In the midst of dire Covid warnings, one crucial fact has been largely ignored: Cases are down 77% in the past six weeks. If a drug reduced the number of cases by 77%, we would call it a miracle pill. Why is the number of cases falling much faster than experts predicted?
In large part because natural immunity to previous infection is much more common than can be measured by testing. Tests have only recorded 10% to 25% of infections, depending on when someone got the virus during the pandemic. By applying a time-weighted average of 1 in 6.5 to the cumulative 28 million confirmed cases, about 55% of Americans would have natural immunity.
Now add people who are being vaccinated. As of this week, 15% of Americans have received the vaccine, and the number is rising rapidly. Former Food and Drug Commissioner Scott Gottlieb estimates that 250 million doses will have been delivered to about 150 million people by the end of March.
There is reason to believe that the country is speeding to an extremely low level of infection. As more people are infected, most of whom have mild or no symptoms, there are fewer Americans who can become infected. On the current trajectory, I expect Covid to be largely gone by April, allowing Americans to resume normal lives.
Antibody studies almost certainly underestimate natural immunity. Antibody assays do not capture antigen-specific T cells that develop “memory” once activated by the virus. Survivors of the 1918 Spanish flu were found in 2008 – 90 years later – to have memory cells that were still capable of making neutralizing antibodies.