Pyser Testing

Vaccine efficacy

Vaccination Doesn’t Add Any Protection to that Gained from Previous Infection – Study

A new study (not yet peer-reviewed) of over 50,000 employees of the healthcare system in Cleveland, Ohio, has found that previous infection provides very robust protection against re-infection and, importantly, that there is no gain to being vaccinated as well.

U.S. Senator Rand Paul tweeted the study’s conclusion: that it means vaccines should be prioritised for the not-previously-infected at home and abroad, not wasted on the already immune.

The confirmation of the protection provided by natural infection is very welcome, as is the finding that vaccinating the previously infected is superfluous. Given the significantly higher risk of adverse events for those previously infected (up to three times higher according to the ZOE Lancet study) and the world shortage of vaccines, there would seem to be a moral imperative to cease vaccinating the previously infected.

The study’s finding is particularly robust because of the large sample size and because there were zero instances of re-infection among the previously infected (both vaccinated and unvaccinated). This was despite the study period beginning at the peak of Ohio’s winter wave, so the unvaccinated had plenty of exposure to the virus. Other studies have found the relative risk reduction offered by previous infection to be 80% against all re-infection and 90% against symptomatic re-infection, so the results in this study were even higher than usually observed.

However, the study’s findings for vaccine effectiveness in the not-previously-infected are much less reliable.

Matt Hancock Reveals Hospitalisation Rate of Indian Variant is Just 1% – Half that of the British Variant

Health Secretary Matt Hancock revealed some statistics in the Commons yesterday about the Delta (Indian) variant: out of 12,383 Delta variant positive tests in the U.K. up to June 3rd, 464 went to emergency care and 126 were admitted to hospital. Of those admitted to hospital, 83 were unvaccinated, 28 had had one jab and three had had both doses.

Keen-eyed readers will spot that 83+28+3 is not 126 – there are 12 hospital admissions unaccounted for. A Department of Health source told the Financial Times‘s Sebastian Payne that nine of these “don’t match to a vaccine status at present” while three were within 21 days of their first dose so didn’t count in any category.

Can we use these figures to make some crude calculations of the severity of the Delta variant?

126 hospital admissions out of 12,383 positive tests gives a 1% hospitalisation rate, or 99% not needing hospital. How does this compare to the Alpha (British) variant?

Last week Public Health England (PHE) released a study claiming the Delta variant had around double the risk of serious disease or hospitalisation compared with the Alpha variant. However, according to the ONS, during the winter peak when the Alpha variant was dominant, around 2% of the population of England was infected with COVID-19 and around 0.04% of the population was being admitted to hospital with the virus each week, giving around 2% of British variant infections leading to hospital admission. This is double the rate for the Indian variant on Hancock’s figures – and furthermore, Hancock’s figures use positive cases, not an ONS population infection estimate, which would reduce the hospitalisation rate for the Indian variant further.

However, what we don’t know, because these are just statistics delivered verbally in Parliament not a proper report (more science-by-press-release), is how many of the 12,383 positive cases are too recent to have led yet to hospital admission. We also don’t know how elderly or vulnerable those in the sample of 12,383 are, or what impact the vaccines are making on the hospitalisation rate.

The figures are of limited use as well in estimating the effectiveness of the vaccines against hospital admission with the Delta variant. That’s because we don’t know what proportion of the 12,383 infected were vaccinated, so we can’t control for that key factor. Having said that, the three versus 83 hospital admissions for fully vaccinated versus unvaccinated seems encouraging.

Overall, this data is very limited. Nonetheless, the fact that the hospitalisation rate even among positive cases is so much lower with the Delta variant now than with the Alpha variant in winter is further evidence that the latest scariant is nothing to fear.

PHE Quietly Revises Down Effectiveness of AstraZeneca Vaccine

The latest Public Health England (PHE) weekly vaccine surveillance report appeared on Thursday (another one is due tomorrow).

I wasn’t holding out high hopes for this instalment, after digging down into the method used the previous week and finding it didn’t control adequately for background incidence (so confounded vaccine effectiveness with natural decline) and applied such brutal adjustments it could turn a 4% effectiveness into a 73% one. It lived down to expectations.

The authors appear still to be working out what exactly their reports are for as each of the three to date presents different information in a slightly different way. While the first was largely a summary of evidence published elsewhere, the second served more as a showcase for PHE’s latest study and focused on effectiveness against symptomatic disease in the over-65s (90%, supposedly). This week, the over-65s are gone and the focus is on effectiveness against the Indian variant. This makes reading the reports quite confusing, as each doesn’t feel so much like an update to the previous one as a stand-alone report on a separate topic.

In between Report 2 (for week 20) and Report 3, a separate PHE study was published on the Indian Delta variant which found the effectiveness of full vaccination against symptomatic Covid reduced from 93% to 88% with Pfizer and 66% to 60% with AstraZeneca when the Indian Delta variant was involved versus the British Alpha variant.

As I noted last week, this 66% effectiveness of AstraZeneca (against the British Alpha variant) was a long way below the 90% in the over-65s claimed in Report 2. It’s probably a sign of how low my opinion is of PHE vaccine studies that I was pleasantly surprised to see this discrepancy actually make an impact on the data presented in Report 3, and you can see below in the AstraZeneca two-doses box (top right) week 20’s “85-90%” has become “65% to 90%” in week 21. There is still no explanation from PHE, however, as to why one of their studies finds AstraZeneca 90% effective against symptomatic infection in the over-65s while another finds it is just 66% effective in all ages. Is this not the kind of discrepancy that should occasion comment from the authors?

Do SAGE Members Calling for Lockdown to be Extended Beyond June 21st Not Believe the Vaccines Work?

So do the vaccines not work then? That’s certainly the impression you’d get from the way various members of SAGE are carrying on, warning of new waves and new variants and the need to delay the end of lockdown even further (completely ignoring the fact that half of America is now open without any problems so far).

As Sherelle Jacobs asks in the Telegraph, why is the debate continuing as though nothing has changed despite half the country – the most vulnerable half – being vaccinated?

Instead of discussing how quickly vaccines could spell the end of restrictions, the commentariat fixates on the risk of another wave as if absolutely nothing has changed. Somehow, despite low deaths, the Indian variant rather than the vaccine has become the game changer.

We have become wearily used to these media interventions from SAGE members in the build-up to key decisions around lockdowns, usually pushing some skewed version of the scientific evidence to frighten the public and pile pressure on the Government to tighten or maintain restrictions. This was bad enough in the autumn before the vaccines were on the scene, but now it leaves you wondering if they know something we don’t about how well the vaccines prevent death and serious disease.

The Government has been continually putting out new research showing how effective the vaccines are, including against the Indian variant, and while I have written on a number of occasions about the shortcomings of these studies, I had been assuming that the vaccines do work, or at least that the Government and its scientists believe they work. With all this talk of third waves and extending lockdown, you have to wonder.

The latest line to justify extending the lockdown is from NERVTAG member Professor Ravi Gupta, who argues for just a few more weeks to let more people get vaccinated, saying there are signs an “explosive” third wave is on the horizon.

Yet according to the latest figures, 51.3% of the adult population has now had one vaccine dose and 31.4% has had two. Over 90% of the over-70s are now fully vaccinated.

ZOE Data Shows Vaccines Cut Hospitalisation Risk by 64% once Infected, but Data on Frail Elderly is Less Positive

Professor Tim Spector, who leads the ZOE Covid Symptom Study, has done a new video update on vaccines, which is worth a watch. The team has also published a new study (not yet peer-reviewed) about the vaccines and their effect on symptomatic Covid.

The data is broadly encouraging in terms of efficacy. (They don’t address safety, though a previous study did. They also exclude the period immediately after each vaccine dose, so the study tells us nothing about any post-jab spike in infections, which is disappointing.)

One interesting finding is that sneezing becomes more common as a symptom of Covid infection after vaccination than beforehand, which the authors suggest could be a result of our immune system reaction changing. They note this could make the disease more infectious owing to the additional aerosols produced.

A concerning finding was that the elderly (over-60s) were up to three (2.78) times more likely to be infected after being vaccinated (with one dose of any vaccine) if they were frail than if they weren’t. This is unsurprising perhaps, but still indicative of considerably lower protection for those already at higher risk from the disease. Furthermore, a quarter of the vaccinated frail elderly in the study who contracted the virus ended up in hospital, which is not a small proportion (though no figure was given for the hospitalisation rate of unvaccinated frail elderly people against which to compare it).

Vaccine efficacy was also reduced in the obese, another high risk group, and those with an unhealthy diet – see charts below. The baselines are people who are also vaccinated and otherwise similar, but without the particular characteristic mentioned, e.g. the point in the top right shows the additional risk of infection that the vaccinated frail elderly have versus the vaccinated non-frail elderly.