Among many surprising developments during this pandemic, the most stunning has been the questioning of naturally acquired immunity after a person has had the Covid disease.
(Article by Martin Kulldorff republished from Brownstone.org)
We have understood natural immunity since at least the Athenian Plague in 430 BC. Here is Thucydides:
‘Yet it was with those who had recovered from the disease that the sick and the dying found most compassion. These knew what it was from experience and had no fear for themselves; for the same man was never attacked twice—never at least fatally.’ – Thucydides
We have lived with endemic coronaviruses for at least a hundred years, for which we have long-lasting natural immunity. As expected, we also have natural immunity after Covid-19 disease, as there have been exceedingly few reinfections with serious illness or death, despite a widely circulating virus.
For most viruses, natural immunity is better than vaccine-induced immunity, and that is also true for Covid. In the best study to date, the vaccinated were around 27 times more likely to have symptomatic disease than those with natural immunity, with an estimated range between 13 and 57. With no Covid deaths in either group, both natural and vaccine immunity protect well against death.
During the last decade, I have worked closely with hospital epidemiologists. While the role of physicians is to treat patients and make them well, the task of the hospital epidemiologist is to ensure that patients do not get sick while in the hospital, such as catching a deadly virus from another patient or a caretaker.
For that purpose, hospitals employ a variety of measures, from frequent hand washing to full infection control regalia when caring for an Ebola patient. Vaccinations are a key component of these control efforts. For example, two weeks before spleen surgery, patients are given the pneumococcal vaccine to minimize postoperative infections, and most clinical staff are immunized against influenza every year.
Infection control measures are especially critical for older frail hospital patients with a weakened immune system. They can become infected and die from a virus that most people would easily survive. A key rationale for immunizing nurses and physicians against influenza is to ensure that they do not infect such patients.
How can hospitals best protect their patients from Covid disease? It is an enormously important question, also relevant for nursing homes. There are some obvious standard solutions, such as separating Covid patients from other patients, minimizing staff rotation, and providing generous sick leave for staff with Covid-like symptoms.
Another goal should be to employ staff with the strongest possible immunity against Covid, as they are less likely to catch it and spread it to their patients. This means that hospitals and nursing homes should actively seek to hire staff that have natural immunity from prior Covid disease and use such staff for their most vulnerable patients.