Your COVID-19 Questions & Answers
Response from Tom Belhorn
Q:
I read the WHO has warned that there is no evidence that COVID-19 infection causes immunity. I thought there was some immunity after SARS. Is the immune response different? Can I get COVID-19 again?
A:
The WHO desired to make a statement warning people that much is unknown about the immune response against COVID-19 after natural infection. There is no evidence that shows a lack of an immune response, but it is more a lack of evidence of how long and how protective the immune response will be after infection.
Endemic coronaviruses yield antibodies that last a period of a few years (though variable). Both SARS and MERS infection yielded neutralizing antibody. Most people infected with either virus were still antibody-positive after a year. The response to MERS seemed to wane quickly after that (antibody did not persist much longer than 12 months) but SARS antibody did persist for multiple years (at least a few years). It is important to remember that in natural infection the T cell immunity is also important and T memory cells persist. Decisions on vaccine development will need to take this into account. There is early promising data from COVID vaccine development and of course reports of efficacy of convalescent serum. So we have hope of some immunity- but we are not sure how long immunity will last.