Thread by @MonicaGandhi9

DO I NEED AN mRNA VACCINE BOOSTER AFTER A J&J SHOT? The answer to this is that no one knows, actually. Humility in COVID means we change our recommendations with changing data. And I also think there is no harm. But I don't see how the data indicates this yet.

Remember that J&J and mRNA vaccines actually not that different - J&J has DNA inside an adenovirus "vector" (that brings it in) and mRNA vaccines have mRNA inside a lipid envelope. The DNA from J&J gets "transcribed" into mRNA and that is the same mRNA in mRNA vax.

That mRNA is then "translated" into a part of the spike protein by your machinery and you see that spike protein, think it's different, and raise a vigorous immune response against it (antibodies; now we know memory B cells; memory T cells). Some vaccines need repeated boosters

to get strong response and some need 1 dose (like yellow fever vax). J&J vaccine interesting in that 1 dose in phase I/II trial showed increasing antibodies and T cell responses over time: kept on going up past 2 weeks out to 59 days when stopped looking
nejm.org/doi/full/10.10…

And I hope I & others already convinced you that T cell immunity against variants will be intact. This paper actually shows T cell responses of J&J worked just fine against alpha, beta, gamma (and CA) variant. And we discussed earlier that memory T cell
nature.com/articles/s4158…

responses from both natural infection & vaccine are very strong. In fact, memory T cell responses from natural infection with COVID resemble that of yellow fever vax in "half life" (rate of decay). Yellow fever vax usually given once over lifetime
science.sciencemag.org/content/early/…

And this paper shows 2 doses of mRNA vaccine raises quantity but not quality of T cells to COVID-19 (with natural infection needing only 1 dose of vaccine as many other studies have shown). So, what is answer? I don't know but do know that CDC has not
biorxiv.org/content/10.110…

reported increased breakthrough infections after J&J vaccine in their monitoring of breakthrough infections (and 12.5 million doses of J&J have been given out in US). And I know that J&J 1 dose trial was designed as 1 dose but 2 dose trial results coming.
covid.cdc.gov/covid-data-tra…

And I would also suggest to J&J that they give us some data on real world results as Pfizer has been very quick in their real-world effectiveness studies which inspires confidence. So, I don't think anyone knows but decreasing case rates across US (nytimes.com/interactive/20…) means

you are less likely to bump into COVID as a fully vaccinated person than you are in area with high community transmission rates (e.g. S. Africa right now for instance) so think you can wait for 2-dose trial. Again, see no harm but see no data yet for this strategy

Also think it's helpful to look at this whole delta variant thread in reference to this. A strain may be more "fit" and become the one that out-competes others but no evidence for more virulence or evading immunity

J&J data shows today (Dr. Fauci had hinted this would come out) that the vaccine produces a strong neutralizing antibody response to the delta variant. Good news for those concerned about needing another vax with J&J
wsj.com/articles/j-j-c…

And here is the J&J press release on this - strong and durable immune responses out to 8 months and counting. Strong activity against delta and all other variants. Two papers coming out soon & will describe.
jnj.com/positive-new-d…

Here is @NEJM paper on this. Looked at durability of immune responses with J&J vaccine out to 239 days Also looked at neutralizing Ab titers against alpha, beta, gamma, delta, epsilon. Strong antibody & cellular response with 1 dose out to 8 months
nejm.org/doi/full/10.10…

Here is the study yesterday that showed lower antibodies against delta variant in 10 people with J&J 1 shot vaccine (biorxiv.org/content/10.110…) & here is an interpretation of experts saying not as concerned due to T cells, other antibody studies
businessinsider.com/delta-variant-…

And here is some real-world data on the effectiveness in Mayo Clinic system. CDC has breakthrough data (on severe infection) on >4000 people who have received vax in US with 13 million J&J vax doses given, can stratify by vax type to see
medrxiv.org/content/10.110…

And here is some real world data from HCWs in S. Africa (Sisonke study). 94% of breakthrough infections are mild, 4% are moderate, 2% severe even with delta circulating. So, remember T cells vs Abs & how T cells protect from severe disease
samrc.ac.za/media-release/…