More mysteries of COVID-19

Both from the most excellent Bloomberg Prognosis newletter.

• From the current Moderna study on vaccination of very young children:

  The drugmaker said Wednesday that its shot appeared effective for kids aged 6 months to 5 years. The trial found it generated a strong immune response, without any serious safety concerns. You could practically hear parents everywhere breathing a sigh of relief.
  
  But don’t start celebrating just yet. Dive into the data and it gets a bit more complicated: The shot was only around 44% effective in stopping Covid cases in the 6-month to 2-year age range, and around 38% effective for 2- to 5-year-olds. None of the 7,000 children in the trial contracted a severe case of the disease, but it's hard to tell whether the shot was the reason, since no one in a placebo group caught a severe case either.

• From South Korea, which has a relatively unique COVID-19 policy:

  In just one day, Covid-19 cases jumped by more than 220,000 to a world-topping daily tally of 621,328.
  
  Normally such a case count would cause shock and panic. But not in South Korea, where government officials were breathing a sigh of relief. Their singular focus — the fatality rate — was still falling, dropping to 0.14%, one of the world’s lowest. That meant Korea’s virus-death rate was less than one-10th that of the U.S. and the U.K.
  
  Unlike other countries that have given up and stopped tracking the virus, Korea continues to test everyone, at a cost of $1.3 billion so far, which led to the astronomical case counts. But testing diligence, combined with a focus on vaccinations, is credited with keeping hospitalizations and deaths low.