People want the Covid vaccine to be worse than it is

One very bad study is causing alarm about fertility. Calm down.

The Covid-19 mRNA vaccine was a bad vaccine. It didn’t prevent you from getting Covid¹ or spreading it, and its side effects were pretty nasty by modern vaccine safety standards. Yes, it made Covid less severe for many people and may make infection less likely to develop into long Covid (it’s real, sorry), but there’s also evidence that vaccinated people are actually more likely to catch the newer strains than those with only natural immunity. The newness of the biotechnology, as well as the widely shared reports of terrible side effects, some real and some not, led a lot of people to decide to take their chances with the virus instead. This was a problem because many states and municipalities severely limited the rights of the unvaccinated to eat in restaurants, shop, go to an office, or hold onto their government employment. This was perhaps understandable when it was still widely believed that vaccination prevented infection and spread, but such policies remained in force long after it was discovered this wasn’t the case and were therefore indefensible from a public health perspective. A lot of people lost their jobs, and most of them have not been compensated for this injustice.

As for myself, I got three shots in total. The second and third both knocked me out of commission for over a day with terrible flu-like symptoms, the worst of which was a pounding headache. I also got Covid on top of that at least once that I know of. It sucked, I sure wish there was an effective vaccine against it. In general I’m a vaccine enthusiast — I am up to date on all my major shots and get a flu shot every fall. I’ll get the shingles vaccine the moment they let me (not old enough yet). But knowing what I know today, the Covid vaccine strikes me as very poor in a cost-benefit analysis. If the flu shot made me feel as terrible as it does, for as little benefit, I wouldn’t get it either.

All of this preamble is to say: I fully acknowledge that the vaccine is quite bad. I don’t know if I regret getting it, but I’m certainly not getting any more boosters. I don’t recommend people get it unless they’re very elderly or have some very serious health issue and need its meager protection against severe Covid.

But. From the very beginning of the vaccine rollout, the conspiracy-minded corner of the internet was roiling with outrageous rumors about the vaccine causing terrible health problems. These kind of run the gamut — maybe you’ve seen claims from always-anonymous morticians about finding a deceased vaxxer’s blood replaced with red goo, one giant whole-body clot. After seeing enough of these wild claims blaming every random health problem on the vaccine, they become self-parodying.

But while some claims about vaccine harms were really wild, most center on three specific fears: cancer, heart attacks, and reproductive harm. The latter in particular really captured people’s imaginations, with persistent fears that vaccination would lead to fertility issues or outright sterility in women (or maybe just girls, in some rumors). The most conspiracy-minded like to allege that this was All According To Plan of the sinister powers that want to reduce the population. It’s easy to find claims of this nature, and I’m sure you’ve seen some shared on social media. Many of them are accompanied by specious or badly misinterpreted data. They don’t draw in anybody but the most credulous, and you mostly have to just laugh them off.

But an especially bad study came across my feed recently that made some pretty big waves, and it made me pretty angry. Its data is real, but its frame and analysis are very dishonest, bordering on academic fraud.

The title is “Rates of successful conceptions according to COVID-19 vaccination status: Data from the Czech Republic”. The authors accessed publicly available, anonymized health data from the Czech Republic, and were able to track the fertility of individual women who had gotten the vaccine compared to those who had not. Here’s their main finding.

Pretty scary, right? Vaccinated women are conceiving at a roughly 33% lower rate than the unvaccinated. Sounds really bad, doesn’t it? Twitter certainly thought so, with one prominent tweet sharing the study collecting hundreds of comments and quotes all repeating the same claim: the shot caused a 33% drop in conception rates. Here’s a typical specimen.

But read the study. Just the first section, really.

We used nationwide data from the Czech Republic to examine rates of successful conceptions (SCs), that is, conceptions leading to live births 9 months later, for women who were either vaccinated or unvaccinated against COVID-19 before SC.

So here the authors pull a neat trick: they measured the birth rate, then called births “successful conceptions” (not technically a lie) in order to imply that vaccinated women were trying to conceive and failing. But in fact, all this study demonstrates is that women who chose not to vaccinate had more kids than those who got the shot, for reasons that are very easy to speculate about (more on this in a bit). Later in the study the authors admit as much in a series of disclaimers they knew would be ignored when their paper was shared.

The observed association between decreased SC rates and COVID-19 vaccination is, of course, not proof of a causal relationship between vaccination and fecundability. For example, it is possible that more women who wished to become pregnant, that is, achieve SC, chose not to be vaccinated, and/or that more women who did not plan to become pregnant opted for vaccination. Indeed, such self-selection bias is compatible with the increase in SCs of the women unvaccinated before SC in the second half of 2021

…

The current study should be interpreted in view of other limitations that include, for example, unmeasured confounders such as the age distribution of the 18- to 39-year-old women, socioeconomic and lifestyle factors, comorbidities and sexual health, effects of individual COVID-19 vaccine products or vaccine boosters, concurrent COVID-19 infection, preconception fertility, contraception use, pregnancy loss, stillbirths, and paternal health and vaccination status.

These disclaimers strike me as disingenuous given the choice to relabel the birth rate as “successful conceptions”, a move obviously meant to imply a causal relationship in ability to conceive. But at least they included them.

To recap, they don’t know:

• How old the women in each cohort are (i.e. maybe older women were more likely to vaccinate)

• If there was selection bias in whether prospective moms opted out of the shot given fears of the new tech

• Whether unvaccinated women differ in other ways that impact fertility, e.g. “lifestyle factors” (i.e. religion) or location (urban v. rural)

And are there predictable, large differences in fertility among women with different “lifestyle factors”? In a word, yes.

Weekly exposure to holy water results in a 33% increase in successful conceptions

Living near a bus route causes a 10% reduction of successful conceptions

Voting for sexy, sexy Donald Trump causes a massive doubling in successful conceptions

This last point is especially salient because this latest round of vaccine skepticism is, unlike 10 years ago, no longer a feature of crunchy affluent liberal moms in California letting their kids get measles. This time it’s mostly rural conservatives shying away from the needles.

But wait, you say, didn’t the vaccine rollout in other places correlate with similar declines in the overall birth rate?

This is true, but I’m begging the credulous on this topic to consider whether anything else might have happened during the period from 2020 to 2023 that could have impacted people’s family planning, for example a global pandemic and a recession. Things are better than they were, but Western countries are still not back to normal — there’s a heartbreakingly large minority who are still refusing to leave their houses. But despite this, Sweden and many other countries have started to recover their fertility after the low of 2023, with even a little bounce back. You need to include data from 2024 to see this.

Just imagine how harmful the vaccine rollout of 1994 must have been

As for heart problems: those are real, but with the exception of men under 40 getting the Moderna shot, Covid infection itself was much worse. Choose your poison.

We can talk about cancer some other time, as it’s a more involved topic and not as easily discredited as fertility concerns.

The world is a scary place, and Covid made it scarier. It’s only natural that many people seized on the draconian vaccine rollout as an all-purpose boogie man they could blame for every ill after it inflicted such obvious and real harms on their personal liberties and livelihoods. But while the vaccine was quite bad, people really want it to be much worse. They want it to be responsible for our every health ill since 2020, and especially for our declining birth rates. Part of me wishes it were really that simple — it would give us something we could potentially fix with medicine. But despite the global pandemic twisting the knife a bit when it comes to getting in the mood for making babies, the sad reality is that birth rates in the West have been in free-fall since the sixties, and the culprit is simply ourselves. As far as I’m aware, getting the Covid shot doesn’t make one any less likely to get off birth control, find an attractive partner and raw dog them. That’s the only thing that will reverse the decline.

1. Technically this should be COVID-19 in all caps, but this looks frankly wrong to me, like capitalizing “internet”. Also it stands for coronavirus disease, so if anything it should be CoViD but nobody does that. And also again, the virus’s actual name (not the disease, the virus that causes it) is SARS-CoV-2, i.e. SARS 2 but they nipped that one in the bud early in the pandemic, the first of many sacrifices of factual accuracy designed to manage public health outcomes.