For the record, I'm re-posting what my former school mate has to say about the COVID-19. It will give us a fairly good idea of what mainstream sources know (she is a virologist):
[google translation]
Can one become twice infected with SARS COV-2? Is Natural Immunity Protective?
Now the answer based on scientific evidence:
NOT KNOWN YET !!!
For the following reasons:
1. The possibility is discussed because there have been patients who, after being discharged, relapse, return to seek medical attention and test positive for SARS-VOC-2 again.
This virus or parts of the virus have a very long and somewhat erratic excretion.
* In a study by Zhou et al in Lancet (doi: 10.1016 / S0140-6736 (20) 30566-3) indicate that
patients can have positive results by Rt-PCR up to 20 days after the onset of symptoms or until the death.
-> So a positive RT-PCR after re-entry does not necessarily mean re-infection, but rather means
prolonged excretion.
2. Is the immunity produced protective? It is not yet known for this coronavirus.
* For other coronaviruses such as SARS1, it is believed that in 3 years a person can become reinfected (doi: 10.3201 / eid1310.070576).
* Very old studies from the 80s-90s where experiments were carried out with volunteers who were inoculated with the respiratory coronavirus 229E (doi: 10.1017 / s0950268800048019), all mounted an immune response and then after one year, they attempted to reinfect them. Many were reinfected, although producing a milder clinical picture. THIS TYPE OF STUDY MADE UNDERSTAND THAT RE-INFECTION WITH RESPIRATORY CORONAVIRUS AFTER A TIME IN WHICH THE IMMUNITY IS LOWERED IS POSSIBLE (and is observed year by year in the clinical setting).
* However, for other coronaviruses using animal models (doi: 10.3201 / 2206.160192, doi: 10.1371 / journal.ppat.1006565) the results are conflicting, sometimes protecting against reinfection and sometimes not.
* In a pre-print (a macaque model using SARS-COV2 (doi:
Reinfection could not occur in SARS-CoV-2 infected rhesus macaques) has not been published or peer reviewed yet) indicate that re -infection is not possible, but this was performed only 28 days after the first infection. These experiments should be done after at least 1 year to determine if immunity is protective.
-> THEREFORE, IT IS VERY SOON TO DETERMINE HOW THESE VIRUSES WILL BEHAVE IN THE HUMAN POPULATION WITH RESPECT TO WHETHER THE NATURAL IMMUNITY IS PROTECTIVE AGAINST RE-INFECTIONS OR NOT.
* and this must be taken into account when trying to produce a vaccine ...
[end of quote]