When the number of individuals infected with coronavirus exceeds 450,000 worldwide and more than one billion are locked up in their homes, scientists are grappling with one of the pandemic’s most important issues: do patients who survive the disease become immune to the virus?
The response is a confident yes, with some notable unknowns. That is relevant for a couple of reasons.
For example, people who are believed to be resistant may venture out of their homes and help shore up the workforce before a vaccine is available. The increasing immunity in the population is also the way the outbreak ends: with fewer and fewer people infecting, the coronavirus will lose its toehold, and also the most vulnerable citizens will become more isolated from the threat.
Immunity will carry early care, too. Antibodies obtained from the bodies of those who have recovered can be used to support those who are dealing with the coronavirus disease, called Covid-19.
The Food and Drug Administration on Tuesday approved the use of plasma from recovered patients for the treatment of certain severe cases. A day earlier, Gov. Andrew M. Cuomo announced that New York will become the first state to start studying serum from people who have recovered from Covid-19 to treat others who are severely ill. “This is a trial for patients who are in critical condition, but the New York State Department of Health has been working on this with some of the best health care providers in New York and we think it is exciting.
The first line of protection for the body against an infectious virus is an antibody called immunoglobulin M, whose job is to remain vigilant in the body and to alert the rest of the immune system to intruders such as viruses and bacteria.
Days after infection, this antibody is transformed by the immune system into a second form called immunoglobulin G, exquisitely engineered to identify and neutralize a particular virus.
This can take as long as a week to refine; both the method and the efficacy of the final antibodies can vary. Some people are making strong antibodies neutralizing to an infection while others are staging a milder response.
The antibodies produced by certain viruses— polio or measles, for example — in response to infection provide immunity for a lifetime. Yet coronavirus antibodies that cause the common cold survive for only one to three years— and this may also be true of their new cousin.
Research in macaques infected with the new coronavirus indicated the monkeys develop neutralizing antibodies and avoid further infection once infected. But it’s unknown how long the monkeys will stay immune, or people infected with the virus.