Moderna’s final analysis of our Phase 3 COVE Study is out (median follow-up 5.3 months):
•Against COVID-19: 93.2%
•Against severe COVID-19: 98.2%
•Against death caused by COVID-19: 100%
Efficacy is broken down by 2-month segments post-second dose. A little after four months post-second dose efficacy is 92.4%.
Lab studies show 50µg boosters (which is half the dose of our original vaccine) increases antibody levels against Delta by 42-fold. We are working on a variant specific booster for Delta (mRNA-1273.617) as we did with Beta (mRNA-1273.351). Onto the topic of boosters this season.
With Delta, we are aware the possibility of breakthrough cases increases. DO remember initial neutralizing antibodies from the vaccines DO wane with time! One thing this presentation does not take into account is T-cells/cell-mediated immunity.
Remember, when initial vaccine induced antibodies wane, your immune system will kick in and make more when it needs to when you’re exposed to the virus. In addition, erosion of antibody neutralization (due to age, time since your dose, etc.) is likely to produce a larger drop in vaccine efficacy for an already-evasive variant more so than for a less evasive one- yes, we knew this too, hence the need for boosters this year for the elderly/most-at risk. I have stated this numerous times. Why is this? Because initial nAbs help prevent infection BUT is not a sole indicator of vaccine effectiveness (please keep that in mind). Lower levels of antibodies can still protect against the virus but for the most vulnerable who can’t fight an infection as easy as some of the rest of us, boosters are recommended as TCRs kick in after you’re exposed again.
Side note- a really good study on this point: biorxiv.org/content/10.110…
SARS-CoV-2-specific memory B-cells can persist in the elderly despite loss of neutralizing antibodies in case you fancy some more reading. Let’s continue.
SARS-CoV-2-specific memory B cells can persist in the elderly despite loss of neutralising antibodies.
It IS normal for initial antibody titers to drop over time. Yes, it happens! What matters is how quickly memory cells kick back in to mount a secondary response upon next exposure as I said above. For the vulnerable/elderly, this drop might happen faster and therefore that’s why a booster is heavily needed/suggested. Data is still being collected to make a full determination as to what booster is best.
Now, stop right there for a second. It has not been said EVERYONE WILL need them. You might be reading that in certain news outlets, and frankly I wouldn’t be surprised. If anything, it is mostly suggested that those who are considered to be high-risk to consider a booster for added protection (I have been saying this for months). AND IF someone wants one who isn’t considered high-risk, eventually they will be available but high-risk groups will be prioritized. Personally, I feel we should prioritize high-risk groups and countries with low vaccine supply immediately. You can find presentation data here:
https://investors.modernatx.com/static-files/c43de312-8273-4394-9a58-a7fc7d5ed098