Question: My parents, who live in India, just tested positive for Covid.  They have had both doses of the AstraZeneca vaccine and are not experiencing any symptoms (maybe fatigue, but that could be unrelated).  Do we have any good data on AZ vaccine and severity of covid? I know things are muddy given this “double variant” but I am hopeful.

Answer: Please send your parents my best wishes.  Your hope is powerful and good!  And based on what we currently know, the AZ vaccine is indeed very likely to protect them against severe disease.   

First off, we don’t know what form of COVID your folks contracted– per a news updated published in Nature yesterday, India’s massive COVID surge puzzles scientists, B.1.1.7 appears to be the dominant strain in some states (like Pubjab) while the “double variant”, B.1.617, appears to be the dominant strain in others (like Maharashtra).  When it comes to B.1.1.7, we do have good data that AZ protects against severe outcomes.  Results from a randomized control trial published in Lancet three weeks ago showed that AZ’s efficacy against symptomatic infection was 70·4% (95% CI 43·6–84·5) for B.1.1.7 and 81·5% (67·9–89·4) for non-B.1.1.7 lineages.  Additionally, no participants from the study were hospitalised or died due to COVID. Though results point to lower efficacy, they still show a protective immune response.  Yes, more data are needed, but when it comes to AZ’s ability to prevent severe disease outcomes caused by the B.1.1.7 variant, the outlook is very promising.  [As a reminder, results from AZ’s phase 3 clinical trials in the UK, South Africa, and Brazil showed 100% efficacy against severe disease outcomes, including hospitalization and death.]      

Turning to the B.1.617 variant, you’re right that we don’t yet have good data on vaccine effectiveness.  Lab studies (e.g. in a culture dish) have shown that the viral mutations exhibited by B.1.617 are more likely to evade immune response, but it’s not clear how these findings translate into real life.  For example, scientists also found similar immune evasion results with the B.1.1.7 variant during lab studies, but in the real world (as discussed above) the immune response was still strong enough to prevent severe disease.  Back in the “real world”, Reuters reported earlier this week the statements of an Israeli health official, who described that based on seven cases of the B.1.617 variant recently identified, “the impression is that the Pfizer vaccine has efficacy against it, albeit a reduced efficacy.”  Clearly, this statement is not related to AZ directly and is an “impression” rather than fact.  Given how limited data on B.1.617 are right now, it is still promising to hear that vaccines seem to be working against the variant, even if the vaccines aren’t working as robustly.