20 Sept 2021 Episode 174 Pfizer for kids?

Mon, 09/20/2021 - 20:29

Dear colleagues,

I was working on two other episodes (on recurrent infections and waning immunity), when I heard about the preliminary results of the Pfizer trial in 5-11 years kids.  Therefore, I decided to critically put it into perspective  

Ep 174-1 A and B: Pfizer announced favorable results of it’s vaccine in 5-11 years old kids with 2 doses of only 10 µg (one third of the adult dose).  The study shows comparable mean antibody titers and comparable side effects to the older groups (who received the 30 µg dose). However:

  • The  study included only 2200 children
  • Efficacy against infection and disease is not reported
  • It is only a press release and almost “data-free”

Obviously, the public health decision whether to vaccinate these kids depends on how likely they are to become severely ill, alsoin view of the delta variant.

Ep 174-2: MMWR report on 14 US states March-July:

  • Hospitalization rate in children 8/100,000 versus 164/100,000 in adults
  • One in three hospitalized children needs intensive care.
  • Distribution amongst 572 cases (Table p. 1083):
    • 42 % in 12-17 years old
    • 19 % 0-2 months
    • 17 % 5-11 years
  • Underlying conditions: obesity, chronic lung disease and prematurity (for the youngest group)

Ep 174-3: A second MMWR on a larger number (> 3000 hospitalizations) report from Sept shows the following:

  • Absolute numbers of COVID-19–associated hospitalization rates among children and adolescents rose nearly five-fold during late June–mid-August 2021, coinciding with circulation of Delta variant.  
  • Nevertheless: the propor­tions of hospitalized children and adolescents with severe disease were similar before and during the period of Delta predominance. 

→ Hence more infections, but no indication of increased pathogenicity of Delta in children

  • In adolescents: hospitalization rates were 10 times higher among unvaccinated than among fully vaccinated adolescents
  • The figures 1 and 2 clearly show that the most vulnerable age groups are 0-4 years (with most in the newborns) and 12-17 years.  Hospitalization rates in 5-11 years is about 5 times lower than in younger or older children!
  • CDC is very formal in the advice for prevention: Preventive measures …. are critical, including vaccination, universal masking in schools, and masking by persons aged ≥2 years in other indoor public spaces and child care centers.  Clearly, this advice is oriented towards a US audience, with an average vaccination rate well below most Western European countries.  

Ep 174--4: Another MMWR over 1 year confirms the just mentioned age distribution of hospitalizations.  Moreover, it is emphasized that Emergency department visits and hospital admissions in a 2-week period in August 2021 were higher in states with lower population vaccination coverage and lower in states with higher vaccination coverage.

Provisional Conclusion:

  • Young children (5-11 years old) are at a lower risk for severe disease than very young children or adolescents
  • Young children follow the infection- and disease trends in the general population and hence, could be indirectly protected, provided adolescents and adults are massively vaccinated.  
  • Therefore, we need a full picture of efficacy and side effects after vaccination before deciding to include 5-11 years in routine vaccination schemes.  

Are my conclusions reasonable?

Best wishes