#Moderna says its vaccine shows durable 93% efficacy through 6 months.
Final analysis (median follow-up 5.3 mo):
-Against COVID19: 93.2%
-Against severe COVID19: 98.2%
-Against death: 100%
(Note: All data prior delta) 1/
Further break down of #Moderna efficacy by 2-month segments post 2nd dose; at month 4+, efficacy is 92.4%
#Pfizer vax (by months 4-6) efficacy is 84% - though against severe disease maintains 97%. 2/
Yet it expects antibody levels will start to wane, and with #delta there will be an increase in #breakthrough infections in fully vaccinated; it sees need for #boosters 3/
#Moderna says lab studies show a booster with half the dose of its #covid19 vaccine increases antibody levels against #delta by 42-fold. 4
#Moderna reports top-line findings from phase 2 study of #booster shot, noting neutralizing antibody titers had waned significantly by 6 months; Safety profile of dose 3 was similar to that of dose 2. 5/
The @WHO yesterday called for a moratorium on #boosters until September to enable countries that haven't had vaccine access to be able to administer first shots. 6/
How well are the current #Covid vaccines performing?
In all fairness, we can say they are offering high protection against severe disease & deaths; considerable protection against the symptomatic disease; but only modest protection ag. infections/transmission of the disease 1/
To put it another way, the vaccines are contributing little to our fight against the frequent surges of the #SARSCoV2 virus.
This leads to one pertinent question:
What ought to be the prime objective of the vaccination particularly amid an intense pandemic? 2/
To resist the ongoing outbreak or avoid hospitalizations and deaths?
A four-fold reduction in the hospitalisation & death rates is not much use if we just allow infections to reach four-fold the previous peak. 3/
The duration of immunity in #SARSCoV2 infected people remains unclear. Recent studies have estimated that the correlate of 50% protection from re-infection was 20% of the mean convalescent #NAbs titre 2/
The sera collected from a cohort of 125 individuals with RT-PCR confirmed SARSCoV2 infections up to 386 days after symptom onset. In the subset of 65 sera collected from day 151 to 386 after symptom onset, all remained positive in PRNT50 3/
A recent #Chinese study shows that the viral loads in the #Delta infections were ~1000 times higher than those in the earlier 19A/19B strain infections on the day when viruses were firstly detected 1/
#Delta not only had a shorter incubation period but also has a shorter latent period. So, the time difference stayed the same but with much higher viral load. That's terrible & explains near-vertical waves 2/
Because it binds & replicates faster, #Delta creates a higher viral load which triggers symptoms in a host much faster 3/
Like all viruses, #SARSCoV2 will continue to evolve. But it has limited number of moves available. It seems it is near to its ‘end game’. There is just not a lot of space for the spike to continue to change in ways that allow it to evade Abs but still bind to its receptors 2/
#Substitutions that allow the virus to resist antibodies will probably also decrease its affinity for #hACE2. This is exactly what we have seen with #DeltaPlus 3/
Can #SARSCoV2#variants fully evade #vaccine induced protection? Or even natural protection?
The rapid emergence of too many different #variants shows that the virus is struggling to survive! That is why it’s changing so fast, probably, to prolong its stay in human bodies 1/
Though #vaccines may not be working perfectly against some #VOCs, but those fully vaccinated are protected against severe disease & death. No VOC can completely evade the vaccine induced protection, especially against severe disease & death! Why?.......... 2/
The #variants do not have changes in T-cell epitopes because when you are infected with a variant that evades an antibody, that variant can go to someone else and evade their antibody too. So it spreads through the population.... 3/
Do children produce different types of #antibodies(Abs) against #SARSCoV2 than adults? 1/
Yes, children mostly produced Abs aimed at #Spike protein, which the virus uses to enter cells. Adults generate similar Abs, but also develop Abs against the #Nucleocapsid protein, which is essential for viral replication 2/
#Nucleocapsid protein is typically released in significant quantities only when a virus is widespread in the body.
What does it mean? The kids lacked nucleocapsid-specific Abs, which suggests that they aren’t experiencing widespread infection. 3/