So, just one week later and highly-vaccinated (57%, 70% adults) Miami-Dade cases are now up 115%. By now the Delta mutant has probably taken over. The good news is that hospitalizations are only up 3%. In the past, a rise in hospitalizations immediately followed a rise in cases. Unfortunately, Florida stopped posting deaths per county, so I have no data on this. Is this on purpose (paranoid)?
Compare this to Clark count, NV which has also had a surge the past four weeks. Also a party county with a little over 2 million people. Slightly younger average age than Miami-Dade. The big difference is their vaccination rate is only 40% with 49% for adults. Their hospitalization rates also tend to immediate follow cases. In this surge, hospitalizations have gone up 63%.
This seems to be following the pattern in the UK and Israel. In highly vaccinated areas, cases are rising dramatically due to the Delta variant but hospitalizations and (maybe) deaths are not.
I’m basically in favor of unmarked vans driving around at night, picking up unvaccinated people, and giving them a little J&J. Despite what I think of my maximalist view here, even I’m not in favor of summary executions of the unvaccinated. Perhaps because of this, I read Hugh’s post as “they shouldn’t be able to have a life”, ie, shouldn’t be able to go out and enjoy themselves and potentially infect others. Not, “they should be killed.”
Some good news about naturally acquired immunity and the Delta variant:
Antibodies after mild covid-19 last for at least a year and also bind the new Delta variant
It’s in Swedish, but Google translate does a good job.
The COMMUNITY study, which examines long-term immunity after covid-19, has now followed participants for a year and sees that the vast majority still have high levels of antibodies one year after infection. It has been investigated whether the antibodies bind both to the original virus and to a number of new variants, including Alpha (formerly called B 1.117) and Delta, which are currently spreading in Sweden and Europe. The results suggest continued good protection one year after natural infection.
By examining the study participants as regularly as every four months, we have collected unique data that shows the course over a year. In summary, we can say that we see a generally good antibody response one year after mild covid-19. One uncertainty has previously been whether the immunity after natural infection of the original virus also protects against the new virus variants, such as Alpha and Delta. It is reassuring that we see that the antibodies also bind these more contagious virus variants, says Charlotte Thålin, specialist doctor and responsible researcher for the COMMUNITY study at Danderyd Hospital.
The study, published in the New England Journal of Medicine, confirms headline findings given by Public Health England in May about the efficacy of COVID-19 vaccines made by Pfizer-BioNTech and Oxford-AstraZeneca, based on real-world data.
Wednesday’s study found that two doses of Pfizer’s shot was 88% effective at preventing symptomatic disease from the Delta variant, compared to 93.7% against the Alpha variant, broadly the same as previously reported.
Two shots of AstraZeneca vaccine were 67% effective against the Delta variant, up from 60% originally reported, and 74.5% effective against the Alpha variant, compared to an original estimate of 66% effectiveness.
Effectiveness after one dose of vaccine (BNT162b2 or ChAdOx1 nCoV-19) was notably lower among persons with the delta variant (30.7%; 95% confidence interval [CI], 25.2 to 35.7) than among those with the alpha variant (48.7%; 95% CI, 45.5 to 51.7); the results were similar for both vaccines. With the BNT162b2 vaccine, the effectiveness of two doses was 93.7% (95% CI, 91.6 to 95.3) among persons with the alpha variant and 88.0% (95% CI, 85.3 to 90.1) among those with the delta variant. With the ChAdOx1 nCoV-19 vaccine, the effectiveness of two doses was 74.5% (95% CI, 68.4 to 79.4) among persons with the alpha variant and 67.0% (95% CI, 61.3 to 71.8) among those with the delta variant.
CONCLUSIONS
Only modest differences in vaccine effectiveness were noted with the delta variant as compared with the alpha variant after the receipt of two vaccine doses. Absolute differences in vaccine effectiveness were more marked after the receipt of the first dose. This finding would support efforts to maximize vaccine uptake with two doses among vulnerable populations.
So while there is some reduced efficacy, this study doesn’t suggest a large drop off. Though, there does appear to be a bigger difference in protection provided to people who have only received one dose.
I actually saw the Public Health England data on a YouTube video that was put out by the MedCram channel, which I’m becoming a fan of. My own pull it out of my rectum guestimate across all major vaccines is that, generally, a full course of the vaccine (2 doses for mRNA and one dose for J&J) is probably going to show a range of 65 - 90% efficacy, with the mRNA vaccines probably being more efficacious at both preventing infection but all major vaccines being generally effective at keeping you out of the hospital. They’re still obviously collecting data, but that seems to be the broader picture.
Here is a terrific analysis of the recent Israeli data that is making the rounds showing decreased efficacy of vaccines vs. Delta.
The author is Jeffrey S. Morris, PhD, Professor and Director of the Division of Biostatistics at the University of Pennsylvania’s Perelman School of Medicine.
The article is pretty dense, but very informative and the author does a nice job walking through things step by step. It’s worth the read. Long story short, the headlines claiming only 60-70% efficacy vs. Delta are misleading as the data are not stratified by age. When doing an apples to apples comparison of age groups the Pfizer vaccine shows the following efficacy:
In conclusion, as long as there is a major age disparity in vaccination rates, with older individuals being more highly vaccinated, then the fact that older people have an inherently higher risk of hospitalization when infected with a respiratory virus means that it is always important to stratify results by age; if not the overall efficacy will be biased downwards and a poor representation of how well the vaccine is working in preventing serious disease (the same holds for efficacy vs. death).
Even more fundamentally, it is important to use infection and disease rates (per 100k, e.g.) and not raw counts to compare unvaccinated and vaccinated groups to adjust for the proportion vaccinated. Use of raw counts exaggerates the vaccine efficacy when vaccinated proportion is low and attenuates the vaccine efficacy when, like in Israel, vaccines proportions are high.
This is not just an issue of making vaccines look worse than they are … any summary computing “proportion of hospitalized that are unvaccinated” that covers a period of time in which the proportion vaccinated was low can be similarly misleading, especially if there was a massive Covid-19 surge during that time periods. For example, computing total proportion of hospitalized covid infections in the USA from unvaccinated individuals while aggregating over the entire 2021 (January to present), a time periods that includes the early months in which virtually all USA residents were unvaccinated and there was a massive winter surge, will be similarly misleading. Thus, these artifacts can be used by some to make the vaccines look better than they in fact are, e.g. any report suggesting things like 99.9% of hospitalizations are from unvaccinated when covering a long period of time like this.
The bottom line is there is very strong evidence that the vaccines have high efficacy protecting against severe disease, even for Delta, and even in these Israeli data that on the surface appear to suggest the Pfizer vaccine might have waning efficacy. This is clearly evident if the data are analyzed carefully, and agrees with all other published results to date from other countries.
A key amino-acid change might underlie the coronavirus variant’s ferocious infectivity.
Shi’s team and other groups have zeroed in on a mutation that alters a single amino acid in the SARS-CoV-2 spike protein — the viral molecule responsible for recognizing and invading cells. The change, which is called P681R and transforms a proline residue into an arginine, falls within an intensely studied region of the spike protein called the furin cleavage site.
Researchers are also beginning to join the dots between P681R and Delta’s ferocious infectivity. Shi’s team found that, in cultured human-airway epithelial cells infected with equal numbers of Delta and Alpha viral particles, Delta rapidly outcompeted the Alpha variant, mimicking epidemiological patterns that have played out globally. But Delta’s advantage disappeared when the researchers eliminated the P681R change.
Bar graph halfway down the page shows an eight-fold risk reduction for symptomatic infection (consistent with the vaccines having ~88% effectiveness at preventing symptomatic infection), and a 25-fold risk reduction for hospitalization (consistent with 96% effectiveness at preventing severe infection).
My biggest concern is getting an asymptomatic case and passing it on to my unvaccinated-because-too-young kiddo. I understand that there’s a data availability problem there, but it’s disappointing that there haven’t been any randomized tests that give us some sense of how well the vaccines prevent that (assuming we don’t.)
Table here showing effectiveness of the Pfizer vaccine against asymptomatic, symptomatic-but-not-hospitalized, and hospitalized cases broken out by the four main variants:
If there are people in your life who are vulnerable to infection (e.g. your too-young-to-vax kid), it’s probably wise to avoid specific high-risk activities.
