Back in March, I wrote about a study that was widely touted as showing that catching Covid lowers your IQ. The study found that individuals who’d had symptoms for more than 12 weeks scored about 6 points lower than those who hadn’t caught the virus. Even individuals who’d had an asymptomatic infection, the study found, scored about 2.5 points lower than those who’d never had one.
However, I was sceptical that these findings were explained by Covid having a large negative impact on cognitive ability.
The authors didn’t actually look at change in IQ scores, but rather at the cross-sectional association between Covid infection and IQ scores. Hence their findings could easily be explained by self-selection: people with higher cognitive ability may have been less likely to catch Covid, and may have been less likely to get seriously ill when they did catch it. As evidence, I noted that such people tend to work in professions that had lower risk of exposure to Covid, and tend to be healthier in general.
A new study has confirmed my suspicions: it appears that catching Covid doesn’t lower your IQ after all.
Bas Weerman and colleagues analysed data from the Understanding America Study – an ongoing longitudinal survey with a large sample size that began in 2014. As part of the survey, respondents complete a series of cognitive tests every two years. In March of 2020, they completed a questionnaire about the emerging Covid pandemic, in which they were asked whether they’d ever tested positive for the virus or been diagnosed with the disease by a healthcare professional. Around the same time, they were invited to participate in separate bi-weekly surveys, which also asked about their infection status.
The researchers therefore had data on respondents’ test scores before the pandemic, their infection status during the pandemic, and their test scores after they’d been infected (for those who had). This allowed them to test whether Covid infection was associated with a decline in test scores between the pre- and post-Covid waves of the survey.
Weerman and colleagues began by replicating the finding of the earlier study – that individuals with lower test scores measured before the pandemic were more likely to become infected. They then looked at whether individuals who became infected subsequently scored lower on the cognitive tests, and found they did not. Eight separate measures of cognitive ability were included in the study, and none of them was affected by Covid infection.
Together, these two findings strongly support my interpretation of the earlier study: self-selection is what explains the association between Covid infection and IQ scores. Rather than Covid infection causing lower cognitive ability, it appears that higher cognitive ability caused people not to catch Covid (or to catch the later, milder variants).
All those headlines about Covid making you less intelligent – about even mild infections knocking several points off your IQ – turned out not to be true. Given the media’s general tendency to exaggerate, overhype and sensationalise the threat from Covid, I wouldn’t expect this new study to get nearly as much coverage as the earlier one.
To join in with the discussion please make a donation to The Daily Sceptic.
Profanity and abuse will be removed and may lead to a permanent ban.
There was no pandemic.
There was a pLandemic.
If anyone needs someone to talk to we meet every Sunday.
Stand in the Park Sundays 10.30am to 11.30am From 1st January 2023
Make friends & keep sane
Elms Field (near Everyman Cinema and play area)
Wokingham RG40 2FE
What are the numbers for Belarus?
I just checked now. According to the same source, Our World in Data, Belarus (who largely ignored the pandemic and eschewed lockdowns) lost about two years of life expectancy, compared to four years in Russia (who was quite strict at first, though later less strict than the world average, and created their very own jabs). And another source actually says that they gained a fraction of a year.
Also, Nicaragua (who also largely ignored the pandemic) and Tanzania (ditto) either largely broke even in terms of life expectancy after a brief hit in 2020 (Nicaragua) or saw a small drop of less than a year (Tanzania). And Brazil didn’t do great, but fared better than their stricter neighbor Peru. Before the pandemic, Peruvians actually lived a bit longer than Brazilians, and now, the reverse is true.
And of course, Sweden largely broke even from 2019 to 2021 after a brief hit in 2020, and even gained a bit from 2018 to 2021.
There was no pandemic in the county where I live. FOI requests to local crematoriums and cemeteries proved that. Yet the council commissioned a permanent monument to the victims of the ‘pandemic’ which has been erected next to the town’s war memorial. I find it grotesque.
Joining in to shout something I and many others have been shouting since the start:
THERE WAS NO PANDEMIC!
Seconded.
The USA lost nearly two years of life expectancy from 2019 to 2021. Free Florida lost 1.5 years, while New York lost 3 years, twice as bad:
https://www.wfla.com/news/florida/floridians-life-expectancy-drops-by-1-5-years-according-to-cdc/
And California? They also lost 3 years. Of course, we know that China’s *other* weapon of mass destruction, fentanyl, also contributed mightily to this trend, especially in San Fransicko.
https://jamanetwork.com/journals/jama/fullarticle/2794146?guestAccessKey=acd69ea5-6be4-4e56-9486-17878426d1b9&utm_source=For_The_Media&utm_medium=referral&utm_campaign=ftm_links&utm_content=tfl&utm_term=070722
So much for lockdowns, masks, and NPIs saving lives, right?
EDIT: The first link should read “from 2019 to 2020”, not 2021, as not all data are updated yet for every state.
There was no pandemic.
We must avoid using the language of the enemy, chosen to distort.
Covid is unexceptional.
India has a young population, but massive conurbations, pollution.
South Africa has high density townships.
The common cold targets the elderly, particularly those with a history of respiratory infections, comorbidities.
Japan has a high quality Bacillus Calmette-Guérin (BCG) vaccination program, the principal element of tuberculosis control in Japan.
‘This randomized, double-blinded, placebo-controlled trial shows that multi-dose BCG vaccination is safe and prevents COVID-19 with an efficacy of 92%–100% (depending on case definition) relative to placebo.’
‘This clinical trial has several strengths.’
‘…the subjects are from the United States. This is important because all subjects, prior to enrollment, were confirmed by diagnostics and by history to be unexposed to tuberculosis and lacking prior BCG vaccinations. The United States has never had a country policy of neonatal BCG vaccinations.’
‘…..our trial uses a very potent strain of BCG, Tokyo-172. BCG strain differences for other off-target indications are important, and this strain of BCG exhibits some of the highest in vitro potency and is highly immunogenic.’
‘….it is now appreciated that Japan, as a country with mandatory BCG vaccines and as one of the oldest populations in the world, has remarkable resistance to COVID-19’
https://www.sciencedirect.com/science/article/pii/S2666379122002713
‘Our findings suggest that routine infant BCG vaccination coverage in young generation had a significant impact on prevention of local COVID-19 spread in Japan.’
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7419263/
BCG vaccination has limitations, taking a while to provide protection, but if the government wants to protect future population against further viruses, avoid the stupidity of lockdown, a new BCG vaccination program for all infants and the so far non BCG vaccinated could very well be the way to go, using Tokyo-172.