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24 Nov, 6 tweets, 2 min read
The best COVID questions I got yesterday: 
1. Why did AstraZeneca give volunteers a half dose of vaccine followed by a full dose a month later? And why did that group do so much better than those who receive two full doses? (90% effective vs. 62%) 1/
2. Should prior #COVID19 infection affect your place in line for a vaccine?
3. If a healthcare worker gets vaccinated and develops a fever, does that person stay home from work the next day?
Answer to #1: It was an accident. Researchers were confused when side effects were much milder than expected, so they checked & realized they'd mistakenly given volunteers half of the predicted dose. We don't know why that worked better, but it did. 
reuters.com/article/uk-hea…
One theory: Lower-dose vaccine might be better at stimulating T-cells and antibody production.
Another: the higher dose blunted the immune response against the vaccine's viral vector.
The takeaway: AstraZeneca got really, really, ridiculously lucky.
nature.com/articles/d4158…
Answer to #2: Maybe. COVID survivors are likely immune for 3 months & possibly much longer. But it's a hurdle to test people prior to vaccination. Antibody tests are a good approximation but they're not perfect. Don't expect prior infection to impact rollout in most communities.
Answer to #3: It really depends how much worse things get. Some hard-hit states have allowed infected workers to stay on the job and might not have the luxury of letting people stay home to figure out if the fever is vaccine-related: nbcnews.com/news/us-news/n…

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Matt McCarthy Profile picture
24 Nov
CDC's Advisory Committee on Immunization Practices proposes 4 groups for initial vaccine rollout: 1) healthcare workers (21 million people), 2) other essential workers (87 million), 3) adults with high-risk conditions (>100 million) & 4) adults age ≥65 years (53 million). 1/
The subtext here is that in an effort to mitigate health inequities, "other essential workers" (police, firefighters, teachers) will have access to vaccines before adults over age 65: cdc.gov/mmwr/volumes/6…
EUA of a vaccine is unusual--it's only been done once before (anthrax, 2005)--and some may be concerned about targeting certain high-risk, traditionally-marginalized groups with an experimental product. But CDC is going about this thoughtfully & should be lauded for their work.
Read 4 tweets
Matt McCarthy Profile picture
21 Nov
Common question: If I contract coronavirus tomorrow, what meds would I want? Short answer: Depends where I am. If you sift through all of the breathless #COVID press releases, the only "game-changer" is dexamethasone, a cheap & widely available steroid that saves lives. But... 1/
I would only want it if I'm really sick. Otherwise, it could actually make things worse. Drugs that work in some groups fail in others. Lilly's antibody, bamlanivimab, is weakly effective (maybe?) for patients outside of the hospital but makes things worse for sick patients. 2/
This matters as we think about the vaccine roll out: different groups may respond differently. For example, patients in longterm care facilities (nursing homes, assisted living facilities) may be quite different than the people who actually enrolled in #COVID vaccine trials. 3/
Read 5 tweets
Matt McCarthy Profile picture
18 Nov
Here's a controversial paper that's often referenced during ethics meetings when we discuss how to allocate the limited supply of #COVID19 vaccines. Lead author is Ezekiel Emanuel, a member of Biden's coronavirus task force. Key arguments: 1/
nejm.org/doi/full/10.10…
Frontline health care workers should be given priority "not because they are somehow more worthy" but because they're essential to pandemic response. Younger patients should not be prioritized. Avoid first-come, first-served distribution as it may encourage crowding or violence.
If vaccine supply is insufficient for high-risk patients, consider a lottery. People who participate in COVID research (think of someone who enrolled in a remdesivir trial) should receive some priority.
Read 7 tweets
Matt McCarthy Profile picture
17 Oct
UPDATE: The #coronavirus case fatality rate continues to drop. Here's one reason that doesn't get a lot of attention: We're getting much better at triage. During the first few months, we really couldn't tell which hospitalized patients were going to get worse. That has changed:
Why were we bad at this? Many with #COVD19 suffer from 'silent hypoxemia,' where oxygen levels appear incompatible with life yet patients feel no symptoms. The President may have had a subtle, less aggressive variation of this when he was airlifted to Walter Reed but felt fine.
Vital signs have proven unreliable for effective triage, so we've turned to lab tests for help. One that quickly emerged as a potentially-helpful candidate was interleukin-6 (IL-6), a marker of inflammation that is usually absent (or present in low levels) in blood.
Read 8 tweets
Matt McCarthy Profile picture
16 Oct
This is a stunning and inaccurate claim. Rewriting history is a mistake. Some key points about the #coronavirus surge in New York City:
1. Our stockpiles of PPE were unable to withstand the first wave. We went from using 4k masks/day to 40k masks/day to 90,000 masks/day at the peak & we did not have the stockpiles to keep up.
2. Hospitals had to create I.C.U.s out of operating rooms, procedure suites, and conference areas. We created ventilators out of anesthesia machines and split ventilators to help two patients simultaneously. We redeployed doctors to the ICU who didn't typically work there.
Read 5 tweets
Matt McCarthy Profile picture
16 Oct
NEW: There's an emerging argument that masks don't actually work. It's based on a recent study published by the CDC, which reportedly showed that 85% of mask-wearers contract #COVID19. This is a dangerous mischaracterization of the study. Here's what the work really showed:
CDC looked at 154 adults with symptomatic #COVID19 and compared them to an uninfected control group. Of the patients with #coronavirus, 70.6% reported ALWAYS wearing a mask and 14.4% OFTEN did. From a distance, it looks like 85% of mask-wearers got COVID.
cdc.gov/mmwr/volumes/6…
But you've got to read the actual study. Here's the key detail: COVID patients were twice as likely to have dined at a restaurant. Why does this matter? Because people take off masks to eat. You might report that you ALWAYS wear a mask but we know it comes off when you're eating.
Read 4 tweets

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