US could reach herd immunity by summer through vaccinations alone, CNN analysis finds

The pace of Covid-19 vaccine administration in the US continues to improve, each day bringing the country closer to herd immunity — the point at which enough people are protected against a disease that it cannot spread.The pace of Covid-19 vaccine administration in the US continues to improve, each day bringing the country closer to herd immunity — the point at which enough people are protected against a disease that it cannot spread.