Under real world conditions, the Pfizer and Moderna Covid-19 vaccines provide highly effective protection, according to a new report from the US Centers for Disease Control and Prevention.
At full vaccination, the vaccines were 90% effective at preventing infections, including infections that had no symptoms. At least 14 days after first dose but before second dose, they were 80% protective, according to the agency’s Morbidity and Mortality Weekly Report published Monday. The CDC said it is the first of many planned Covid-19 vaccine effectiveness studies.
The study looked at how the vaccines protected nearly 4,000 health care workers and first responders. The volunteers in the study worked in eight locations around the country and had been observed from mid-December to mid-March.
The CDC tested volunteers routinely regardless of symptoms. The CDC also monitored the volunteers through text message, e-mail and direct medical reports. The volunteers also did a nasal swab once a week.