Hi John - THANK YOU so much for the great service you are doing. I notice that India now recommends hydroxychloroquine, which I thought was pretty much discredited. Any idea what is going on there? Is this just another example of India bungling the pandemic, or is there som e value there?
I don't know what the Indian government is thinking with that recommendation. HCQ has been over-investigated for use in COVID-19, and has been shown to be essentially useless for treatment of the disease. In a prior issue--from the end of last summer, I believe--I covered the fact that it was time to leave HCQ behind. Scientists and physicians have largely done so, so I'm not sure why it has been proposed again by the Indian government.
India has an official national Department of Quackery, the Ministry of Ayurveda, Yoga, and Naturopathy, Unana, Siddha, and Homeopathy. (AYUSH). They also recommend ghee and several mixtures of herbs to treat COVID-19. So ... yeah, don't count on their disrecommending a remedy just because it is nonsense.
It does seem increasingly clear that vaccination largely prevents infection, not just symptomatic disease. But this seems to get conflated with the question of asymptomatic transmission. Obviously, no infection means no transmission. But how strong is the evidence that breakthrough infections, particularly asymptomatic breakthrough infections, are less transmissible?
If vaccination essentially eliminates, or at least greatly reduces, the risk of asymptomatic transmission, that's great. But does it?
Good question. I think it’s fairly obvious at this point that the vaccines limit transmission, but that’s at a population level. It is somewhat difficult to interrogate just how much of an effect vaccination may have on transmission from asymptomatic “breakthrough” cases. But I have to note here that I don’t really think of these as breakthrough cases. These aren’t really cases at all, in my opinion. They represent cases that have been prevented, because there was no disease. On the other hand, asking if they are transmission-competent is reasonable.
The overall feeling that I have from the literature is that there is a substantial reduction in both the frequency of asymptomatic infections in vaccinated people, as well as a substantial reduction in the frequency of asymptomatic infections that are competent for transmission of virus. Asymptomatic infections were already thought to be meaningfully less efficient at transmitting, even in the absence of vaccination. With vaccination, there is evidence that a meaningful reduction is achieved in transmission-competency of asymptomatic infections. The problem is that it is very early on in the study of this question, so I do not feel entirely confident putting numbers on it.
On the whole, it’s clear to me that there is an effect of vaccination in both reducing the frequency of asymptomatic transmission as well as reducing the odds of transmission of asymptomatic infection. What I can’t tell you is the magnitude of those effects.
In case you hadn't seen it -- super interesting new study of autoimmunity in COVID patients: https://www.nature.com/articles/s41586-021-03631-y
That IS indeed interesting. I’m going to give it a read—I sort of unplugged completely during my vacation.
Hi John - THANK YOU so much for the great service you are doing. I notice that India now recommends hydroxychloroquine, which I thought was pretty much discredited. Any idea what is going on there? Is this just another example of India bungling the pandemic, or is there som e value there?
https://www.mohfw.gov.in/pdf/RevisedguidelinesforHomeIsolationofmildasymptomaticCOVID19cases.pdf
Thank you for commenting!
I don't know what the Indian government is thinking with that recommendation. HCQ has been over-investigated for use in COVID-19, and has been shown to be essentially useless for treatment of the disease. In a prior issue--from the end of last summer, I believe--I covered the fact that it was time to leave HCQ behind. Scientists and physicians have largely done so, so I'm not sure why it has been proposed again by the Indian government.
India has an official national Department of Quackery, the Ministry of Ayurveda, Yoga, and Naturopathy, Unana, Siddha, and Homeopathy. (AYUSH). They also recommend ghee and several mixtures of herbs to treat COVID-19. So ... yeah, don't count on their disrecommending a remedy just because it is nonsense.
It does seem increasingly clear that vaccination largely prevents infection, not just symptomatic disease. But this seems to get conflated with the question of asymptomatic transmission. Obviously, no infection means no transmission. But how strong is the evidence that breakthrough infections, particularly asymptomatic breakthrough infections, are less transmissible?
If vaccination essentially eliminates, or at least greatly reduces, the risk of asymptomatic transmission, that's great. But does it?
And how do variants factor into all of this?
Good question. I think it’s fairly obvious at this point that the vaccines limit transmission, but that’s at a population level. It is somewhat difficult to interrogate just how much of an effect vaccination may have on transmission from asymptomatic “breakthrough” cases. But I have to note here that I don’t really think of these as breakthrough cases. These aren’t really cases at all, in my opinion. They represent cases that have been prevented, because there was no disease. On the other hand, asking if they are transmission-competent is reasonable.
The overall feeling that I have from the literature is that there is a substantial reduction in both the frequency of asymptomatic infections in vaccinated people, as well as a substantial reduction in the frequency of asymptomatic infections that are competent for transmission of virus. Asymptomatic infections were already thought to be meaningfully less efficient at transmitting, even in the absence of vaccination. With vaccination, there is evidence that a meaningful reduction is achieved in transmission-competency of asymptomatic infections. The problem is that it is very early on in the study of this question, so I do not feel entirely confident putting numbers on it.
Much of what I’ve summarized here is found in this review paper, which I find to be a great resource on questions of whether the vaccines can impact transmission: https://academic.oup.com/ofid/advance-article/doi/10.1093/ofid/ofab259/6278371
On the whole, it’s clear to me that there is an effect of vaccination in both reducing the frequency of asymptomatic transmission as well as reducing the odds of transmission of asymptomatic infection. What I can’t tell you is the magnitude of those effects.
Happy Shavuot, enjoy your cheesecake and your vacation.
Thank you! Likewise, if you celebrate.
Doctor Leana Wen agrees with you about the mask thing: https://www.washingtonpost.com/opinions/2021/05/13/cdc-mask-rules-vaccination-leana-wen/
Dr. Wen is both a physician and a participant in a Janssen clinical trial (one vs. two doses).