Vigilance Remains Key
For the remains of Covid-19 and for new zoonoses waiting to jump to humans
In the USA and especially Germany, Covid-19 remains a problem. In France numbers are coming down from a high and in Tunisia they are going up a little from a very low. I will probably still wear a mask while travelling on a German train. Because what are a few hours of discomfort compared to a lifetime of debilitating diseases (see my remarks in the recent months).
As Covid-19 is steadily, if not too slowly, becoming an ever-present nuisance, other viruses are waiting to jump the species barrier or have already done so. A recent article in Wired (via ars technica, PDF) is essentially telling us that our (not mine though) insatiable hunger for everything chicken is driving the next pandemic.
(As a side note: It is mostly irrelevant whether SARS-CoV-2 originated in a lab or in bats because even the lab virus came from bats originally; the recent warming-up by US government agencies of two-year old knowledge has everything to do with preparations for a cold war between the US and China, with scientific credibility as collateral damage.)
A note to the graph lines looking smoother: As data are getting scarce, numbers tend to be less stable and thus fluctuate more. The resulting lines, on which every data point represented the average of 7 prior days, are wiggly. I have therefore extended the average to the prior 14 days. This makes the lines look smoother and lessens the extreme outliers.
A recent article in ars technica (PDF) points at yet another way the SARS-CoV-2 virus can affect organs other than the initial targets. This finding is a lesson for the millions who are still refusing the vaccine.
It was an observational study, meaning that researchers merely looked at historic health data rather than proactively recruiting study participants. The former approach has access to millions of participants but an individual's health data can only be as good as what was entered into the health provider database.
In the latter approach, which is usually done in form or a case-control study, data accrual can be tailored to a specific research question. However, case control studies are expensive and the number of participants in such a study does often not exceed 1000.
In this specific research question, Covid-19 and the risk of stroke, other factors that could also cause stroke (so-called co-morbidities) could only be taken into account if they had been in the patient records or if they had been phrased in a way that could be easily understood. In a classical case-control study, patients would have given a questionnaire that would have asked them about all of the conditions that are known to raise stroke risk.
The uncertainty about co-morbidities weakens the validity of the outcome (also called statistical power). On the other hand, having access to data of 1.9 million patients infected with SARS-CoV-19 adds an immense amount of statistical power that a case-control study cannot ever deliver.
In a nutshell, the study looked at data from 1.9 million people who had Covid-19. Of them, roughly ~14 000 had a heart attack, stroke, or another cardiac event following their Covid-19 disease.
Now, the researchers grouped these 14 000 into those with and those without vaccination and found that being fully vaccinated reduced the risk of having a major cardiac event by about 41 percent, while being partially vaccinated reduced the risk by about 24 percent.
Take-home message: unvaccinated people are faced with a higher risk of stroke or heart attack after they get over Covid-19.