When will it be safe to shop at a grocery store or show up at the office without wearing a mask? Sooner than most experts are willing to admit. If the coronavirus epidemic in the United States continues on its current trajectory, the need for masks outside specific local outbreak areas will pass in a matter of weeks.
One way to think about the problem is by analogy with seasonal flu. Almost no one wears a mask in normal environments to protect against the flu, and no one is obliged to do so. The worst flu seasons in recent years averaged 220 deaths a day across the country. Covid-19’s seven-day moving average for daily deaths hovers around 900, which is considerably worse. But it has been a 78% reduction since January, and trends are favorable in almost the entire country. When Covid’s 14-day moving average of daily deaths drops below the flu level, which can happen within a month or two, we must adjust our thinking about the coronavirus accordingly.
Vaccination is the main reason for the sharp decline in Covid’s cases and deaths. About three million injections are being administered each day and, once immunity has been activated, vaccinees are at insignificant risk of being infected, let alone spreading the infection. If you have been vaccinated, there is almost no direct safety benefit – for you or others – of wearing a mask. You still need to do this just because the immunity is invisible. The expectation or requirement to wear a mask is impracticable to be imposed only on those who are vulnerable or may be dangerous.
At some point, however, herd immunity is achieved: a sufficient number of the population is immune to make the risk of infection minimal in the population as a whole. Anthony Fauci sets the limit for herd immunity on the total vaccination of 85% of the US population, including children. Since the vaccine was only authorized for patients aged 16 and over and not all adults are willing to accept it, Dr. Fauci’s goal will almost certainly not be achieved for another year, if ever. The current figure is only 17% of the total population.
Dr. Fauci’s benchmark is too high. He ignores that many unvaccinated Americans – perhaps as many as 120 million, as seroprevalence studies suggest that the true incidence levels are three to 20 times the infections caught – have immunity due to the previous infection. A recent large-scale Danish study found that previous infection provides approximately 80% protection for patients under 65 and 47% protection for older people. This difference is the reason why it is important to prioritize the elderly for vaccination, as the American authorities have done. Due to this combination of factors, we are likely to exceed 50% of the combined immunity in the next two weeks.