Diseases that we think of as “one-and-done” infections induce such a robust and durable immune response in a single encounter that we cannot be reinfected. In general terms, measles fits into this category, although there are rare reports of people contracting measles more than once.
The bad news is that viruses that infect via the mucus membranes of the nose and throat, like SARS-2, typically don’t induce sterilizing immunity.
“Sterilizing [immunity] in my view is out of the question, as with any respiratory virus,” said Marion Koopmans, head of virology at Erasmus Medical Center in Rotterdam, the Netherlands. Stanley Perlman, a Coronavirus researcher at the University of Iowa, called this option “not so likely.”
But Florian Krammer, a professor of vaccinology at the Icahn School of Medicine at Mount Sinai Hospital in New York, does believe some people will develop sterilizing immunity after a bout of Covid-19.
One last observation about sterilizing immunity: If infection doesn’t trigger it, there is reason to be concerned that
vaccines may not either. Peiris noted that so far most of the experimental vaccines, when tested in primates, protect the lungs from severe disease but don’t block replication of virus in the upper airways.
If the primates predict how the vaccines will work in people, these studies would suggest that people may still be able to be infected and they may emit viruses that potentially could infect others, but the type of Covid-19 disease that lands people in ICUs and that sometimes kills them would be prevented.
