How far are we from herd immunity?

The results of these recent serological surveys suggest that undetected infections are twice as high as diagnosed cases. Since some 30 million cases have been diagnosed, the serological surveys suggest that 90 million Americans have actually been infected with the virus so far. This infection rate is close to the 98 million estimate made by data scientist Youyang Gu in his path to normality projections.

So assuming herd immunity kicks in when 230 million Americans (70 percent) are either vaccinated or have been infected and recovered, how far are we from that goal? Let’s just do a very rough and optimistic calculation by assuming significant immunity among the 74 million Americans who have already gotten at least one dose of vaccine, plus the infection number of 90 million. That adds up to 164 million people who currently have antibodies against the virus, which is about 70 percent of the way toward the goal of 230 million people.

At the current rate of 2.5 million vaccinations per day, another 75 million Americans will be partially or fully vaccinated in the next month, bringing the total number of people with antibodies to 240 million by the middle of April.