One way our bodies prevent infection a second time by the same germ is to produce proteins called antibodies. The initial infection leads to antibody production that is specific to that infection. When the germ enters our body the next time, antibodies attack and neutralize it.
You’ve heard of vaccines. They work by inducing production of antibodies.
From South China Morning Post:
Researchers in Shanghai hope to determine whether some recovered coronavirus patients have a higher risk of reinfection after finding surprisingly low levels of Covid-19 antibodies in a number of people discharged from hospital.
A team from Fudan University analysed blood samples from 175 patients discharged from the Shanghai Public Health Clinical Centre and found that nearly a third had unexpectedly low levels of antibodies.
In some cases, antibodies could not be detected at all.
Source: Coronavirus: low antibody levels raise questions about reinfection risk | South China Morning Post
From National Geographic on April 10
If the past is any indicator, the world won’t have a coronavirus vaccine for more than a year, probably longer. The mumps vaccine—considered the fastest ever approved—took four years to go from collecting viral samples to licensing a drug in 1967. Clinical trials come with three phases, and the first stages of the current COVID-19 trials aren’t due for completion until this fall, spring 2021, or much later. And there are good reasons to allow time for safety checks. Some preliminary vaccines for the related coronavirus SARS, for instance, actually enhanced the disease in model experiments.
One major hitch in developing a COVID-19 vaccine is that no medically proven predecessor exists for any type of human coronavirus. This despite the fact that the 2002 SARS and 2012 MERS outbreaks, both caused by viral cousins of the new coronavirus, were warning shots that claimed about 1,600 lives.
Be skeptical about all the vaccine happytalk you hear from Trump, Birx, Fauci, et al.
Steve Parker, M.D.