Listening to Dr. Fauci’s portion of the Covid 19 response team briefing on March 5, 2021 on MS-NBC gives the wonderful experience of being taught by a world-class scientist. He suggested some homework, reading an article by John P Moore, PhD. (JAMA 2021 published March 4, 2021). I will attempt to summarize the key points Dr. Moore makes.
Dr. Moore notes that South African and Brazilian variants (B.1.351 and P.1, the antibody and possibly vaccine resistant variants) have “sequence changes in key positions suggesting that they arose under neutralizing antibody selection pressure within people infected or previously infected with SARS-CoV-2. Unusual variants have been seen when the virus replicates at high levels for prolonged periods in immunocompromised individuals.”
He goes on to state that while a strong neutralizing antibody response suppresses virus replication, and a weak response does little to suppress replication, “neutralizing antibodies of intermediate potency are thought to cause the virus to evolve and create ways to escape the constraint on its ability to replicate.”
The “combination of a high virus replication rate within an individual (a high viral load) and a suboptimal level of neutralizing antibodies is the exact environment in which resistant viruses are considered likely to emerge and spread.”
Ominously, the B.1.351 variant was found (in lab experiments) to be partially resistant to neutralizing antibodies induced by 2 doses of the Pfizer mRNA or the Moderna mRNA vaccine. (Implication: don’t feel free to do what you want after 2 doses)
In 2 reports, single dose Pfizer vaccine serum antibodies could not neutralize B.1.351 at all.
Vaccines are less effective during the period between the first and the second dose, and when people are infected in this interval, “the virus can replicate in the setting of a suboptimal of neutralizing antibodies, a situation in which resistant variants may emerge”.
This argues for a short period between the 2 doses of Pfizer or Moderna, which is not the policy in the UK, where a variant of B.1.1.7 (the original is more infectious but not vaccine resistant) containing the E484K substitution in the S (spike) protein has been detected. The E484K substitution is considered a hallmark of neutralizing antibody resistance.
The single-dose Johnson & Johnson vaccine raises the concern that resistant viruses will arise in J&J vaccine recipients if the efficacy of the single dose “wanes over time”. As for giving a 2nd dose of the J&J vaccine, there is a possibility that antivector immunity (to the adenovirus that carries the antigenic material) compromises the efficiency of a second, identical adenovirus dose. Unlike the J&J and the AstraZeneca, which use the same adenovirus vector for each injection, the Russian Sputnik V uses different adenovirus vectors for each injection, and reportedly has higher efficacy.
The concept of “original antigenic sin” is a scenario in which a redesigned vaccine (eg to go after the E484K sequence change) “boosts only the original neutralizing antibody rather than eliciting a new set of antibodies that are intended to target the new virus variant.” Experiments are needed to determine if this applies. If it applies, it would complicate making upgrades to the vaccines we have now.
Thank you, Dr. Fauci, for this learning experience.
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Statins for Primary Cardiovascular Disease (CVD) Prevention: Time to Curb Our Enthusiasm A Habib, M Katz, R Redberg JAMA Internal Medicine published online 8/23/22.
This editorial is a follow-up to Redberg’s 2017 editorial: Statins for Primary Prevention: The debate is intense, but the data are weak. It examines the updated USPSTF recommendations on the use of statins for primary prevention.
The authors note that “there is uncertainty regarding the net benefit to risk ratio of using statins to reduce LDL among persons without CVD (primary prevention).”
One trial (PROSPER) only enrolled older individuals between 70 and 82 years of age: new cancer diagnoses were more frequent in patients on pravastatin than on placebo (1.25); stroke risk was unaffected.
The updated evidence synthesis found that statins yielded a smaller (than the 2016 synthesis) reduction in all-cause mortality (0.92 vs 0.86 in 2016); the benefit for CVD mortality was not statistically significant. 19 of the 22 trials included were industry sponsored. The USPSTF no longer recommends the use of low-intensity statins, since the industry trials were mostly-fixed dose, and 12 of 22 used moderate intensity statins. The authors note that “this change is unfortunate for patients because the frequency of adverse effects increases as the statin dose increases”.
The authors of the editorial dryly note that “The USPSTF recommendations should be considered in the light of a meta-analysis, published in 2010, which included only trials that enrolled patients receiving high-risk primary prevention; this study showed no benefit on all-cause mortality with statins”. (this was a meta-analysis of 11 randomized controlled trials involving 65,229 participants).
Inclusion criteria across studies were heterogeneous and mixed patients with (secondary) and without (primary prevention) heart disease. Since statins have an established role in secondary prevention, this would inflate statins’ benefit.
Individual participant level data of the statin trials is housed at the “cholesterol treatment trialists collaborative” at Oxford University; researchers are not allowed to examine the patient-level data from 24 trials comparing statins to a control group.
The guidelines advise using the American College of Cardiology/American Heart Association pooled cohort equations to stratify risk. The cut points of 5, 7.5, 10, and 20% are arbitrary; the PCE is based on mostly white males enrolled between 1968 and 1990 and does not reflect decreases in rates of CVD due to reduced rates of smoking, shifts in dietary patterns and exercise, and blood pressure control. The risk estimates are inflated. The higher the “risk”, the more the patient will be urged to take a statin.
The USPSTF concluded statins did not have any statistically significant harms, but myalgias are commonly seen, and diabetes risk is increased. The authors note that “it is prudent to keep in mind that although the purported benefits of statins will accrue to a few patients in the future, everyone prescribed a moderate-intensity statin is at risk immediately for the harms. Consideration of adverse effects is especially important for a primary prevention drug, which is prescribed to healthy people who feel perfectly well.”