conclusion was the opposite of what DeSantis said: The dose is, in fact, effective in preventing infection.

DeSantis’ conclusion could not be drawn from that study

Cleveland Clinic researchers examined the bivalent booster’s effectiveness in preventing infection among 51,011 health care workers  — some of whom had not received the booster — from September to December 2022. Pfizer and Moderna offer the bivalent booster, which the U.S. Food and Drug Administration authorized in August.

Over those four months, about 5% of the clinic’s employees contracted COVID-19. The researchers then estimated that the bivalent booster was about 30% effective in reducing the likelihood of contracting the virus.

The Cleveland Clinic researchers were not trying to determine the bivalent vaccine’s effectiveness in preventing severe illness or hospitalization.

“The study wasn’t measuring the vaccine causing infection,” said Jill Roberts, a public health professor at the University of South Florida. “The study was measuring the efficacy of the bivalent vaccine in preventing infection.”

What drove coverage in outlets like The Wall Street Journal was an “unexpected” association researchers found between the number of prior vaccine doses and an increased risk of contracting COVID-19. People with three or more doses of the vaccine had a higher chance of getting infected.

That finding quickly overshadowed the protection the bivalent shot provided. The Wall Street Journal opinion piece cited the Cleveland Clinic’s study as evidence that vaccine boosters are making “the population as a whole” more vulnerable to COVID-19.

Our ruling

DeSantis said, “Almost every study now has said with these new boosters, you’re more likely to get infected with the bivalent booster.”

An unpublished study from the Cleveland Clinic examined the bivalent COVID-19 booster’s effectiveness in preventing infection among a group of about 50,000 health care workers.

However, one of the study’s authors told PolitiFact that the research did not find an association with the bivalent booster and a higher risk of COVID-19. The study found that the bivalent booster is 30% effective in preventing infection from the virus.

The researchers did find that there could be an association between the number of prior vaccine doses and an increased risk of contracting COVID-19. Still, that finding did not suggest the bivalent booster could cause infection or increase the likelihood of infection.

We rate DeSantis’ claim False.


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