In the long-term care study, Moderna stimulated a stronger immune response in frail, older adults. Moderna uses three times the mRNA. It’s probably the reason there are more symptoms associated with Moderna in younger adults, Bowdish said — “it’s surplus to requirements,” because younger people have stronger immune systems. In older people, more is better. But Bowdish doesn’t want the take-away to be one is better than the other. Pfizer of Moderna, “they’re equally good.”

Some breakthrough infections in the fully vaccinated will require hospitalization, and, in rare cases, death, Dr. Tom Frieden, former director of the CDC tweeted. “That doesn’t change the reality that vaccination is the best way to protect ourselves from COVID.”

At Toronto General Hospital, “the calls that we’re getting for the previously well people suddenly with severe respiratory failure who might need ECMO (effectively, an artificial lung) are all unvaccinated,” said Dr. Niall Ferguson, head of critical care medicine at Toronto’s University Health Network.