With input from Dr Monica Vasudev

SARS-CoV-2 More Infectious Than SARS-CoV-1: N-terminal domain (NTD) is the pivotal difference between SARS-CoV-1 and -2. This part of the protein has not really been paid attention to before, but it appears that this is a crucial part for the stability of the protein, said Dr. Mahmoud Moradi, of the University of Arkansas. Researchers noted in simulations that SARS-CoV-1 and SARS-CoV-2 have different ways of changing their shape, and on different time scales. SARS-CoV-1 moves faster, and activates and deactivates, thus not giving it enough time to stick to the human cell as it is not as stable. SARS-CoV-2 is stable and ready to attack. SARS-CoV-2, in its active state, is much more stable than the active state of SARS-CoV-1, thus rendering it a better chance of binding to the human receptor.

The dynamics is much slower for SARS-CoV-2. While SARS-CoV-1 moves between the active and inactive state quite often, SARS-CoV-2 is slow in that sense, giving it a better chance of binding.  (Medscape) Pfizer COVID Vaccine Protects Against Asymptomatic Infection: Pfizer/BioNTech COVID-19 vaccine was found to prevent both symptomatic disease as well as asymptomatic infection in a real-world review of Israeli health records. A large case-control study with more than one million people noted that the estimated vaccine effectiveness for documented infection was 46% (95% CI 40-51%) at 14-20 days after one dose of vaccine, and 92% (95% CI 88-95%) at least 7 days after the second dose.

(Medpage Today)

Antibody Titers: Healthcare workers with previous COVID-19 infection, based on laboratory-confirmed serology testing, were reported to have higher antibody titer responses to a single dose of the mRNA COVID-19 vaccine compared to those not previously infected, reports a study published in JAMA. (JAMA)

Dr KK Aggarwal

President CMAAO, HCFI and Past National President IMA