#Genome sequencing of the #SARSCoV2 isolates from both the episodes suggest distinctly different virus , confirming reinfection.
Since the individuals were #asymptomatic during both episodes, and identified on regular #surveillance suggest asymptomatic #reinfections could be an under-reported entity. 2/2
Sinxe #healthcare workers have much higher risk of exposure, regular #surveillance of healthcare workers could potentially uncover the real #incidence
A lot of discussion about B.1.640.2 reported from Southern France 🇫🇷 and a preprint on the variant medrxiv.org/content/10.110…
This 🧵is to summarize what we know. 👇
🔴14 changes including N501Y and E484K, & 9 deletions in Spike
🔵B.1.640 (now renamed B.1.640.1) had been in the @WHO watchlist for quite some time (Nov 2021)
🔵Index case seemingly was from Cameroon (doesn't mean it originated there)
🔴Many of the mutations are shared with VoCs
🟢Though predates omicron, sequences have not grown rapidly
🟢 Mutation specific qPCR assays can screen and differentiate from Delta and Omicron
🔴We don't know whether the increasing cases in South France 🇫🇷 are associated with the new variant
🔴Transmissibility or Virulence : What should really worry us ?
Since these two have been widely discussed, given #omicron is around. A short explainer 👇.
3 plots below - from ~2x of Rt value and 1/2 of hospitalization rates (less virulent) to basal value (~ Delta wave)
Rt is the effective reproductive no.
One could clearly see why 2x Rt would create a sharper and ⏫rate of hospitalizations.
For a less virulent and highly transmissible variant, assuming 1/2x hospitalization rate, this would still create a significant wave of hospitalizations.
A much detailed mathematical basis to this was discussed in the past by @AdamJKucharski
SARS-CoV-2 Variants and RT-PCR
Can RT-PCR Detect Omicron ?
A short thread on the topic. 👇
RT-PCR is a sensitive molecular method widely used for the detection of SARS-CoV-2 in biological samples. This is based on the principle that short pieces of DNA (aka primers) can specifically target DNA/RNA and amplify them using a polymerase protein
Typically COVID-19 RT-PCR kits use 2 or more sets of primers which target the virus nucleic acid at 2 or more genes/sites in the genome. This is to improve the specificity of the detection. Combinations between N, E, RdRP and S genes are typically used.
What do we know about the B.1.1.529 variant of SARS-CoV-2 with a very large number of mutations
An updated thread on emerging evidence.
B.1.1.529 is a newly designated variant of SARS-CoV-2 github.com/cov-lineages/p…
This would not have been possible without the exemplary work of researchers in Africa who have sequenced and deposited the genomes in public domain which forms the basis of this variant designation.
Real-world data on effectiveness of BBV152 / Covaxin whole inactivated #COVID19 vaccine against symptomatic infection
👥Healthcare Workers at @aiims_newdelhi
🗓 Coincided with the 2nd wave in #Delhi majorly driven by VoCs thelancet.com/journals/lanin…
Adjusted effectiveness of BBV152 against symptomatic COVID-19 after 2 doses adm at least
🔸️14d before testing was 50% (95% CI 33–62; p<0·0001).
🔸️28d before testing was 46% (95% CI 22–62)
🔸️after excluding previous COVID19 cases, 14d before testing was 47% (95% CI 29–61)
In summary
🔸️Vaccine effectiveness requires at least 2 doses and 14 days after 2nd dose
What this means for #PublicHealth
🔸️ Underscores the need for completing vaccine schedule of 2doses
🔸️ Continued non-pharmacological measures in the face of a wave of infections