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Is there any connection with Covid 19 vaccines and CJD?

By 15/09/2021News

Please see below answers to this now often asked question by prion disease experts:

Ryan Maddox from the US CDC commented on whether there is connection with Covid 19 vaccines and CJD in one of his talks. Thank you to our friends at the CJD Foundation US for sharing this link- Is there any relation between covid 19 vaccine and cjd?

Professor Richard Knight from Edinburgh UK:

“For many people with a loved one diagnosed with suspected CJD it is an emotional time and they are vulnerable. They will be coming for support and any information needs to be accurate. My comments on the particular subject are:

1. I do not know of any evidence that there has been a significant in common increase in CJD numbers since Covid vaccinations began. There are two caveats to that comment. Firstly, there has been a slight, gradual increase in CJD numbers in many countries over the last 20+ years. This is most likely due to better awareness, diagnosis and better recognition of atypical cases. It may well, therefore, be that a slight increase in numbers will be seen in some countries after Covid- but, if this occurs, this will almost certainly just be a continuation of the slight increasing trend that was observed before Covid. Secondly, if there were an increase in cases noted over a short period of time, this might not mean there is a real increase in case numbers-one sees fluctuations in numbers (as one would expect with a relatively rare illness) that need to be averaged out over longer periods. For example, in the U.K., in a particular year, there might be a greater number of cases than usual but then the next year, a lower number than usual. One needs to look at figures over longer periods than a few months or even over just one or two years.

2. One important point is that individuals often look to life events to try to make sense of what has happened to them or their relatives/friends. If something has happened just before becoming ill, there is a strong pull to wonder if that was the cause or precipitant. This is a feature of many illnesses, not just CJD. One needs to look at data over many cases over time to determine if a particular factor might be relevant. Even then, it can be very difficult to decide if a factor is relevant. For example, when we had BSE-related in the U.K., we had illness in some who had occupational connections with cattle and the question was whether this could be the cause of their illness. However, in order to determine this, one needed to know what percentage of the population in general had such occupational connections and then whether illness was affecting a higher proportion of people with such occupations than one would expect by chance. The difficulty with Covid vaccinations is that -at least in the U.K.-around 90% or so of the age group in which sCJD typically occurs have been vaccinated and vaccinated quite recently. Therefore, virtually all sCJD cases presenting now will have had a Covid vaccination in that last few months or so.

3. CJD Surveillance systems are active in most countries and are very interested in finding the cause of sCJD. If, by any chance, Covid vaccinations are relevant, this will be identified and there is no reason why this would be kept secret- indeed, I don’t see how it could ever be kept secret, given the involvement of many clinicians and scientists in many countries who have devoted their professional lives to this subject.

4. Very importantly, if a cause or precipitating factor is suggested, quite aside from the observation, by surveillance systems, of cases to see whether in fact it is, one can make judgements on whether the proposed cause is likely to be relevant. The point here is that there is no good theoretical reason why Covid vaccinations would cause CJD. It is conceivable that such vaccinations might accelerate a pre-existing CJD disease process (note: conceivable ie a possible idea) but, if so, this would be true for many other vaccinations such as seasonal flu vaccines. There is no good evidence that vaccinations in the past have had an effect on CJD. Of course, if a vaccination accelerated a pre-existing CJD disease process, then the person already had CJD and would become ill anyway after a time. And, if this vaccination process was relevant In accelerating illness, then the actual illness would also likely be relevant in accelerating disease. So, given the very much greater risk of Covid, the only sensible move is to be vaccinated. At this point, I should emphasise that there is actually NO good evidence that Covid vaccines have in fact accelerated pre-existing CJD disease. I am just allowing for that possibility as it impossible to exclude it as an unlikely theoretical consideration and we should be as complete and honest as possible in our responses. And that is not the same as saying Covid vaccination causes CJD or increases the numbers of cases, which would occur at just the same rate as without Covid vaccination.”