Sunday, September 26, 2021

What is the scoop on boosters?

Are you feeling confused about Covid vaccination boosters? Join the crowd. So, it appears, is almost everyone in Washington (and everywhere else).

What do we know? What should you do?

We know that the mRNA vaccines remain very effective at preventing serious infection, though it is certainly possible for vaccinated people to catch and spread the virus.

While the Pfizer and Moderna vaccines were in a dead heat (95% vs. 94%) in effectiveness based on the original trials, the Moderna vaccine seems to hold up better. This may be because it uses a higher dose (100 vs. 30 micrograms) and/or because the longer time between doses (4 weeks vs. 3) is better for developing immunity – the longer the better is true for most vaccines.

A study from the CDC found that while both mRNA vaccines offered 90% + protection for the first 4 months after vaccination, this fell to 77% for Pfizer while staying the same for Moderna.

Pfizer has said that antibody levels increased 3-fold in a small (300 subjects) set of volunteers given a booster 5 to 8 months after their initial series. The use of a booster is also supported by data from Israel, where immunity seemed to fade over time but was restored to 95% by a booster in people 60 and older (Israel used almost entirely the Pfizer vaccine).

Finally, the J&J vaccine was less effective than the two mRNA vaccines, but one small study found no drop in antibody levels over 4-6 months, and another found that a booster of the same vaccine made antibody levels rise nine-fold.

There has been no testing of using a different vaccine as a booster to one of the three approved in the U.S., but a study done in Britain found that following the Astra Zeneca vaccine with the Pfizer gave much better protection than using the A-Z vaccine alone (and the A-Z vaccine uses similar technology to the J&J shot). It is unlikely that “mix and match” would be harmful.

The FDA recently approved using the Pfizer vaccine booster for select groups, and the head of the CDC advised broadening the groups eligible.

So… what should you do?

If you got the Pfizer vaccine, had no major side effects and are in a high-risk group, get it. It will be free, and the best evidence we have now says it will improve your protection. The side effects of a third shot were similar to those of the first two. If you are young and healthy, I would not recommend it until we have more data.

If you got the Moderna vaccine, you seem adequately protected. When Moderna’s booster is approved, I would follow the same advice: high-risk (including age) yes, otherwise wait.

If you got the J&J shot, talk to your doctor about possibly using the Pfizer booster “off-label.” Since it is now fully approved, he or she can prescribe it if they feel it is indicated.

Prescription for Bankruptcy. Buy the book on Amazon

Friday, September 10, 2021

On "Liquid biopsies" and other screening tests

Coming to a mall near you! Or at your doctor’s office or via direct mail: the chance to have a “simple blood test” to detect very early cancer and perhaps save your life. What is the truth behind the hype?

The term “liquid biopsy” refers to the screening of a blood sample for traces of abnormal DNA that are felt to be the markers of a variety of cancers. These tests were approved by the FDA in 2020 for a very limited purpose: to detect DNA markers of specific subtypes of known cancers that meant the cancers would respond to specific treatments. The tests were meant to identify specific cancer-related genetic changes which could influence patients’ treatment choices or make them eligible to participate in clinical trials.

While that is a lucrative market, what has Wall Street salivating is a much larger potential: offering such tests to everyone, with the promise of detecting cancer long before it caused symptoms. We have been conditioned to believe that early detection = greater chance for cure, and in some cancers this is valid. If everyone had regular colonoscopies, the death rate from colon cancer would fall. Early detection of lung cancer in smokers using low-dose CT scanning has been shown to reduce lung cancer death and regular mammograms reduce death from breast cancer, though in neither of these latter cancers is the screening test “dramatically” effective.

Before we start recommending very expensive “liquid biopsies” for widescale use, it is critical to look at what they will accomplish rather than what they might.

The idea behind screening tests is to look for disease in apparently well people with the expectation that finding and treating disease before symptoms develop will lead to better health and/or longer life. In the case of colonoscopy, the theory has been validated, but this is not always the case.

Example 1: screening for atrial fibrillation (AF). We know that AF, a heart rhythm disorder that is very common as we age, is a major cause of stroke, and that by putting patients with AF on blood thinners we can reduce their stroke risk by as much as 80%. A recently published study looked at using small monitors implanted under the skin to detect episodes of AF that would never be found routinely. They did detect three times as many episodes of AF – BUT – when they treated these people with blood thinners, there was no real difference in strokes or deaths compared to the group not screened. It appears the brief asymptomatic episodes of AF that were found may not be as serious as AF found in routine practice.

Example 2: screening for thyroid cancer. In 1999, Korea embarked on an aggressive national cancer screening program. While ultrasound screening of the thyroid was not initially included, it quickly became a widely used study. As a result, by 2011 the rate of thyroid cancer diagnosis increased 15-fold over the rate in 1993. Thyroid cancer is now the most common cancer diagnosed in Korea. At the same time, the death rate from thyroid cancer did not budge. Almost all of these cancers are low-grade and small, and we have known for 70 years that low-grade thyroid cancer is very common and rarely kills. Thyroid surgery is not innocuous: patients can have vocal cord paralysis, accidentally have their parathyroid glands damaged and usually need to take thyroid hormone for life. All for a disease that would never have bothered them if not found.

SO: before the FDA approves “liquid biopsies” for screening use and before you consent to having one done, we need evidence that these tests not only detect cancers not otherwise easily found, but that finding these cancers will let you live a longer and/or healthier life. Otherwise, I fear, we are going to see your health made worse by extensive imaging studies looking for this possible hidden cancer and your life put at risk by having surgery that you do not need.

Let’s not put the cart before the horse.

Prescription for Bankruptcy. Buy the book on Amazon