Testing for Covid-19 and Herd Immunity

Testing for Covid-19

Why test people?

There are two different reasons you might want to test people:

    – to discover if they currently have the virus (have the relevant antigens), they are “a Covid-19 case” / “infectious”,

    – to discover if they have been exposed to Covid-19 at some point in the recent past (have the relevant antibodies)


i) Are you a Covid-19 case?

There are two different types of test currently being employed to determine whether someone is “a Covid-19 case”, “PCR tests” and “Lateral Flow tests”.

PCR tests

PCR tests can detect extremely small amounts of virus RNA in a sample.

This means they can return a positive result, even if the person from which the sample is taken is no longer in the slightest bit ill or infectious,

– they may have been infected two or three months previously, have completely recovered, long since ceased to be infectious and be no danger to anyone, but the PCR test detects small traces of, possibly dead virus in their body, and so returns “positive”. 

This person will then be told to isolate immediately, along with all their immediate contacts. 

Testing positive for two months solid via PCR tests led to three students being refused permission to leave Italy:


If you would like to read a full explanation of how the PCR test works, here is a really good one:

PCR positives: what do they mean?

The PCR test was never meant to be used in the way that the UK government has been using it, that is…  to determine

 “How many active cases of Covid-19 do we have in the population?”

 – it will always indicate there are a lot more than than there really are, because people continue to test positive for weeks, often months after they have fully recovered and ceased to be infectious.

The UK government has been repeatedly warned that the PCR test is entirely inappropriate for the purpose they are using it, by many people, including by those who actually designed and developed it, but appears not to care.

PCR tests require laboratory equipment to perform them, so will normally take at least a day to get results.


Lateral Flow tests

Lateral Flow tests, unlike PCR tests, need quite a high viral load to be present in order to return a positive result.

Arguably they are therefore a better test to use if you wish to know “who is infectious”.  I would certainly argue this anyway.

(When the government talks about “Covid-19 cases”, I would suggest most people think they are talking about “infectious people”).

If you have a low viral load you may still become infectious at some point in the future, if for example you have recently become infected with Covid-19,

– alternatively you may have had it several weeks or months previously, and so have gone considerably past the infectious stage.

If you would like to read a little more about Lateral Flow tests, this is an excellent place to start:


The best Lateral Flow tests in use currently detect over 95% of individuals with high viral loads, and there is minimal difference between the ability of the test to pick up viral antigens in symptomatic and asymptomatic individuals,

 – in other words they work pretty well whether you have symptoms or not.

A major advantage of these tests is that they return results in just 20 or 30 minutes. 

No requirement to send samples off to laboratories.


ii) Have you been a Covid-19 case, have you had Covid-19 and recovered?

Antibody tests are not currently widely available, only people in certain professions have access to them:


The tests require a blood sample to be taken and analysed in a laboratory, and have a number of limitations,

 – you might have antibodies but not be immune to getting infected with the virus,

 – or not have them, and be protected by other defences present in the human body (T cells etc)

Despite what the UK government’s advisers like to tell people, during “Corona virus Special Announcements”,

 – the number of people who currently have antibodies in the population (roughly 10% in January 2021)

 – actually tells us very little about the level of herd immunity we have built up in our population.

It is certainly not true to say that the other 90% of people, those who don’t have any antibodies present in their blood, are at great risk of contracting Covid-19 and becoming seriously ill and dying. 

But they still say it. 

Please don’t take my word for this, read this explanation in the British Medical Journal


So they are deliberately lying to us, presumably to maintain the highest possible level of fear in the population, and as a result, vaccine uptake.

At least I presume that’s why they are doing it. Am I being too generous?



The second lie that is now frequently told in public by government advisers, eg Dr Hopkins, 25/01/2021 is this:

“Herd immunity is a word we use to describe the immunity we get from vaccination,” she told the briefing on the above date

“One in 10 people having immunity is far away from where we need to be.” 
(This would be true, except almost certainly far more than 10% of us now have some form of immunity to Covid-19, for the reasons outlined in the http://www.bmj.com article above)

Dr Hopkins said the biggest job was to roll out vaccination to individuals who are at a high risk of death and hospitalisation, and then to the rest of the population.

“Once we’ve done that, then we will have herd immunity,” she added.



Dr Hopkins clearly lied.  The definition she put forward is an entirely false definition of herd immunity.  

Herd immunity is simply the immunity in the general population to being infected, or re-infected with something, in this case Covid-19,

 – and can be built up in a number of ways, primarily through having been infected and recovering, or being vaccinated.

The reason Dr Hopkins perhaps felt empowered to tell this blatant lie…. that only vaccination builds up/leads to herd immunity,

 – is presumably because the World Health Organisation recently changed it’s definition of herd immunity, to claim exactly this,

  – herd immunity can only be acquired through vaccination. 


Here is the Oxford English dictionary definition:

“herd immunity
  1. resistance to the spread of an infectious disease within a population that is based on pre-existing immunity of a high proportion of individuals as a result of previous infection or vaccination.

This is the widely accepted definition in the medical world.

So why did the World Health Organisation briefly try to change it to state that herd immunity could only be acquired through vaccination ?


(Interestingly it now appears to have changed it back, and acknowledges that herd immunity may also be acquire through exposure to a virus,

 – unfortunately “Dr Hopkins” didn’t appear to be aware of this:


To be fair to Dr Hopkins, the WHO does change its mind on almost everything connected to Covid-19, on a very regular basis… it can be hard to keep up)


Presumably this redefinition was also part of “the global push” …to encourage as many people as possible to get vaccinated.

If so is this ethical?  Redefining medical terms to encourage people to get vaccinated?  Essentially…. just blatantly lying ?


We live in strange and disturbing times. 

As discussed in other articles on this site,

– as long as lies serve to increase fear levels in the population, our government, and its advisers, now appear to believe telling lies is completely acceptable, in fact, to be encouraged.