Thread by @MonicaGandhi9

of passing the virus to others if you are undetectable on antiretroviral therapy because I marveled CDC (a traditionally conservative public health agency, understandably; they are messaging for nation) would put out such a bold statement even though it was true. For breakthrough

infections after vaccination, I hope I, others have convinced you that these are RARE (0.008%) and even more rare for symptomatic infections. 77 million Americans fully vax against COVID, ~5800 symptomatic & asymptomatic but only 4100 symptomatic so 0.005%
cdc.gov/vaccines/covid…

See that nursing homes are still performing asymptomatic testing after vax of staff & residents even though symptomatic swabbing would reveal what we need to know but think this recent MMWR paper important
cdc.gov/mmwr/volumes/7…

in that 22 breakthroughs (most asymptomatic or mild due to good T cell immunity; older patients may not mount as good T cell immunity in some cases), careful contract tracing done and NO transmissions from these breakthrough within facility adding to our transmission table

But what is so important isn't it, is if your viral load is low in your nose as you fight a new infection and so can't transmit as shown in other studies, like CID nursing home study? (3 here)
nature.com/articles/s4159…
medrxiv.org/content/10.110…
academic.oup.com/cid/advance-ar…

The 2nd article above shows us viral loads decreased at least 4-fold when swab after vaccination and a large study from UK published this week likely even lower by CT values in millions of PCR tests done on asymptomatic individuals after vaccination
medrxiv.org/content/10.110…

This study shows us how important viral loads are in the nose when assessing risk of transmission (asymptomatic even prior to vax 4-fold less likely to transmit) so the very low viral loads in vax unlikely to transmit
thelancet.com/journals/lanin…

So consider this in your testing strategies at schools, nursing homes, workplaces as you open to test only symptomatic people after vaccination (and yes, send for sequencing per CDC surveillance)
popsci.com/story/health/t…

And consider this when you look at reports of breakthrough infections in the literature- first 1) look if asymptomatic (probably shouldn't have been tested); 2) mild (T cells doing their job); 3) severe (rare) - failure of immune response rarely to vax
salon.com/2021/04/17/bre…

Oh and in terms of breakthrough infections in U.S., rate remains astoundingly low. Out of 87 million fully vaccinated, only 5079 symptomatic breakthroughs (0.005%) & only 0.0003% hospitalizations related to COVID-19 & only 0.00009% deaths related to COVID.
cdc.gov/vaccines/covid…