Luis Graca Profile picture
Jul 28, 2022 9 tweets 7 min read Read on X
Proud to present BA.5-infection risk drops after BA.1/BA.2 infection – data from the national Portuguese registry, one of the countries first hit with BA.5. Important, as adapted vaccines in development are BA.1-based. Follow the twitorial! 1/9 @lgraca medrxiv.org/content/10.110…
First, we used the SARS-CoV-2 genetic diversity surveillance data (great work from @irj_pt and J.P. Gomes) to define periods where each variant was dominant (>90% of national sample isolates). 2/9 #COVID19PT #DGS #INSA #InstitutoRicardoJorge Image
Next, we extracted from the Portuguese COVID-19 registry (SINAVE) all infections from periods of dominance by each variant. SINAVE is very comprehensive, and until recently, there was a large testing effort in the country. Kudos to @DGSaude for maintaining the registry. 3/9 Image
We were then in a position to calculate the risk for BA.5 infection (dominance after June 1st) in people initially infected in a period of dominance of Wuhan, Alpha, Delta, BA.1/BA.2, as well as individuals without a documented infection. 4/9 Image
It is almost a prospective study, but in the past: groups of people with infection with different variants (and without two or more infections) were selected. Then, we followed what happened to them during the period between June 1st - july 4th, all under similar conditions! 5/9
Compared with people without a documented infection, one past infection with any variant reduces the risk of BA.5 infection, especially for people infected with BA.1/BA.2 that have a risk about 5 times lower than the uninfected. 6/9 Image
Note that these are results from a highly vaccinated population: the Portuguese population aged 12 and older (in the study) had 98% coverage with the primary vaccination series by the end of 2021 (the total in the graph includes ages 0-11). 7/9
#CTVC #COVID19vaccines @DGSaude Image
What about unreported cases among the “uninfected”? We tested that. Assuming an additional 29.2% of unreported infections (data from the @irj_pt national serologic survey), results don’t change much. Even if unreported cases were 20% or 40%. (graph: assumes 29.2% unreported) 8/9 Image
This work was a collaboration with M Carmo Gomes, Ruy Ribeiro, @VlterRFonseca1, the team from DSIA of @DGSaude The last word goes for the PhD student that was dealing with the tables and scripts @jtmalato 9/9
@IMMolecular @medicina_lisboa @FC_UL

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More from @lgraca

Apr 8, 2023
Happy to share “The expanding family of Tfr cells”, a Focus on @SciImmunology (@lgraca, @saum_kmr & @jotraceyja24) about a @nromberg_ ’s paper. Follow this thread for a summary of Tfr diversity (and @nromberg_'s work). science.org/doi/10.1126/sc… @IMMolecular @medicina_lisboa
The first Tfr cells described, derived from Foxp3+ Treg cells, are the most abundant, autoreactive (TCR similar to Treg's), and they come in two flavors: CD25+, and the most mature CD25- (to escape IL-2 inhibition). Check this review from our group:
doi.org/10.1111/imr.12…
Circulating Tfr cells derive from Treg cells within lymphoid tissue and have an immature phenotype. The differentiation of circulating Tfr and tissue Tfr cells from Treg cells in humans was elucidated by @saum_kmr and @lgraca in detail:
science.org/doi/10.1126/sc…
Read 11 tweets
Jan 6, 2023
Happy to share our 1st publication of 2023! Hybrid immunity (protection against Omicron BA.5 infection acquired by vaccination + Omicron BA.1/BA.2 infection) is stable over 8 months. Data from the 🇵🇹registry.🧵1/12
thelancet.com/journals/lanin…
@IMMolecular @lgraca @TheLancetInfDis
We previously showed that BA.1/BA.2 infection in a highly vaccinated population (Portugal) provides substantial protection against subsequent omicron BA.5 infection: nejm.org/doi/full/10.10… Similar results reported in Denmark and Qatar. What about the waning of protection? 2/12
We now address stability of the added protection conferred by infection of a vaccinated person (hybrid immunity). Using SARS-CoV-2 genetic surveillance data (great work from @irj_pt and J.P. Gomes), we defined periods when BA.1/BA.2 and BA.5 were dominant (>90% of isolates).3/12 Image
Read 12 tweets

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