Covid-19 vaccines remain highly effective against hospitalizations and death, even as the more contagious delta variant is spreading rapidly in the United States, according to studies released Friday.
A study tracked more than 600,000 COVID-19 cases in 13 states from April to mid-July. As the delta variant spread in early summer, those who weren’t vaccinated were 4.5 times more likely to become infected than those fully vaccinated, 10 times more likely to be hospitalized and 11 times more likely to die, according to the Centers for Disease Control. Disease Control and Prevention (CDC).
“Vaccination works,” CDC director Dr. Rochelle Walensky said at a briefing at the White House on Friday. “The bottom line is this: we have the scientific tools we need to turn this pandemic around.”
But as previous data have shown, protection is waning: It was 91% in the spring and 78% in June and July, the study found.
Cases of infections in fully vaccinated people accounted for 14% of hospitalizations and 16% of deaths in June and July, almost double than a few months ago.
This increase is not surprising: No one said vaccines were perfect, and health experts warned that as more Americans get vaccinated, they would account for a larger fraction of cases.
Walensky said on Friday that more than 90% of people hospitalized for COVID-19 in the country are not vaccinated.
The CDC released two other studies on Friday that indicate waning protection for older adults.
It is not clear if the changes observed over time are due to the fact that immunity is declining in people who were vaccinated for the first time many months ago, because the vaccine is not as effective against delta, or because much of the country has left. face masks and other precautions just as the most contagious variant was beginning to spread.
But health authorities will take this into account when deciding whether Americans need a booster shot and how soon after their last dose. Next week, advisers to the Food and Drug Administration (FDA) will publicly debate Pfizer’s request to offer a third dose.