Does the COVID vaccine impair fertility?
I’ve seen people saying that this Czech study proves that the vaccine does impair fertility. But actually, the study does nothing of the sort. The most it does is raise a question that warrants further study.
To reiterate points I’ve made many times before, I think that if you look back at my posts on COVID and on the vaccine they generally hold up quite well. At the outset I thought the danger of the disease was overhyped, with the biggest danger to the elderly. I also thought the lockdowns were okay for a short time – “two weeks to slow the curve” – but went on way too long and were seriously damaging in a host of ways. As for the vaccine, it soon became clear that it promised much more than it delivered. I thought it had somewhat of an attenuating effect on the seriousness of cases of the initial more deadly strains, but it didn’t seem to fulfill its promise of stopping transmission. After that, it didn’t seem to do too much of anything although it might have continued to make symptoms a bit less serious, and many studies started appearing that people online were saying showed the negative side effects were worse than the benefits.
For a while I read each report carefully – not just the online descriptions of vaccine doom and gloom, but the reports themselves. I have yet to read a single one that proves what the online anti-vaxxers say it does. That doesn’t mean that one doesn’t exist that I haven’t seen. And it doesn’t mean that a new one won’t come out that has more convincing results.
I have no desire to rehash my reactions to each of these studies of the vaccine. You can take a look on the blog itself – for example, please see this previous post that summarizes some of my position, with links.
Now let’s go to the recent Czech study on the COVID vaccine and fertility. When I read it, what immediately leapt out to me was that the two groups – vaccinated and unvaccinated women between 18 and 39 – cannot be presumed to be alike, and that their differences may account for the disparity in conception rates. And sure enough, the researchers themselves say as much:
While the strength of our study is its nationwide unselected sample of fertile women, 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. Unfortunately, we were not granted access to this information. Also, the estimated SC rates for vaccinated women were uncertain, mainly in the early phase of the vaccination campaign.
It is really hard to get valid comparisons between two groups of people, especially after the fact. All the potential confounders have to be carefully balanced between the two groups, and if you missed any, then you are measuring the differing prevalence of the confounders and not the thing you are trying to test for.
What the H are “SC rates”?
Relatively early, like 2021 or so, there was a report released about a significantly increased rate of miscarriages of active duty women in the US military who were required to have the vaccine.
There continue to be issues with sample size and study membership, which is always an issue with studies especially on pregnant women since you’re largely limited to observation.
However, going through the IVF process in 2021-2022 and aware that there seems to be *some* impact on fertility though no one could identify exactly what yet, I did not choose to get any boosters, and I had the J&J vaccine first before it was pulled from the market, which was not one of the mrna ones. I was not willing to take a risk with the sole embryo we had.
Cicero:
I provided a link to the study. If you go there, it tells you quite quickly that SC stands for “successful conception.”
Kristen:
I hope you were ultimately able to have a child. I went through fertility problems long ago, and although fortunately I didn’t have to do IVF, I well remember how stressful it was to have fertility difficulties.
OK, Neo!
I believe in stand-alone commentary (SA!), instead of having to research for meaning.
” I also thought the lockdowns were okay for a short time – “two weeks to slow the curve””
I guess this theory never got tested, given the extension. But I don’t see how it would work. As soon as the 2 weeks are over, the “curve” would start again and end up where it would have gotten had there been no pause. The virus would not somehow have become more benign in the course of a mere 2 weeks. In other words, the 2-week pause might have, at best, delayed the course of the epidemic by . . . 2 weeks.
@Watt:In other words, the 2-week pause might have, at best, delayed the course of the epidemic by . . . 2 weeks.
The two weeks was intended to give the ICUs a little more time to get ready. That’s how it was sold at the time. Neo even wrote about it then.
A contemporaneous news article from March 12, 2020:
Niketas Choniates on June 26, 2025 at 6:23 pm said:
It is really hard to get valid comparisons between two groups of people, especially after the fact. All the potential confounders have to be carefully balanced between the two groups, and if you missed any, then you are measuring the differing prevalence of the confounders and not the thing you are trying to test for.
That’s true for a small test sample but this is 1.3M women.
@Don:That’s true for a small test sample but this is 1.3M women.
Not a sample size issue. It’s a population mix issue. If the vaccinated cohort skewed older, for example.
See this all the time in my health insurance career, because the 1-in-a-million cases are so expensive they skew the average materially, and if you actually have a million people the probability of getting one 1-in-a-million case is only 37%. There’s a 37% chance of not getting one at all, and a 26% chance of getting more than one. A little counterintuitive but nonetheless true.
Large sample sizes are simply not enough.
Some churches tried services in the parking lot, attendees in their cars. Others used drive-in theaters.
so…https://tennesseestar.com/news/democrat-governor-of-kentucky-orders-police-to-take-down-tag-numbers-of-church-goers-other-easter-gatherings-so-government-can-impose-2-week-quarantines-on-citizens/jmreynolds/2020/04/12/
A number of cases where drive-in theater services were prohibited or ticketed. Was this good science, or did the Little Hitlers love it as one more way to push people around? Or a yummy opportunity to stick it to the Christers.
@Richard Aubrey:A number of cases where drive-in theater services were prohibited or ticketed. Was this good science, or did the Little Hitlers love it as one more way to push people around?
My favorite case of this was how Nevada kept casinos open but closed churches. So one church had services in a casino, and Nevada closed THAT one.
It was really obvious, very early in, that was deemed “essential” was not based on epidemiology, but on something else. Churches: non-essential. Marijuana dispensaries: essential. Big box stores: essential. BLM riots: essential public health.
And I have worked in labs with bio and radiation hazards, and they sure don’t let you sit in a corner and eat as long as you pull your mask up between bites.
The probably self-selection bias leapt out at me the minute I read this report summary. Both the reluctance to take an experimental vaccine on the part of women intending to conceive, and the eagerness to take the vaccine on the part of liberal women who also were likely to be delaying or forgoing pregnancy altogether, seem like obvious enough correlations that any study would need to account for them.
There’s no substitute for random controlled trials. The most after-the-fact correlations can do is suggest areas for disciplined, reproducible experiments.
Some might find this rather astonishing article helpful.
“Cancer Patients Recover By Taking Repurposed Anti-Parasitic Drugs”—
https://www.zerohedge.com/medical/cancer-patients-recover-taking-repurposed-anti-parasitic-drugs
I hate it when I read a news story which is poorly edited from the “newswires” or wherever, and find “‘blah blah blah,’ Johnson said.”
Johnson? Who’s that? I go back to the top and skim the story, but alas, there is no mention of “Johnson.”
@ Barry > “Cancer Patients Recover By Taking Repurposed Anti-Parasitic Drugs”
Not the first time that has happened.
Most drugs seem useful for more than one problem.
Aspirin was deliberately concocted as an analgesic, but is now used just as much or more as an anti-clotting agent
I notice that the FDA only drags its feet on approvals when there is no political (or financial?) hay to be made from accelerating them.
I have a condition called trigeminal neuralgia (literally pain from the trigeminal nerve) that is exceedingly vicious; my neurologist says it may be one of the most painful chronic conditions known (he obviously has never experienced childbirth, but at least that’s over eventually).
My prescription is a repurposed drug for controlling epileptic seizures.
I don’t know if the FDA approved or not, but I do.
Two weeks to slow the curve was never a good idea because the massive extension of the timeline was entirely predictable. For three reasons:
1) “Foot-in-the-door” sales technique. A population that has agreed to a two week lockdown is MUCH more likely to agree to a two month or two year lockdown.
2) Deborah Birx has admitted that the goal of the two week lockdown was not to buy time for ICUs to prepare, but rather to get the lockdown ball rolling and buy time for policymakers to prepare and rollout more extended lockdown proposals/policies/justifications
3) Once an emergency precaution has been put in place, there are strong disincentives for politicians or bureaucrats to ease the precautions.
There are strong disincentives for policymakers to ever ease “precautions.” That’s why you are STILL going through expanded, time-consuming, Osama-Bin-Laden terrorism screening at the airport 24 years after the original “precautions” were added. Have ANY politicians or bureaucrats ever called for the screening to be relaxed? No. Because whoever eases the screening will be blamed for any subsequent airline incident. And avoiding personal responsibility/blame is a career imperative for politicians and bureaucrats.
Maybe in theory a two week lockdown might have accomplished something, although I doubt it. But in practice it wasn’t actually possible to do a two week lockdown as a discreet “measure.” It was inevitably the beginning of a slippery slope.
[Emphasis mine; Barry M.]
If what is being referred to is ventilators then there is no small irony involved, as—IIRC—the use of ventilators to treat the respiratory issues was, fairly early on, discovered to exacerbate the condition of the Covid patient to the point of killing that patient.
I imagine those deaths would have been officially classified as “caused by Covid”.
‘Barry. That Cuomo was using “venthilators” as a cudgel against Trump and to cover his ass regarding the nursing home death rate, and Trump wasn’t providing enough of them, they had to be pure gold. That’s science
Indeed.
And, in fact, I never quite understood why ANYONE thought that resuscitating Andrew Cuomo was a worthy idea…
Hey, speaking of pathogens, IT’S BACK! (that is, if it ever truly was eradicated…), as evinced in this courageous, eloquent article:
“‘We Are to Exist, Not to Live’;
“What working in a leper colony taught me about disease, anti-Semitism, and myself”—
https://www.commentary.org/articles/irina-velitskaya/leper-colony-disease-anti-semitism/
H/T Powerline blog.
A very significant percentage ( more than half ?) of medical studies cannot be replicated , so one needs to treat any study result with a skepticism.
Because the point was to inflict maximum pain why fauci and dazsak should be severely punished for what they did same with ferguson and murray who justified the lockdowns
Similarly an ethically challenged company like moderna should not have been given the approval
(An inconclusive study is not necessarily wrong.)
Now that the Covid-19 crisis has passed, mRNA vaccines should never be used again unless they can be conclusively proven safe.
There was negligence involved in every aspect of this process from the gain of function to the flawed therapeutic tests to the failure of control groups with testing collectivy that suggests an evil intent
To “control” in testing involving the health of humans brings up a number of issues. As one commenter mentioned, when the subjects chose which group to be in, the sorting process itself likely affected the results. And, with something so serious, you don’t fool people with placebos.
I think it was the editor of Lancet who said that half of everything published is crap. He should know.
However, even the slightest indication should be investigated in a way that doesn’t put people at risk. But what kind of test doesn’t? The control group at least doesn’t get the good stuff and thus no benefit which is available to the test group. Or the reverse.
The Covid 19 shots were demonstrated to be both unsafe: injurious and fatal,and ineffective (i.e. non-sterilizing immunity) in a significant cohort of the population. Proceed with judicious caution where the risk is warranted. Ironically, the risk stems in part from unpredicted (“unauthorized”) migration… a political correct vaxxxine.
If the Left really was the “party of science” they would have retained their initial skepticism of the vaccine while it was being developed before the 2020 election, allowed scientists to conduct (and then publish) proper research on it after it was rolled out, proved how injurious it was, and pinned the “crimes against humanity” on Trump and prevented him from getting anywhere near the White House again in 2024.
Instead they did a 180 flip after Biden was installed, took ownership of the vaccine, and treated it as a holy sacrament. Meanwhile, their adherents were happy to follow their orders, leading to children and young adults being among the most covid-vaxxed cohorts to this day.
If they hadn’t gone so all in on the covid vaccine, they would have still been able to hang Trump with it (who still likes to crow about his “operation warp speed”).
@ Hep (1:27am)– I’m with you on that. It seems the editors are more interested in saving “column inches” than they are in conveying information to the reader. They don’t know that they created the question— “who is Johnson, and why should I care what he (or she) said?”
Next on my list is over-use of pronouns to the point we have no idea what person or place is actually involved.
It does seem to be more a review of existing literature than new findings
One of the phrases I hear often from vax opponents, Tucker Carlson and Joe Rogan is “We know that . . . .” It gets used to signal absolute belief in an aspect of a controversy that is not only not proven, but lacks any proof.
I am not open to being shown that 73 snipers fired at JFK, nor am I open to being shown that Stanley Kubrick faked the moon landings.
I am open to the possibility that covid vaxes caused injury. I have not seen convincing evidence so far.
@Gordon Scott:I am open to the possibility that covid vaxes caused injury.
Every vaccine injures someone. Risks have to be managed. If you’re old or have chronic health issues COVID is far more likely to get you than the vaccine. Adults of course have the right and responsibility to decide for themselves how to manage that risk. But children have a lower risk of death from COVID than death from a car accident on the way to get vaccinated for COVID.
What risk of vaccine injury there is for them, even if it is very small, is comparable to the thing you are trying to vaccinate them against which does not make a lick of sense. The number of children who died of COVID is roughly the same as the number who drowned in bathtubs or 5-gallon buckets. No one has yet found that children contributed much to the spread of COVID, so it’s not as though vaccinating them protected vulnerable people as well as other precautions vulnerable people could have taken on themselves.
@ Charlie > “It was inevitably the beginning of a slippery slope.”
Not necessarily; Trump originally announced that we would be open by Easter.
That he didn’t stick to that goal was because the entire medical establishment supposed to be guiding him nixed it.
Maybe that dishonesty was inevitable, given what we now know about their rampant perfidy; maybe not.
At that time, I think he genuinely believed they were (a) honest brokers and (b) following the science.
Sadly, he didn’t drop that belief even after other doctors showed him how wrong the Fauci-Birx Cabal was.
In the beginning the rate of spread and the fatality rate were so uncertain, that if the high ends of the estimates were correct, we might have needed to bury people with bulldozers. In those first few weeks when so little is certain, that’s your prime chance to avoid a disaster.
In the end COVID was not much like the Black Death, it was like ten years’ of flu at once. In the beginning no one knew this.
I suppose we can count ourselves lucky we didn’t overreact as badly as China did, with teams going house to house dousing everything in bleach and killing pets and locking people into their buildings.
“The number of children who died of COVID is roughly the same as the number who drowned in bathtubs or 5-gallon buckets.”
Not just children. I live in Silicon Valley where the Santa Clara County health department kept a detailed running summary of COVID case and death counts. I decided that death counts were more reliable in tracking severity of the pandemic though of course there was ambiguity there as well, eg dying ‘with’ COVID vs dying ‘from’ COVID.
In any case I learned that the number of deaths of people under *50* was very small, comparable to death rates from ordinary flu. That is when I fully realized the lockdowns were insane because large numbers of people in the prime of life had their livelihoods taken away or severly impacted for no good reason. Not to mention their children in school. My own personal conspiracy theory belief is that the lockdows, which Democrats had opposed early on as “racist” (what else for them?) were imposed in order to derail the re-election of Trump which was looking awfully good in February 2020 with a good economy, no major foreign entanglements and the Dems on the verge of nominating Sanders.
Note that Santa Clara is a populous county (over 2 million) with a fairly diverse population both ethnically and socioeconomically so is likely representative.
Slight correction – Santa Clara County population not quite 2 million, actually about 1.9m
Getting to the bottom of actual Covid results runs into the fog of “died with” being equivalent in an unknown but large percentage of cases when death was the result of something else but recorded as “died of”, per Birx.
The same story with hospital Covid admits; 30% to 70% were “incidental”. That is, you come in for something and crank a positive PCR and…it’s Covid admit.
A report out of Greece showed about 40% of deaths “of” Covid were of something else. Not sure how solid the study was but the number has to be well above zero.
@ Niketas > ” if the high ends of the estimates were correct, we might have needed to bury people with bulldozers”
I began to really suspect “fake news” and collusion from the Democrats when the big cities were not shoveling homeless people into burn pits.
Not an original observation, but that was the change moment for me from benefit-of-the-doubt acquiescence to growing disbelief in the “experts” and Mr. Science.