Question:  I’m wondering if there is any research on the incidence of the new variants in children, particularly the new delta variant that everyone seems worried about?  I have a 4 year old who just started back at daycare, and it seems like the masking is pretty inconsistent.  Also, could you resend the link to the page where you have everything archived?

Answer: We are still learning about the Delta variant, and there’s a lot we still don’t know, including whether it is more dangerous for children.  What we do know with high certainty is: 1) Vaccines are still effective against the Delta variant, though their effectiveness is slightly reduced; and 2) the Delta variant is more transmissible than the Alpha variant.  Because the Delta variant is more transmissible, and because children <12 are still not eligible for vaccination, we would expect to see increased cases among children as the Delta variant gains ground.  It’s not clear whether we would see increased severity.  I support pushing for consistent masking in your child’s school!  Here’s a synthesis of what we currently know.  And for future reference, daily posts are archived here: CovidQandA.org

1. Vaccines remain effective. Pfizer and AstraZeneca vaccines both protect against the Delta variant, but their effectiveness is slightly reduced after full vaccination.  Effectiveness following only one dose is, however, greatly reduced. (see Q&A of 5/25)
2. Delta variant is on the rise. In the United States, the Alpha variant is the most widely circulating type, but the Delta variant is increasing. Earlier this week, Dr. Facui warned that we cannot let the Delta variant become the dominant strain in the US, urging Americans to get vaccinated.  Delta currently accounts for 6% of sequenced viruses in the US.  Meanwhile, in the UK, the Delta variant is the dominant strain.  In its most recent weekly report of June 11 (today!), Public Health England states that the Delta variant accounts for 96% of all sequenced and genotyped cases. 
3. Delta variant is more transmissible than Alpha. With Delta cases surpassing Alpha cases in the UK and secondary attack rates higher when comparing Delta with Alpha, the evidence is strong that Delta is more transmissible.  For the most recent reporting week, Public Health England found that secondary attack rates were 11.3% for Delta compared with 8% for Alpha.  As a reminder, Alpha variant is already ~50% more transmissible than the original SARS-CoV-2 line.  It’s looking like Delta is 40% more transmissible than Alpha! 
4. Delta variant may result in more serious disease outcomes. Data on this front are far from conclusive, but preliminary data from England and Scotland indicate that Delta results in increased hospitalizations.  Of course, India’s experience with the Delta variant adds to concern.
5. Natural immunity may be weaker in response to the Delta variant.  Data are also far from conclusive on this front, but it is possible that immunity derived from previous COVID infection may be reduced in the face of Delta.  

Table 1. Delta Variant Risk Assessment as of 10 June (from Public Health England)