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4 Dec, 4 tweets, 1 min read
The controversial argument to continue placebo-controlled vaccine trials after emergency authorization hinges on this idea: The obligations researchers have to volunteers in a trial are distinct from the obligations that physicians have to their patients. 1/
Researchers must always ensure that placebo-controlled trials remain ethically appropriate, and that takes into account a variety of factors, including local transmission rates and individual risk profiles (volunteer age, medical conditions). 2/
The case for continuing these trials is laid out here by NIH bioethicists: science.sciencemag.org/content/early/…
We will likely need multiple vaccines to curb the pandemic; we'll also need more placebo-controlled trials. After an emergency authorization is issued, will anyone sign up?

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Matt McCarthy Profile picture
6 Dec
UPDATE: We've been clamoring to see the vaccine data for months. That will finally happen on Tuesday (December 8), when Pfizer’s info is released to the public. Here are some things I’ll be looking for that were not revealed in press releases: 1/
1. What do we know about the memory T cells of vaccinated volunteers? There’s been a shift in thinking on the role of these immune cells. They may be more important for protection than neutralizing antibodies, which have previously been the focus. 2/
2. Most major adverse events appear within 6-8 weeks of vaccination. (Minor events have a different timeline). After tens of thousands of vaccinations, there does not appear to be a common, severe side effect associated with this vaccine. What about uncommon events?  3/
Read 8 tweets
Matt McCarthy Profile picture
6 Dec
COVID question I've been getting: Why do I need a vaccine when there's a 99.7% survival rate? It's a fair point (and makes for a lively discussion!).
Here is my response: 1/
Survival is an important metric, but it's the wrong one to focus on. Coronavirus is different than anything we have seen before. It causes strokes, it inflames blood vessels. It alters your sense of smell because it gets into your brain. It causes oxygen levels to plunge and.. 2/
you might not even feel it. It causes symptoms that last for months and we don't know why. When someone contracts the virus, I'm not just worried about survival.  3/
Read 6 tweets
Matt McCarthy Profile picture
5 Dec
UPDATE: I’ve been asked to provide guidance to some doctors who are trying to figure out: 1) whether to take a #COVID19 vaccine issued under emergency authorization and 2) what to recommend to their patients.
Here’s my approach:  1/
On December 10, I'll watch the Vaccines and Related Biological Products Advisory Committee discuss Pfizer's data. I have many questions about subgroup efficacy, safety, & memory T cells. I’m confident those will be addressed. Then, fighting the urge to do something, I’ll wait. 2/
We’ll do it all again on December 17th when the same panel meets to discuss Moderna’s data. After that, I’ll speak with colleagues, compare notes, and hash out a recommendation. I'll explain the rationale and my level of confidence in that recommendation. 3/
Read 6 tweets
Matt McCarthy Profile picture
4 Dec
COVID Question: Will vaccination be a yearly thing? Maybe. After the rollout, we'll do surveillance to determine: 1) How long protection lasts and 2) If mass inoculation causes coronavirus to mutate.
It's an RNA virus, and replication is often sloppy, so it could change. 1/
We don't yet know if #coronavirus will behave more like measles or influenza. Both are RNA viruses, but they require vastly different vaccination strategies. Most people are protected from measles by childhood shots; by contrast, influenza requires yearly vaccination. 2/
The difference has to do with how these viruses mutate. Measles has one serotype; influenza has several.  3/
Read 5 tweets
Matt McCarthy Profile picture
4 Dec
Vaccine Dilemma: When should volunteers who received placebo get the real thing? If vaccines are highly effective, it seems unethical to withhold inoculation from people who bravely volunteered for a study. But that’s what some researchers want. 1/
mRNA vaccines are reportedly 95% effective, but it’s possible that number will degrade over time. Allowing volunteers to cross over from placebo to vaccine unblinds these trial and ends the collection of randomized data.
That prevents us from learning crucial information... 2/
...about the degradation of vaccine efficacy, durability of protection, and long-term safety data. Some argue that volunteers who received placebo should be among the LAST to get vaccinated.
This preserves the integrity of ongoing trials. 3/
nejm.org/doi/full/10.10…
Read 5 tweets
Matt McCarthy Profile picture
3 Dec
Question today: A man develops a fever and is diagnosed with #COVID19. How long should his wife quarantine?
After her initial exposure, she is careful to stay six feet away from him, but they live in a small(ish) apartment. 1/
Until recently, the recommendation was for her to quarantine for 14 days. But the CDC just changed guidance and now indicates that 7 days (with a negative test) or 10 days (no test) is also sufficient.
But is it?
Roughly 97.5% of patients will develop symptoms 11.5 days after exposure, so the new recommendation is good, but not airtight. And not all exposures are alike; she lives with the guy. Letting her out of quarantine after 10 days with no test seems unwise and potentially dangerous.
Read 5 tweets

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