• We are now engaged in an experiment to see how vaccination, increased exposure, and the new variant interact with each other.
  • Vaccination effectiveness and breakthrough infections updated and explained.
  • Why vaccination benefits others too.
  • Do we need boosters?

Hi there fellow guinea pigs! The experiment we are now a part of seems to be one of eliminating all restrictions with plenty of a new mutant circulating among a highly vaccinated population in the summer.

The hypothesis is that we will end up with ‘hybrid’ immunity consisting of vaccinated and infected people who together will make it tough for the virus to find anyone without immunity, and so be ready for the forthcoming winter.

The whole world is now be watching the UK to see how we do. Initially it seemed to be going rather well, but within weeks of ‘Freedom Day’, the downward trajectory in cases and admissions was reversed.

Oh Dear!

So, we are now in a bit of limbo with people becoming ill due to infection and breakthrough infections. The graph (above) shows the increasing number of positive tests, and below the number of hospitalisations.

Thankfully, this wave is having less impact on illness than before, but there remains a steady 900 or so daily admissions, with 6,900 people in hospital and 900 in intensive care. Right now, levels seem about steady, which is a new phenomenon.

My local hospital has 40 patients with COVID19, which might not seem much until you consider it it a ward and a half of additional patients. The smaller peak shows how vaccination has made a big difference – but it was never promised to be 100%. So let’s have a closer look at what’s happening….

The experiment

The results of this experiment will be blurred by quite a few confounders. For one thing, for many people “Freedom day” on the 19th July made little difference. Many remain cautious. Wearing masks is still common and mandatory on public transport and in many shops, many people are getting out and about less than they did pre-pandemic. Also, schools are out for summer holidays and this was a big driver of positive tests before the end of term.

For others, its holiday and party time! No doubt there will be infections consequent on large numbers of people in intimate contact as well as the direct immune impact of alcohol, drugs, smoking, staying out late and having fun.

The Boardmasters event in Cornwall led to nearly 5,000 cases in the 50,000 attendees over 5 days. This is despite efforts to screen out the non immune.

In terms of the experiment, this is exactly what would be expected as over 75% of those testing positive were under 25 and there are no reported increase in significant illness in terms of admissions, but there will be some attendees who might regret going. Most won’t, but persisting covid symptoms will cause a longer hangover for a few.

The big difference now is vaccine uptake – the UK situation is shown below with high vaccination rates in the older groups towards the top and the lower, but increasing rates in younger groups now getting out. This means that there remains plenty of unvaccinated young people, plenty of viral spread, and breakthrough infections in those not fully protected from vaccination. According to the ONS. over the last month, most infections have been in the younger age groups.


In Scotland, where schools returned last week, daily cases have risen from 800 to 3,200, though schools may not be the whole issue. Of course, repeat testing at schools will generate more cases, though not many more patients.

That hospitalisations remained lower during this wave when compared to those previous, is good news and means that community immunity has made a big difference, whether acquired through infection or vaccination. So lets have a look at that…..


Tests can now tell the difference between vaccine and infection based immunity. Based on such testing of blood donors, 97.5% of the adult population now have antibodies to COVID-19 from either infection or vaccination compared to 18.0% of them have antibodies from infection alone, as show below.

(BLACK = vaccine immunity, RED = immunity from infection)

I get the feeling that blood donors are likely to be a admirable healthy bunch, so this in not the whole picture, but is certainly encouraging and backed up by antibodies measured randomly by ONS.

Of course, this leads to a rather facile debate concerning which is ‘better’ – natural (wild) versus vaccine immunity. Immunity after wild infection depends on the level of severity (and thus immune response) to infection while the immunity from vaccination is focused on the spike protein which is less broad but more consistent. It is intuitive to feel that immunity after natural infection will be more comprehensive, and according to this detailed study, this may be correct, but it is certainly a bigger roll of the dice.

Vaccination wins hands down in terms of individual risk of significant problems.

Vaccination and death

Updates from Public Health England show vaccine effectiveness against mortality remains very high. 2 doses of the Pfizer vaccine gives 95 to 99% protection against death and 2 doses of the AstraZeneca vaccine 75 to 99%. The UK Government calculate that 84,600 deaths and 23,395,00 cases have been prevented by the vaccination programme – and counting. The numbers coming from a model which compares the vaccine plus other measures against the worst case scenario of doing nothing at all, so they might be in the right ball park, but are difficult to put an exact number on. The NIH in the USA calculate 140,000 lives saved. Vaccination works!

Sadly, but not unexpectedly, those in poor areas are four times more likely to die with COVID19 than those better off. This is partly explained by lower levels of vaccination as well as all the various burdens carried by the poor.

Vaccination after infection

For anyone already having had an infection and considering vaccination, food for thought comes from this real life study from Oxford. 14 days after two AZO vaccines effectiveness was 88% among those with prior infection versus 68% in those without; and 93% versus 85%, respectively for Pfizer. In other words, it might make sense to have the vaccination even if you have had prior infection. Perhaps having one jab would do, as in Italy and France.

Another study describes the side effects of vaccination after infection and suggests that most of the side effects are after the second jab, and more with AZO vaccine. In the UK, we are rather behind the curve on this. A single vaccination for those who have had a proven infection would seem reasonable.

Infection after vaccination

Breakthrough infections have made the news, and an Israeli study of healthcare workers has been widely misquoted by anti vaccine groups despite positive PCR results in only 39 of 1497 vaccinated health care workers. There were no admissions, but symptoms persisting at 6 weeks in 19% of those infected. That represents a breakthrough rate of 2.6%. Interestingly all infections were caught from unvaccinated contacts, mostly at home.

Finding out the real rate of breakthrough infections is difficult, and the outcomes are open to interpretation as described in this excellent article in the New Yorker on the Provincetown outbreak in the USA. There, widespread celebrations led to an outbreak mainly in those vaccinated. When most people are vaccinated, this will always be the case.

Yet, this American study of 43,000 people with COVID19 infection showed that the unvaccinated are 4.9 times more likely to get infected, and 29 times more likely to become hospitalised.


Infection after vaccination will always be a disappointment but the data from trials shows this will happen and while vaccination is a fantastic public health tool, nothing if written in stone for the individual. Why does this take place?

Why me?

Infections are caused by three main factors; your immunity, the virus and the viral load. Let’s have a look at them…..

In terms of our immunity, this Oxford study describes the reduced effectiveness of the vaccine against Delta variant. However, protection remains worthwhile against significant disease and is as effective as the wild Delta infection – critically of course, with far reduced risks.

It may also be the case that immunity wanes with time. Antibody levels do decline with time after vaccination, so infections can take a hold, but when immune memory cells are available, as they are after vaccination or infection, they will drive the production of new antibodies and so prevent serious infection, hospitalisation or death. This study reveals that antibody levels of as low as 3% of the pre vaccination level can still prevent 50% of cases of severe disease which is really encouraging.

Then there is the virus; the turbocharged Delta variant will infect vaccinated individuals, and for many testing will be positive before our pre-armed immunity kicks in to beat off the infection before it takes hold in the majority of cases, but not everyone.

Viral load will have an impact too. There is a big difference in what happens if you inhale 10 viral particles after passing someone in the street and the millions or billions of viruses landing in your upper airways from prolonged closer contact in small spaces, as recently seen in the Provincetown and Boardmasters outbreaks.

Masks offer some protection to others from this, but of course are hardly likely to be commonplace in festivals and other celebrations.

So my vaccinated friends who have experienced symptomatic breakthrough infections have been unlucky in terms of how these three bits of the jigsaw fitted together. The only consolation for them is the extra immunity gained by having the vaccination and the infection. Prior protection from vaccinations has been shown to reduce the risk of severe illness and this thankfully played out for my unlucky chums.

Vaccination for others

A Scottish study in March showed that household members of healthcare workers were 30% less likely to get infected and hospitalised than the close contacts of non vaccinated. This may have changed with the Delta variant, and studies are awaited. Community transmission is another thing and likely to be reduced but vaccination. I hope this is borne out by as time goes by. There is good news too….

While it seems viral loads can as be high in the vaccinated as those not, they drop more rapidly in the jabbed, lead to less symptomatic illness and thus less, but not no transmission.

Vaccination remains the key to pandemic control, more so with less restrictions and there continues to be a big element of getting vaccinated that is about helping others as well as protecting yourself.

Of course, a more direct way that vaccination benefits others is by not getting unwell yourself. This takes the load of family members, carers and the heath service, so well done to everyone who has taken the time and trouble to get protected, both for yourself and those around you.


Boosters will be the next issue. There is little doubt that vaccines remain effective and so far so good for the immunity they provide. In the immunocompromised – that is those who are on treatment with immunosuppressives, cancer medication etc – a booster is likely to be useful. So far, new vaccines are not the issue, just making the most of the present ones.

Interestingly a nasal spray based on the AZO vaccine has proved effective in animal studies and is now being trialled in humans. It may ever be better by increasing production of antibodies which prevent infection getting past the lining of our noses. We shall see. I suspect that would reduce hesitancy even further.

One wonders about the winter, in epidemiological terms, something that starts when the English kids return to schools the week after next, and then the annual migration of about 2,000,000 youngsters to distant universities. Dry cold conditions will facilitate viral transmission, sunshine and Vitamin D levels will be falling, and changes in the immune system make every winter a crisis for the NHS and as struggle for many people who become unwell.

Despite all this, boosters should be reserved for special cases. It would make scientific sense to heed WHO advice and get our spare, indeed hoarded vaccines to where they are needed. The lack of political intelligence is driving a free market in vaccines, coupled with profit driven enterprise, patents and intellectual rights which all are moving us further away from vaccinating the world.

In the meantime…

It remains as important as ever to keep your immune system in good order. Good food, exercise, sunshine and Vitamin D, keeping mentally and physically active, keeping weight down, avoiding sugar, minimising alcohol and staying as content as possible during these troubled times reduces not only the risk of COVID19, but many other illnesses too. Plus, just feeling so much better!

As the winter approaches all this becomes more important, as I suspect this will not all be over this winter, though maybe by the next. For me, mask wearing in crowded indoor places, practical physical distancing and making the most of each day will continue to define my daily experience during these difficult and incredibly interesting times.

Any Questions?

If you have any questions, comments or feedback, do feel free to leave them in the comments section at the end of the post and I’ll get back to you as soon as I can.

Many thanks for reading my post.

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