A long Tweet thread claims that because of flaws in electronic health records, public health officials do not know who has been vaccinated, so they have no way of claiming that unvaccinated people are more likely to die from COVID.

The main point here is that we can’t just assume all people with “unknown” vaccination status in studies are unvaccinated.

In one study, 44% of the “unknowns” were actually vaccinated, so it’s not accurate to think that “unknowns” automatically mean they’re all unvaccinated. The data even shows that “unknowns” have higher COVID rates than those who are confirmed to be vaccinated.

This statistic suggests that vaccines do help protect against COVID because the part of the “unknown” group that got vaccinated is likely lowering the overall COVID rates in that group. So, if more than half of the “unknowns” might not be vaccinated and their COVID rates are still high, it means the unvaccinated people could be getting COVID even more than the numbers show.

We know that more people died in places where fewer were vaccinated. In the second year of the COVID-19 pandemic, when vaccines became widely available, this study showed that while large metropolitan areas saw a significant reduction in deaths, rural counties in the U.S. experienced more excess deaths due to challenges in vaccine access, higher vaccine skepticism, and healthcare limitations.

A story from 2013 is again circulating. In the story, a 19-year-old man died after receiving a flu shot, and the family pinned the blame on the shot.

Acute disseminated encephalomyelitis (ADEM) is an autoimmune disease wherein inflammation attacks the brain and spinal cord. It can occur after any bacterial or viral attack.

ADEM is extremely rare, and more than half of ADEM cases occur after a viral or bacterial infection. Most cases occur 4-14 days following infection.

Though it is possible that a vaccine could cause ADEM, The Health and Medicine Division (HMD) of the National Academies of Sciences, Engineering, and Medicine (previously the Institute of Medicine) in 2012 said evidence of a causal link is weak.  It is so rare to occur after a vaccination that there are case studies about such occurrences.

In this case of ADEM after influenza vaccination, the patient became sick within 24 hours of vaccination. He died 28 days later with no apparent cause of death, but the family refused an autopsy. The family was the main driver of the belief that the flu shot was to blame.

A podcaster is running with the hypothesis that a new study proves that COVID vaccines cause autism.

Autism is a neurodevelopmental difference that, for the most part, occurs prior to birth. In one study, researchers found evidence that autism starts during pregnancy, based on analysis of brain tissue showing disrupted development in children with autism. These developmental differences were found in nearly all samples of brains from autistic children, regardless of the diversity of their symptoms.

The podcast’s claims that the COVID vaccine causes autism is based on a study that looked at a few selected chosen offspring of 15 female rats, some given a full, human dose of COVID vaccine during pregnancy, and determined there was an increase of “autism-like behaviors” in selected pups from the vaccinated group. These behaviors included decreased social interaction and increased repetitive behaviors.

Concluding from this study the COVID vaccines cause autism in humans is premature. The study itself cautions that “drawing conclusions from animal models has its limitations.” Secondly, the rats received large doses of the vaccine: the equivalent of a human receiving hundreds of vaccines.

Other histological testing that showed a difference between the vaccine and non-vaccine wings of the study was done with just 3-4 rats in each group, which is an extremely small sample size.

There are also concerns about the study design itself. The methods section gave no indication that the rats were blinded, meaning that the researchers likely knew which rats were born to vaccinated mothers. Since observation was a large part of the study, their biases could have influenced the description of their behaviors. Additionally, they didn’t actually look at known autism genes, nor did they use a positive control using an established autism rat model.

Moreover, we know from countless studies, vaccines are not associated with autism.